# orm/mapper.py # Copyright (C) 2005, 2006, 2007 Michael Bayer mike_mp@zzzcomputing.com # # This module is part of SQLAlchemy and is released under # the MIT License: http://www.opensource.org/licenses/mit-license.php from sqlalchemy import sql, schema, util, exceptions, logging from sqlalchemy import sql_util as sqlutil from sqlalchemy.orm import util as mapperutil from sqlalchemy.orm import sync from sqlalchemy.orm.interfaces import MapperProperty, MapperOption, OperationContext, SynonymProperty import weakref, warnings __all__ = ['Mapper', 'MapperExtension', 'class_mapper', 'object_mapper', 'EXT_PASS', 'mapper_registry', 'ExtensionOption'] # a dictionary mapping classes to their primary mappers mapper_registry = weakref.WeakKeyDictionary() # a list of MapperExtensions that will be installed in all mappers by default global_extensions = [] # a constant returned by get_attr_by_column to indicate # this mapper is not handling an attribute for a particular # column NO_ATTRIBUTE = object() # returned by a MapperExtension method to indicate a "do nothing" response EXT_PASS = object() # lock used to synchronize the "mapper compile" step _COMPILE_MUTEX = util.threading.Lock() class Mapper(object): """Define the correlation of class attributes to database table columns. Instances of this class should be constructed via the ``sqlalchemy.orm.mapper()`` function. """ def __init__(self, class_, local_table, properties = None, primary_key = None, non_primary = False, inherits = None, inherit_condition = None, extension = None, order_by = False, allow_column_override = False, entity_name = None, always_refresh = False, version_id_col = None, polymorphic_on=None, _polymorphic_map=None, polymorphic_identity=None, concrete=False, select_table=None, allow_null_pks=False, batch=True, column_prefix=None): """Construct a new mapper. All arguments may be sent to the ``sqlalchemy.orm.mapper()`` function where they are passed through to here. class\_ The class to be mapped. local_table The table to which the class is mapped, or None if this mapper inherits from another mapper using concrete table inheritance. properties A dictionary mapping the string names of object attributes to ``MapperProperty`` instances, which define the persistence behavior of that attribute. Note that the columns in the mapped table are automatically converted into ``ColumnProperty`` instances based on the `key` property of each ``Column`` (although they can be overridden using this dictionary). primary_key A list of ``Column`` objects which define the *primary key* to be used against this mapper's selectable unit. This is normally simply the primary key of the `local_table`, but can be overridden here. non_primary Construct a ``Mapper`` that will define only the selection of instances, not their persistence. inherits Another ``Mapper`` for which this ``Mapper`` will have an inheritance relationship with. inherit_condition For joined table inheritance, a SQL expression (constructed ``ClauseElement``) which will define how the two tables are joined; defaults to a natural join between the two tables. extension A ``MapperExtension`` instance or list of ``MapperExtension`` instances which will be applied to all operations by this ``Mapper``. order_by A single ``Column`` or list of ``Columns`` for which selection operations should use as the default ordering for entities. Defaults to the OID/ROWID of the table if any, or the first primary key column of the table. allow_column_override If True, allows the usage of a ``relation()`` which has the same name as a column in the mapped table. The table column will no longer be mapped. entity_name A name to be associated with the `class`, to allow alternate mappings for a single class. always_refresh If True, all query operations for this mapped class will overwrite all data within object instances that already exist within the session, erasing any in-memory changes with whatever information was loaded from the database. version_id_col A ``Column`` which must have an integer type that will be used to keep a running *version id* of mapped entities in the database. this is used during save operations to ensure that no other thread or process has updated the instance during the lifetime of the entity, else a ``ConcurrentModificationError`` exception is thrown. polymorphic_on Used with mappers in an inheritance relationship, a ``Column`` which will identify the class/mapper combination to be used with a particular row. requires the polymorphic_identity value to be set for all mappers in the inheritance hierarchy. _polymorphic_map Used internally to propigate the full map of polymorphic identifiers to surrogate mappers. polymorphic_identity A value which will be stored in the Column denoted by polymorphic_on, corresponding to the *class identity* of this mapper. concrete If True, indicates this mapper should use concrete table inheritance with its parent mapper. select_table A ``Table`` or (more commonly) ``Selectable`` which will be used to select instances of this mapper's class. usually used to provide polymorphic loading among several classes in an inheritance hierarchy. allow_null_pks Indicates that composite primary keys where one or more (but not all) columns contain NULL is a valid primary key. Primary keys which contain NULL values usually indicate that a result row does not contain an entity and should be skipped. batch Indicates that save operations of multiple entities can be batched together for efficiency. setting to False indicates that an instance will be fully saved before saving the next instance, which includes inserting/updating all table rows corresponding to the entity as well as calling all ``MapperExtension`` methods corresponding to the save operation. column_prefix A string which will be prepended to the `key` name of all Columns when creating column-based properties from the given Table. Does not affect explicitly specified column-based properties """ if not issubclass(class_, object): raise exceptions.ArgumentError("Class '%s' is not a new-style class" % class_.__name__) for table in (local_table, select_table): if table is not None and isinstance(table, sql._SelectBaseMixin): # some db's, noteably postgres, dont want to select from a select # without an alias. also if we make our own alias internally, then # the configured properties on the mapper are not matched against the alias # we make, theres workarounds but it starts to get really crazy (its crazy enough # the SQL that gets generated) so just require an alias raise exceptions.ArgumentError("Mapping against a Select object requires that it has a name. Use an alias to give it a name, i.e. s = select(...).alias('myselect')") self.class_ = class_ self.entity_name = entity_name self.class_key = ClassKey(class_, entity_name) self.primary_key_argument = primary_key self.non_primary = non_primary self.order_by = order_by self.always_refresh = always_refresh self.version_id_col = version_id_col self.concrete = concrete self.single = False self.inherits = inherits self.select_table = select_table self.local_table = local_table self.inherit_condition = inherit_condition self.extension = extension self.properties = properties or {} self.allow_column_override = allow_column_override self.allow_null_pks = allow_null_pks self.delete_orphans = [] self.batch = batch self.column_prefix = column_prefix # a Column which is used during a select operation to retrieve the # "polymorphic identity" of the row, which indicates which Mapper should be used # to construct a new object instance from that row. self.polymorphic_on = polymorphic_on self._eager_loaders = util.Set() # our 'polymorphic identity', a string name that when located in a result set row # indicates this Mapper should be used to construct the object instance for that row. self.polymorphic_identity = polymorphic_identity # a dictionary of 'polymorphic identity' names, associating those names with # Mappers that will be used to construct object instances upon a select operation. if _polymorphic_map is None: self.polymorphic_map = {} else: self.polymorphic_map = _polymorphic_map class LOrderedProp(util.OrderedProperties): """this extends OrderedProperties to trigger a compile() before the members of the object are accessed.""" def _get_data(s): self.compile() return s.__dict__['_data'] _data = property(_get_data) self.columns = LOrderedProp() self.c = self.columns # each time the options() method is called, the resulting Mapper is # stored in this dictionary based on the given options for fast re-access self._options = {} # a set of all mappers which inherit from this one. self._inheriting_mappers = util.Set() # a second mapper that is used for selecting, if the "select_table" argument # was sent to this mapper. self.__surrogate_mapper = None # whether or not our compile() method has been called already. self.__is_compiled = False # if this mapper is to be a primary mapper (i.e. the non_primary flag is not set), # associate this Mapper with the given class_ and entity name. subsequent # calls to class_mapper() for the class_/entity name combination will return this # mapper. self._compile_class() self.__should_log_debug = logging.is_debug_enabled(self.logger) self.__log("constructed") # uncomment to compile at construction time (the old way) # this will break mapper setups that arent declared in the order # of dependency #self.compile() def __log(self, msg): self.logger.info("(" + self.class_.__name__ + "|" + (self.entity_name is not None and "/%s" % self.entity_name or "") + (self.local_table and self.local_table.name or str(self.local_table)) + (not self._is_primary_mapper() and "|non-primary" or "") + ") " + msg) def __log_debug(self, msg): self.logger.debug("(" + self.class_.__name__ + "|" + (self.entity_name is not None and "/%s" % self.entity_name or "") + (self.local_table and self.local_table.name or str(self.local_table)) + (not self._is_primary_mapper() and "|non-primary" or "") + ") " + msg) def _is_orphan(self, obj): optimistic = has_identity(obj) for (key,klass) in self.delete_orphans: if getattr(klass, key).hasparent(obj, optimistic=optimistic): return False else: if len(self.delete_orphans): if not has_identity(obj): raise exceptions.FlushError("instance %s is an unsaved, pending instance and is an orphan (is not attached to %s)" % ( obj, ", nor ".join(["any parent '%s' instance via that classes' '%s' attribute" % (klass.__name__, key) for (key,klass) in self.delete_orphans]) )) else: return True else: return False def _get_props(self): self.compile() return self.__props props = property(_get_props, doc="compiles this mapper if needed, and returns the " "dictionary of MapperProperty objects associated with this mapper." "(Deprecated; use get_property() and iterate_properties)") def get_property(self, key, resolve_synonyms=False, raiseerr=True): """return MapperProperty with the given key. forwards compatible with 0.4. """ self.compile() prop = self.__props.get(key, None) if resolve_synonyms: while isinstance(prop, SynonymProperty): prop = self.__props.get(prop.name, None) if prop is None and raiseerr: raise exceptions.InvalidRequestError("Mapper '%s' has no property '%s'" % (str(self), key)) return prop iterate_properties = property(lambda self: self._get_props().itervalues(), doc="returns an iterator of all MapperProperty objects." " Forwards compatible with 0.4") def compile(self): """Compile this mapper into its final internal format. This is the *external* version of the method which is not reentrant. """ if self.__is_compiled: return self _COMPILE_MUTEX.acquire() try: # double-check inside mutex if self.__is_compiled: return self self._compile_all() # if we're not primary, compile us if self.non_primary: self._do_compile() self._initialize_properties() return self finally: _COMPILE_MUTEX.release() def _compile_all(self): # compile all primary mappers for mapper in mapper_registry.values(): if not mapper.__is_compiled: mapper._do_compile() # initialize properties on all mappers for mapper in mapper_registry.values(): if not mapper.__props_init: mapper._initialize_properties() def _check_compile(self): if self.non_primary: self._do_compile() self._initialize_properties() return self def _do_compile(self): """Compile this mapper into its final internal format. This is the *internal* version of the method which is assumed to be called within compile() and is reentrant. """ if self.__is_compiled: return self self.__log("_do_compile() started") self.__is_compiled = True self.__props_init = False self._compile_extensions() self._compile_inheritance() self._compile_tables() self._compile_properties() self._compile_selectable() self.__log("_do_compile() complete") return self def _compile_extensions(self): """Go through the global_extensions list as well as the list of ``MapperExtensions`` specified for this ``Mapper`` and creates a linked list of those extensions. """ extlist = util.Set() for ext_class in global_extensions: if isinstance(ext_class, MapperExtension): extlist.add(ext_class) else: extlist.add(ext_class()) extension = self.extension if extension is not None: for ext_obj in util.to_list(extension): extlist.add(ext_obj) self.extension = _ExtensionCarrier() for ext in extlist: self.extension.append(ext) def _compile_inheritance(self): """Determine if this Mapper inherits from another mapper, and if so calculates the mapped_table for this Mapper taking the inherited mapper into account. For joined table inheritance, creates a ``SyncRule`` that will synchronize column values between the joined tables. also initializes polymorphic variables used in polymorphic loads. """ if self.inherits is not None: if isinstance(self.inherits, type): self.inherits = class_mapper(self.inherits, compile=False)._do_compile() else: self.inherits = self.inherits._do_compile() if not issubclass(self.class_, self.inherits.class_): raise exceptions.ArgumentError("Class '%s' does not inherit from '%s'" % (self.class_.__name__, self.inherits.class_.__name__)) if self._is_primary_mapper() != self.inherits._is_primary_mapper(): np = self._is_primary_mapper() and "primary" or "non-primary" raise exceptions.ArgumentError("Inheritance of %s mapper for class '%s' is only allowed from a %s mapper" % (np, self.class_.__name__, np)) # inherit_condition is optional. if self.local_table is None: self.local_table = self.inherits.local_table self.single = True if not self.local_table is self.inherits.local_table: if self.concrete: self._synchronizer= None self.mapped_table = self.local_table else: if self.inherit_condition is None: # figure out inherit condition from our table to the immediate table # of the inherited mapper, not its full table which could pull in other # stuff we dont want (allows test/inheritance.InheritTest4 to pass) self.inherit_condition = sql.join(self.inherits.local_table, self.local_table).onclause self.mapped_table = sql.join(self.inherits.mapped_table, self.local_table, self.inherit_condition) # generate sync rules. similarly to creating the on clause, specify a # stricter set of tables to create "sync rules" by,based on the immediate # inherited table, rather than all inherited tables self._synchronizer = sync.ClauseSynchronizer(self, self, sync.ONETOMANY) self._synchronizer.compile(self.mapped_table.onclause) else: self._synchronizer = None self.mapped_table = self.local_table if self.polymorphic_identity is not None: self.inherits._add_polymorphic_mapping(self.polymorphic_identity, self) if self.polymorphic_on is None and self.inherits.polymorphic_on is not None: self.polymorphic_on = self.mapped_table.corresponding_column(self.inherits.polymorphic_on, keys_ok=True, raiseerr=False) if self.order_by is False: self.order_by = self.inherits.order_by self.polymorphic_map = self.inherits.polymorphic_map self.batch = self.inherits.batch self.inherits._inheriting_mappers.add(self) else: self._synchronizer = None self.mapped_table = self.local_table if self.polymorphic_identity is not None: self._add_polymorphic_mapping(self.polymorphic_identity, self) if self.mapped_table is None: raise exceptions.ArgumentError("Mapper '%s' does not have a mapped_table specified. (Are you using the return value of table.create()? It no longer has a return value.)" % str(self)) # convert polymorphic class associations to mappers for key in self.polymorphic_map.keys(): if isinstance(self.polymorphic_map[key], type): self.polymorphic_map[key] = class_mapper(self.polymorphic_map[key]) def _add_polymorphic_mapping(self, key, class_or_mapper, entity_name=None): """Add a Mapper to our *polymorphic map*.""" if isinstance(class_or_mapper, type): class_or_mapper = class_mapper(class_or_mapper, entity_name=entity_name) self.polymorphic_map[key] = class_or_mapper def _compile_tables(self): """After the inheritance relationships have been reconciled, set up some more table-based instance variables and determine the *primary key* columns for all tables represented by this ``Mapper``. """ # summary of the various Selectable units: # mapped_table - the Selectable that represents a join of the underlying Tables to be saved (or just the Table) # local_table - the Selectable that was passed to this Mapper's constructor, if any # select_table - the Selectable that will be used during queries. if this is specified # as a constructor keyword argument, it takes precendence over mapped_table, otherwise its mapped_table # this is either select_table if it was given explicitly, or in the case of a mapper that inherits # its local_table # tables - a collection of underlying Table objects pulled from mapped_table if self.select_table is None: self.select_table = self.mapped_table # locate all tables contained within the "table" passed in, which # may be a join or other construct self.tables = sqlutil.TableFinder(self.mapped_table) # determine primary key columns, either passed in, or get them from our set of tables self.pks_by_table = {} if self.primary_key_argument is not None: # determine primary keys using user-given list of primary key columns as a guide # # TODO: this might not work very well for joined-table and/or polymorphic # inheritance mappers since local_table isnt taken into account nor is select_table # need to test custom primary key columns used with inheriting mappers for k in self.primary_key_argument: self.pks_by_table.setdefault(k.table, util.OrderedSet()).add(k) if k.table != self.mapped_table: # associate pk cols from subtables to the "main" table corr = self.mapped_table.corresponding_column(k, raiseerr=False) if corr is not None: self.pks_by_table.setdefault(self.mapped_table, util.OrderedSet()).add(corr) else: # no user-defined primary key columns - go through all of our represented tables # and assemble primary key columns for t in self.tables + [self.mapped_table]: try: l = self.pks_by_table[t] except KeyError: l = self.pks_by_table.setdefault(t, util.OrderedSet()) for k in t.primary_key: #if k.key not in t.c and k._label not in t.c: # this is a condition that was occurring when table reflection was doubling up primary keys # that were overridden in the Table constructor # raise exceptions.AssertionError("Column " + str(k) + " not located in the column set of table " + str(t)) l.add(k) if len(self.pks_by_table[self.mapped_table]) == 0: raise exceptions.ArgumentError("Could not assemble any primary key columns for mapped table '%s'" % (self.mapped_table.name)) self.primary_key = self.pks_by_table[self.mapped_table] def _compile_properties(self): """Inspect the properties dictionary sent to the Mapper's constructor as well as the mapped_table, and create ``MapperProperty`` objects corresponding to each mapped column and relation. Also grab ``MapperProperties`` from the inherited mapper, if any, and create copies of them to attach to this Mapper. """ # object attribute names mapped to MapperProperty objects self.__props = {} # table columns mapped to lists of MapperProperty objects # using a list allows a single column to be defined as # populating multiple object attributes self.columntoproperty = mapperutil.TranslatingDict(self.mapped_table) # load custom properties if self.properties is not None: for key, prop in self.properties.iteritems(): self._compile_property(key, prop, False) if self.inherits is not None: for key, prop in self.inherits.__props.iteritems(): if not self.__props.has_key(key): self._adapt_inherited_property(key, prop) # load properties from the main table object, # not overriding those set up in the 'properties' argument for column in self.mapped_table.columns: if self.columntoproperty.has_key(column): continue if not self.columns.has_key(column.key): self.columns[column.key] = self.select_table.corresponding_column(column, keys_ok=True, raiseerr=True) column_key = (self.column_prefix or '') + column.key prop = self.__props.get(column_key, None) if prop is None: prop = ColumnProperty(column) self.__props[column_key] = prop prop.set_parent(self) self.__log("adding ColumnProperty %s" % (column_key)) elif isinstance(prop, ColumnProperty): if prop.parent is not self: prop = ColumnProperty(deferred=prop.deferred, group=prop.group, *prop.columns) prop.set_parent(self) self.__props[column_key] = prop if column in self.primary_key and prop.columns[-1] in self.primary_key: warnings.warn(RuntimeWarning("On mapper %s, primary key column '%s' is being combined with distinct primary key column '%s' in attribute '%s'. Use explicit properties to give each column its own mapped attribute name." % (str(self), str(column), str(prop.columns[-1]), column_key))) prop.columns.append(column) self.__log("appending to existing ColumnProperty %s" % (column_key)) else: if not self.allow_column_override: raise exceptions.ArgumentError("WARNING: column '%s' not being added due to property '%s'. Specify 'allow_column_override=True' to mapper() to ignore this condition." % (column.key, repr(prop))) else: continue # its a ColumnProperty - match the ultimate table columns # back to the property proplist = self.columntoproperty.setdefault(column, []) proplist.append(prop) def _initialize_properties(self): """Call the ``init()`` method on all ``MapperProperties`` attached to this mapper. This happens after all mappers have completed compiling everything else up until this point, so that all dependencies are fully available. """ self.__log("_initialize_properties() started") l = [(key, prop) for key, prop in self.__props.iteritems()] for key, prop in l: if getattr(prop, 'key', None) is None: prop.init(key, self) self.__log("_initialize_properties() complete") self.__props_init = True def _compile_selectable(self): """If the 'select_table' keyword argument was specified, set up a second *surrogate mapper* that will be used for select operations. The columns of `select_table` should encompass all the columns of the `mapped_table` either directly or through proxying relationships. Currently, non-column properties are **not** copied. This implies that a polymorphic mapper can't do any eager loading right now. """ if self.select_table is not self.mapped_table: props = {} if self.properties is not None: for key, prop in self.properties.iteritems(): if sql.is_column(prop): props[key] = self.select_table.corresponding_column(prop) elif (isinstance(prop, list) and sql.is_column(prop[0])): props[key] = [self.select_table.corresponding_column(c) for c in prop] self.__surrogate_mapper = Mapper(self.class_, self.select_table, non_primary=True, properties=props, _polymorphic_map=self.polymorphic_map, polymorphic_on=self.select_table.corresponding_column(self.polymorphic_on), primary_key=self.primary_key_argument) def _compile_class(self): """If this mapper is to be a primary mapper (i.e. the non_primary flag is not set), associate this Mapper with the given class_ and entity name. Subsequent calls to ``class_mapper()`` for the class_/entity name combination will return this mapper. Also decorate the `__init__` method on the mapped class to include optional auto-session attachment logic. """ if self.non_primary: return if not self.non_primary and (mapper_registry.has_key(self.class_key)): raise exceptions.ArgumentError("Class '%s' already has a primary mapper defined with entity name '%s'. Use non_primary=True to create a non primary Mapper, or to create a new primary mapper, remove this mapper first via sqlalchemy.orm.clear_mapper(mapper), or preferably sqlalchemy.orm.clear_mappers() to clear all mappers." % (self.class_, self.entity_name)) attribute_manager.reset_class_managed(self.class_) oldinit = self.class_.__init__ def init(self, *args, **kwargs): entity_name = kwargs.pop('_sa_entity_name', None) mapper = mapper_registry.get(ClassKey(self.__class__, entity_name)) if mapper is not None: mapper = mapper.compile() # this gets the AttributeManager to do some pre-initialization, # in order to save on KeyErrors later on attribute_manager.init_attr(self) if kwargs.has_key('_sa_session'): session = kwargs.pop('_sa_session') else: # works for whatever mapper the class is associated with if mapper is not None: session = mapper.extension.get_session() if session is EXT_PASS: session = None else: session = None # if a session was found, either via _sa_session or via mapper extension, # and we have found a mapper, save() this instance to the session, and give it an associated entity_name. # otherwise, this instance will not have a session or mapper association until it is # save()d to some session. if session is not None and mapper is not None: self._entity_name = entity_name session._register_pending(self) if oldinit is not None: try: oldinit(self, *args, **kwargs) except: def go(): if session is not None: session.expunge(self) # convert expunge() exceptions to warnings util.warn_exception(go) raise # override oldinit, insuring that its not already a Mapper-decorated init method if oldinit is None or not hasattr(oldinit, '_sa_mapper_init'): init._sa_mapper_init = True try: init.__name__ = oldinit.__name__ init.__doc__ = oldinit.__doc__ except: # cant set __name__ in py 2.3 ! pass self.class_.__init__ = init _COMPILE_MUTEX.acquire() try: mapper_registry[self.class_key] = self finally: _COMPILE_MUTEX.release() if self.entity_name is None: self.class_.c = self.c def base_mapper(self): """Return the ultimate base mapper in an inheritance chain.""" if self.inherits is not None: return self.inherits.base_mapper() else: return self def common_parent(self, other): """Return true if the given mapper shares a common inherited parent as this mapper.""" return self.base_mapper() is other.base_mapper() def isa(self, other): """Return True if the given mapper inherits from this mapper.""" m = other while m is not self and m.inherits is not None: m = m.inherits return m is self def iterate_to_root(self): m = self while m is not None: yield m m = m.inherits def polymorphic_iterator(self): """Iterate through the collection including this mapper and all descendant mappers. This includes not just the immediately inheriting mappers but all their inheriting mappers as well. To iterate through an entire hierarchy, use ``mapper.base_mapper().polymorphic_iterator()``.""" yield self for mapper in self._inheriting_mappers: for m in mapper.polymorphic_iterator(): yield m def _get_inherited_column_equivalents(self): """Return a map of all *equivalent* columns, based on traversing the full set of inherit_conditions across all inheriting mappers and determining column pairs that are equated to one another. This is used when relating columns to those of a polymorphic selectable, as the selectable usually only contains one of two (or more) columns that are equated to one another. The resulting structure is a dictionary of columns mapped to lists of equivalent columns, i.e. { tablea.col1: [tableb.col1, tablec.col1], tablea.col2: [tabled.col2] } """ result = {} def visit_binary(binary): if binary.operator == '=': if binary.left in result: result[binary.left].append(binary.right) else: result[binary.left] = [binary.right] if binary.right in result: result[binary.right].append(binary.left) else: result[binary.right] = [binary.left] vis = mapperutil.BinaryVisitor(visit_binary) for mapper in self.base_mapper().polymorphic_iterator(): if mapper.inherit_condition is not None: vis.traverse(mapper.inherit_condition) return result def add_properties(self, dict_of_properties): """Add the given dictionary of properties to this mapper, using `add_property`. """ for key, value in dict_of_properties.iteritems(): self.add_property(key, value) def add_property(self, key, prop): """Add an indiviual MapperProperty to this mapper. If the mapper has not been compiled yet, just adds the property to the initial properties dictionary sent to the constructor. If this Mapper has already been compiled, then the given MapperProperty is compiled immediately. """ self.properties[key] = prop if self.__is_compiled: # if we're compiled, make sure all the other mappers are compiled too self._compile_all() self._compile_property(key, prop, init=True) def _create_prop_from_column(self, column): column = util.to_list(column) if not sql.is_column(column[0]): return None mapped_column = [] for c in column: mc = self.mapped_table.corresponding_column(c, raiseerr=False) if not mc: raise exceptions.ArgumentError("Column '%s' is not represented in mapper's table. Use the `column_property()` function to force this column to be mapped as a read-only attribute." % str(c)) mapped_column.append(mc) return ColumnProperty(*mapped_column) def _adapt_inherited_property(self, key, prop): if not self.concrete: self._compile_property(key, prop, init=False, setparent=False) # TODO: concrete properties dont adapt at all right now....will require copies of relations() etc. def _compile_property(self, key, prop, init=True, setparent=True): """Add a ``MapperProperty`` to this or another ``Mapper``, including configuration of the property. The properties' parent attribute will be set, and the property will also be copied amongst the mappers which inherit from this one. If the given `prop` is a ``Column`` or list of Columns, a ``ColumnProperty`` will be created. """ self.__log("_compile_property(%s, %s)" % (key, prop.__class__.__name__)) if not isinstance(prop, MapperProperty): col = self._create_prop_from_column(prop) if col is None: raise exceptions.ArgumentError("%s=%r is not an instance of MapperProperty or Column" % (key, prop)) prop = col self.__props[key] = prop if setparent: prop.set_parent(self) if isinstance(prop, ColumnProperty): # relate the mapper's "select table" to the given ColumnProperty col = self.select_table.corresponding_column(prop.columns[0], keys_ok=True, raiseerr=False) # col might not be present! the selectable given to the mapper need not include "deferred" # columns (included in zblog tests) if col is None: col = prop.columns[0] self.columns[key] = col for col in prop.columns: proplist = self.columntoproperty.setdefault(col, []) proplist.append(prop) if init: prop.init(key, self) for mapper in self._inheriting_mappers: mapper._adapt_inherited_property(key, prop) def __str__(self): return "Mapper|" + self.class_.__name__ + "|" + (self.entity_name is not None and "/%s" % self.entity_name or "") + (self.local_table and self.local_table.encodedname or str(self.local_table)) + (not self._is_primary_mapper() and "|non-primary" or "") def _is_primary_mapper(self): """Return True if this mapper is the primary mapper for its class key (class + entity_name).""" return mapper_registry.get(self.class_key, None) is self def primary_mapper(self): """Return the primary mapper corresponding to this mapper's class key (class + entity_name).""" return mapper_registry[self.class_key] def is_assigned(self, instance): """Return True if this mapper handles the given instance. This is dependent not only on class assignment but the optional `entity_name` parameter as well. """ return instance.__class__ is self.class_ and getattr(instance, '_entity_name', None) == self.entity_name def _assign_entity_name(self, instance): """Assign this Mapper's entity name to the given instance. Subsequent Mapper lookups for this instance will return the primary mapper corresponding to this Mapper's class and entity name. """ instance._entity_name = self.entity_name def get_session(self): """Return the contextual session provided by the mapper extension chain, if any. Raise ``InvalidRequestError`` if a session cannot be retrieved from the extension chain. """ self.compile() s = self.extension.get_session() if s is EXT_PASS: raise exceptions.InvalidRequestError("No contextual Session is established. Use a MapperExtension that implements get_session or use 'import sqlalchemy.mods.threadlocal' to establish a default thread-local contextual session.") return s def has_eager(self): """Return True if one of the properties attached to this Mapper is eager loading. """ return len(self._eager_loaders) > 0 def instances(self, cursor, session, *mappers, **kwargs): """Return a list of mapped instances corresponding to the rows in a given ResultProxy. """ import sqlalchemy.orm.query return sqlalchemy.orm.Query(self, session).instances(cursor, *mappers, **kwargs) def identity_key_from_row(self, row): """Return an identity-map key for use in storing/retrieving an item from the identity map. row A ``sqlalchemy.engine.base.RowProxy`` instance or a dictionary corresponding result-set ``ColumnElement`` instances to their values within a row. """ return (self.class_, tuple([row[column] for column in self.pks_by_table[self.mapped_table]]), self.entity_name) def identity_key_from_primary_key(self, primary_key): """Return an identity-map key for use in storing/retrieving an item from an identity map. primary_key A list of values indicating the identifier. """ return (self.class_, tuple(util.to_list(primary_key)), self.entity_name) def identity_key_from_instance(self, instance): """Return the identity key for the given instance, based on its primary key attributes. This value is typically also found on the instance itself under the attribute name `_instance_key`. """ return self.identity_key_from_primary_key(self.primary_key_from_instance(instance)) def primary_key_from_instance(self, instance): """Return the list of primary key values for the given instance. """ return [self.get_attr_by_column(instance, column) for column in self.pks_by_table[self.mapped_table]] def canload(self, instance): """return true if this mapper is capable of loading the given instance""" if self.polymorphic_on is not None: return isinstance(instance, self.class_) else: return instance.__class__ is self.class_ def instance_key(self, instance): """Deprecated. A synonym for `identity_key_from_instance`.""" return self.identity_key_from_instance(instance) def identity_key(self, primary_key): """Deprecated. A synonym for `identity_key_from_primary_key`.""" return self.identity_key_from_primary_key(primary_key) def identity(self, instance): """Deprecated. A synoynm for `primary_key_from_instance`.""" return self.primary_key_from_instance(instance) def _getpropbycolumn(self, column, raiseerror=True): try: prop = self.columntoproperty[column] except KeyError: try: prop = self.__props[column.key] if not raiseerror: return None raise exceptions.InvalidRequestError("Column '%s.%s' is not available, due to conflicting property '%s':%s" % (column.table.name, column.name, column.key, repr(prop))) except KeyError: if not raiseerror: return None raise exceptions.InvalidRequestError("No column %s.%s is configured on mapper %s..." % (column.table.name, column.name, str(self))) return prop[0] def get_attr_by_column(self, obj, column, raiseerror=True): """Return an instance attribute using a Column as the key.""" prop = self._getpropbycolumn(column, raiseerror) if prop is None: return NO_ATTRIBUTE #print "get column attribute '%s' from instance %s" % (column.key, mapperutil.instance_str(obj)) return prop.getattr(obj) def set_attr_by_column(self, obj, column, value): """Set the value of an instance attribute using a Column as the key.""" self.columntoproperty[column][0].setattr(obj, value) def save_obj(self, objects, uowtransaction, postupdate=False, post_update_cols=None, single=False): """Issue ``INSERT`` and/or ``UPDATE`` statements for a list of objects. This is called within the context of a UOWTransaction during a flush operation. `save_obj` issues SQL statements not just for instances mapped directly by this mapper, but for instances mapped by all inheriting mappers as well. This is to maintain proper insert ordering among a polymorphic chain of instances. Therefore save_obj is typically called only on a *base mapper*, or a mapper which does not inherit from any other mapper. """ if self.__should_log_debug: self.__log_debug("save_obj() start, " + (single and "non-batched" or "batched")) # if batch=false, call save_obj separately for each object if not single and not self.batch: for obj in objects: self.save_obj([obj], uowtransaction, postupdate=postupdate, post_update_cols=post_update_cols, single=True) return connection = uowtransaction.transaction.connection(self) if not postupdate: for obj in objects: if not has_identity(obj): for mapper in object_mapper(obj).iterate_to_root(): mapper.extension.before_insert(mapper, connection, obj) else: for mapper in object_mapper(obj).iterate_to_root(): mapper.extension.before_update(mapper, connection, obj) for obj in objects: # detect if we have a "pending" instance (i.e. has no instance_key attached to it), # and another instance with the same identity key already exists as persistent. convert to an # UPDATE if so. mapper = object_mapper(obj) instance_key = mapper.instance_key(obj) is_row_switch = not postupdate and not has_identity(obj) and instance_key in uowtransaction.uow.identity_map if is_row_switch: existing = uowtransaction.uow.identity_map[instance_key] if not uowtransaction.is_deleted(existing): raise exceptions.FlushError("New instance %s with identity key %s conflicts with persistent instance %s" % (mapperutil.instance_str(obj), str(instance_key), mapperutil.instance_str(existing))) if self.__should_log_debug: self.__log_debug("detected row switch for identity %s. will update %s, remove %s from transaction" % (instance_key, mapperutil.instance_str(obj), mapperutil.instance_str(existing))) uowtransaction.unregister_object(existing) if has_identity(obj): if obj._instance_key != instance_key: raise exceptions.FlushError("Can't change the identity of instance %s in session (existing identity: %s; new identity: %s)" % (mapperutil.instance_str(obj), obj._instance_key, instance_key)) inserted_objects = util.Set() updated_objects = util.Set() table_to_mapper = {} for mapper in self.base_mapper().polymorphic_iterator(): for t in mapper.tables: table_to_mapper.setdefault(t, mapper) for table in sqlutil.TableCollection(list(table_to_mapper.keys())).sort(reverse=False): # two lists to store parameters for each table/object pair located insert = [] update = [] for obj in objects: mapper = object_mapper(obj) if table not in mapper.tables or not mapper._has_pks(table): continue instance_key = mapper.instance_key(obj) if self.__should_log_debug: self.__log_debug("save_obj() table '%s' instance %s identity %s" % (table.name, mapperutil.instance_str(obj), str(instance_key))) isinsert = not instance_key in uowtransaction.uow.identity_map and not postupdate and not has_identity(obj) params = {} hasdata = False for col in table.columns: if col is mapper.version_id_col: if not isinsert: params[col._label] = mapper.get_attr_by_column(obj, col) params[col.key] = params[col._label] + 1 else: params[col.key] = 1 elif col in mapper.pks_by_table[table]: # column is a primary key ? if not isinsert: # doing an UPDATE? put primary key values as "WHERE" parameters # matching the bindparam we are creating below, i.e. "_" params[col._label] = mapper.get_attr_by_column(obj, col) else: # doing an INSERT, primary key col ? # if the primary key values are not populated, # leave them out of the INSERT altogether, since PostGres doesn't want # them to be present for SERIAL to take effect. A SQLEngine that uses # explicit sequences will put them back in if they are needed value = mapper.get_attr_by_column(obj, col) if value is not None: params[col.key] = value elif mapper.polymorphic_on is not None and mapper.polymorphic_on.shares_lineage(col): if isinsert: if self.__should_log_debug: self.__log_debug("Using polymorphic identity '%s' for insert column '%s'" % (mapper.polymorphic_identity, col.key)) value = mapper.polymorphic_identity if col.default is None or value is not None: params[col.key] = value else: # column is not a primary key ? if not isinsert: # doing an UPDATE ? get the history for the attribute, with "passive" # so as not to trigger any deferred loads. if there is a new # value, add it to the bind parameters if post_update_cols is not None and col not in post_update_cols: continue elif is_row_switch: params[col.key] = self.get_attr_by_column(obj, col) hasdata = True continue prop = mapper._getpropbycolumn(col, False) if prop is None: continue history = prop.get_history(obj, passive=True) if history: a = history.added_items() if len(a): params[col.key] = a[0] hasdata = True else: # doing an INSERT, non primary key col ? # add the attribute's value to the # bind parameters, unless its None and the column has a # default. if its None and theres no default, we still might # not want to put it in the col list but SQLIte doesnt seem to like that # if theres no columns at all value = mapper.get_attr_by_column(obj, col, False) if value is NO_ATTRIBUTE: continue if col.default is None or value is not None: params[col.key] = value if not isinsert: if hasdata: # if none of the attributes changed, dont even # add the row to be updated. update.append((obj, params, mapper)) else: insert.append((obj, params, mapper)) if len(update): mapper = table_to_mapper[table] clause = sql.and_() for col in mapper.pks_by_table[table]: clause.clauses.append(col == sql.bindparam(col._label, type=col.type, unique=True)) if mapper.version_id_col is not None: clause.clauses.append(mapper.version_id_col == sql.bindparam(mapper.version_id_col._label, type=col.type, unique=True)) statement = table.update(clause) rows = 0 supports_sane_rowcount = True def comparator(a, b): for col in mapper.pks_by_table[table]: x = cmp(a[1][col._label],b[1][col._label]) if x != 0: return x return 0 update.sort(comparator) for rec in update: (obj, params, mapper) = rec c = connection.execute(statement, params) mapper._postfetch(connection, table, obj, c, c.last_updated_params()) updated_objects.add(obj) rows += c.rowcount if c.supports_sane_rowcount() and rows != len(update): raise exceptions.ConcurrentModificationError("Updated rowcount %d does not match number of objects updated %d" % (rows, len(update))) if len(insert): statement = table.insert() def comparator(a, b): return cmp(a[0]._sa_insert_order, b[0]._sa_insert_order) insert.sort(comparator) for rec in insert: (obj, params, mapper) = rec c = connection.execute(statement, params) primary_key = c.last_inserted_ids() if primary_key is not None: i = 0 for col in mapper.pks_by_table[table]: if mapper.get_attr_by_column(obj, col) is None and len(primary_key) > i: mapper.set_attr_by_column(obj, col, primary_key[i]) i+=1 mapper._postfetch(connection, table, obj, c, c.last_inserted_params()) # synchronize newly inserted ids from one table to the next # TODO: this fires off more than needed, try to organize syncrules # per table def sync(mapper): inherit = mapper.inherits if inherit is not None: sync(inherit) if mapper._synchronizer is not None: mapper._synchronizer.execute(obj, obj) sync(mapper) inserted_objects.add(obj) if not postupdate: for obj in inserted_objects: for mapper in object_mapper(obj).iterate_to_root(): mapper.extension.after_insert(mapper, connection, obj) for obj in updated_objects: for mapper in object_mapper(obj).iterate_to_root(): mapper.extension.after_update(mapper, connection, obj) def _postfetch(self, connection, table, obj, resultproxy, params): """After an ``INSERT`` or ``UPDATE``, ask the returned result if ``PassiveDefaults`` fired off on the database side which need to be post-fetched, **or** if pre-exec defaults like ``ColumnDefaults`` were fired off and should be populated into the instance. this is only for non-primary key columns. """ if resultproxy.lastrow_has_defaults(): clause = sql.and_() for p in self.pks_by_table[table]: clause.clauses.append(p == self.get_attr_by_column(obj, p)) row = connection.execute(table.select(clause), None).fetchone() for c in table.c: if self.get_attr_by_column(obj, c, False) is None: self.set_attr_by_column(obj, c, row[c]) else: for c in table.c: if c.primary_key or not c.key in params: continue v = self.get_attr_by_column(obj, c, False) if v is NO_ATTRIBUTE: continue elif v != params.get_original(c.key): self.set_attr_by_column(obj, c, params.get_original(c.key)) def delete_obj(self, objects, uowtransaction): """Issue ``DELETE`` statements for a list of objects. This is called within the context of a UOWTransaction during a flush operation. """ if self.__should_log_debug: self.__log_debug("delete_obj() start") connection = uowtransaction.transaction.connection(self) for obj in objects: for mapper in object_mapper(obj).iterate_to_root(): mapper.extension.before_delete(mapper, connection, obj) deleted_objects = util.Set() table_to_mapper = {} for mapper in self.base_mapper().polymorphic_iterator(): for t in mapper.tables: table_to_mapper.setdefault(t, mapper) for table in sqlutil.TableCollection(list(table_to_mapper.keys())).sort(reverse=True): delete = [] for obj in objects: mapper = object_mapper(obj) if table not in mapper.tables or not mapper._has_pks(table): continue params = {} if not hasattr(obj, '_instance_key'): continue else: delete.append(params) for col in mapper.pks_by_table[table]: params[col.key] = mapper.get_attr_by_column(obj, col) if mapper.version_id_col is not None: params[mapper.version_id_col.key] = mapper.get_attr_by_column(obj, mapper.version_id_col) deleted_objects.add(obj) if len(delete): mapper = table_to_mapper[table] def comparator(a, b): for col in mapper.pks_by_table[table]: x = cmp(a[col.key],b[col.key]) if x != 0: return x return 0 delete.sort(comparator) clause = sql.and_() for col in mapper.pks_by_table[table]: clause.clauses.append(col == sql.bindparam(col.key, type=col.type, unique=True)) if mapper.version_id_col is not None: clause.clauses.append(mapper.version_id_col == sql.bindparam(mapper.version_id_col.key, type=mapper.version_id_col.type, unique=True)) statement = table.delete(clause) c = connection.execute(statement, delete) if c.supports_sane_rowcount() and c.rowcount != len(delete): raise exceptions.ConcurrentModificationError("Updated rowcount %d does not match number of objects updated %d" % (c.rowcount, len(delete))) for obj in deleted_objects: for mapper in object_mapper(obj).iterate_to_root(): mapper.extension.after_delete(mapper, connection, obj) def _has_pks(self, table): try: for k in self.pks_by_table[table]: if not self.columntoproperty.has_key(k): return False else: return True except KeyError: return False def register_dependencies(self, uowcommit, *args, **kwargs): """Register ``DependencyProcessor`` instances with a ``unitofwork.UOWTransaction``. This call `register_dependencies` on all attached ``MapperProperty`` instances. """ for prop in self.__props.values(): prop.register_dependencies(uowcommit, *args, **kwargs) def cascade_iterator(self, type, object, recursive=None, halt_on=None): """Iterate each element in an object graph, for all relations taht meet the given cascade rule. type The name of the cascade rule (i.e. save-update, delete, etc.) object The lead object instance. child items will be processed per the relations defined for this object's mapper. recursive Used by the function for internal context during recursive calls, leave as None. """ if recursive is None: recursive=util.Set() for prop in self.__props.values(): for c in prop.cascade_iterator(type, object, recursive, halt_on=halt_on): yield c def cascade_callable(self, type, object, callable_, recursive=None, halt_on=None): """Execute a callable for each element in an object graph, for all relations that meet the given cascade rule. type The name of the cascade rule (i.e. save-update, delete, etc.) object The lead object instance. child items will be processed per the relations defined for this object's mapper. callable\_ The callable function. recursive Used by the function for internal context during recursive calls, leave as None. """ if recursive is None: recursive=util.Set() for prop in self.__props.values(): prop.cascade_callable(type, object, callable_, recursive, halt_on=halt_on) def get_select_mapper(self): """Return the mapper used for issuing selects. This mapper is the same mapper as `self` unless the select_table argument was specified for this mapper. """ return self.__surrogate_mapper or self def _instance(self, context, row, result = None, skip_polymorphic=False): """Pull an object instance from the given row and append it to the given result list. If the instance already exists in the given identity map, its not added. In either case, execute all the property loaders on the instance to also process extra information in the row. """ # apply ExtensionOptions applied to the Query to this mapper, # but only if our mapper matches. # TODO: what if our mapper inherits from the mapper (i.e. as in a polymorphic load?) if context.mapper is self: extension = context.extension else: extension = self.extension ret = extension.translate_row(self, context, row) if ret is not EXT_PASS: row = ret if not skip_polymorphic and self.polymorphic_on is not None: discriminator = row[self.polymorphic_on] if discriminator is not None: mapper = self.polymorphic_map[discriminator] if mapper is not self: row = self.translate_row(mapper, row) return mapper._instance(context, row, result=result, skip_polymorphic=True) # look in main identity map. if its there, we dont do anything to it, # including modifying any of its related items lists, as its already # been exposed to being modified by the application. populate_existing = context.populate_existing or self.always_refresh identitykey = self.identity_key_from_row(row) if context.session.has_key(identitykey): instance = context.session._get(identitykey) if self.__should_log_debug: self.__log_debug("_instance(): using existing instance %s identity %s" % (mapperutil.instance_str(instance), str(identitykey))) isnew = False if context.version_check and self.version_id_col is not None and self.get_attr_by_column(instance, self.version_id_col) != row[self.version_id_col]: raise exceptions.ConcurrentModificationError("Instance '%s' version of %s does not match %s" % (instance, self.get_attr_by_column(instance, self.version_id_col), row[self.version_id_col])) if populate_existing or context.session.is_expired(instance, unexpire=True): if not context.identity_map.has_key(identitykey): context.identity_map[identitykey] = instance isnew = True if extension.populate_instance(self, context, row, instance, identitykey, isnew) is EXT_PASS: self.populate_instance(context, instance, row, identitykey, isnew) if extension.append_result(self, context, row, instance, identitykey, result, isnew) is EXT_PASS: if result is not None: result.append(instance) return instance else: if self.__should_log_debug: self.__log_debug("_instance(): identity key %s not in session" % str(identitykey) + repr([mapperutil.instance_str(x) for x in context.session])) # look in result-local identitymap for it. exists = context.identity_map.has_key(identitykey) if not exists: if self.allow_null_pks: # check if *all* primary key cols in the result are None - this indicates # an instance of the object is not present in the row. for col in self.pks_by_table[self.mapped_table]: if row[col] is not None: break else: return None else: # otherwise, check if *any* primary key cols in the result are None - this indicates # an instance of the object is not present in the row. for col in self.pks_by_table[self.mapped_table]: if row[col] is None: return None # plugin point instance = extension.create_instance(self, context, row, self.class_) if instance is EXT_PASS: instance = self._create_instance(context.session) else: instance._entity_name = self.entity_name if self.__should_log_debug: self.__log_debug("_instance(): created new instance %s identity %s" % (mapperutil.instance_str(instance), str(identitykey))) context.identity_map[identitykey] = instance isnew = True else: instance = context.identity_map[identitykey] isnew = False # call further mapper properties on the row, to pull further # instances from the row and possibly populate this item. if extension.populate_instance(self, context, row, instance, identitykey, isnew) is EXT_PASS: self.populate_instance(context, instance, row, identitykey, isnew) if extension.append_result(self, context, row, instance, identitykey, result, isnew) is EXT_PASS: if result is not None: result.append(instance) return instance def _create_instance(self, session): obj = self.class_.__new__(self.class_) obj._entity_name = self.entity_name # this gets the AttributeManager to do some pre-initialization, # in order to save on KeyErrors later on attribute_manager.init_attr(obj) return obj def translate_row(self, tomapper, row): """Translate the column keys of a row into a new or proxied row that can be understood by another mapper. This can be used in conjunction with populate_instance to populate an instance using an alternate mapper. """ newrow = util.DictDecorator(row) for c in tomapper.mapped_table.c: c2 = self.mapped_table.corresponding_column(c, keys_ok=True, raiseerr=True) if row.has_key(c2): newrow[c] = row[c2] return newrow def populate_instance(self, selectcontext, instance, row, identitykey, isnew): """populate an instance from a result row. This method iterates through the list of MapperProperty objects attached to this Mapper and calls each properties execute() method.""" for prop in self.__props.values(): prop.execute(selectcontext, instance, row, identitykey, isnew) Mapper.logger = logging.class_logger(Mapper) class MapperExtension(object): """Base implementation for an object that provides overriding behavior to various Mapper functions. For each method in MapperExtension, a result of EXT_PASS indicates the functionality is not overridden. """ def get_session(self): """Retrieve a contextual Session instance with which to register a new object. Note: this is not called if a session is provided with the `__init__` params (i.e. `_sa_session`). """ return EXT_PASS def load(self, query, *args, **kwargs): """Override the `load` method of the Query object. The return value of this method is used as the result of ``query.load()`` if the value is anything other than EXT_PASS. """ return EXT_PASS def get(self, query, *args, **kwargs): """Override the `get` method of the Query object. The return value of this method is used as the result of ``query.get()`` if the value is anything other than EXT_PASS. """ return EXT_PASS def get_by(self, query, *args, **kwargs): """Override the `get_by` method of the Query object. The return value of this method is used as the result of ``query.get_by()`` if the value is anything other than EXT_PASS. """ return EXT_PASS def select_by(self, query, *args, **kwargs): """Override the `select_by` method of the Query object. The return value of this method is used as the result of ``query.select_by()`` if the value is anything other than EXT_PASS. """ return EXT_PASS def select(self, query, *args, **kwargs): """Override the `select` method of the Query object. The return value of this method is used as the result of ``query.select()`` if the value is anything other than EXT_PASS. """ return EXT_PASS def translate_row(self, mapper, context, row): """Perform pre-processing on the given result row and return a new row instance. This is called as the very first step in the ``_instance()`` method. """ return EXT_PASS def create_instance(self, mapper, selectcontext, row, class_): """Receive a row when a new object instance is about to be created from that row. The method can choose to create the instance itself, or it can return None to indicate normal object creation should take place. mapper The mapper doing the operation selectcontext SelectionContext corresponding to the instances() call row The result row from the database class\_ The class we are mapping. """ return EXT_PASS def append_result(self, mapper, selectcontext, row, instance, identitykey, result, isnew): """Receive an object instance before that instance is appended to a result list. If this method returns EXT_PASS, result appending will proceed normally. if this method returns any other value or None, result appending will not proceed for this instance, giving this extension an opportunity to do the appending itself, if desired. mapper The mapper doing the operation. selectcontext SelectionContext corresponding to the instances() call. row The result row from the database. instance The object instance to be appended to the result. identitykey The identity key of the instance. result List to which results are being appended. isnew Indicates if this is the first time we have seen this object instance in the current result set. if you are selecting from a join, such as an eager load, you might see the same object instance many times in the same result set. """ return EXT_PASS def populate_instance(self, mapper, selectcontext, row, instance, identitykey, isnew): """Receive a newly-created instance before that instance has its attributes populated. The normal population of attributes is according to each attribute's corresponding MapperProperty (which includes column-based attributes as well as relationships to other classes). If this method returns EXT_PASS, instance population will proceed normally. If any other value or None is returned, instance population will not proceed, giving this extension an opportunity to populate the instance itself, if desired. """ return EXT_PASS def before_insert(self, mapper, connection, instance): """Receive an object instance before that instance is INSERTed into its table. This is a good place to set up primary key values and such that aren't handled otherwise. """ return EXT_PASS def before_update(self, mapper, connection, instance): """Receive an object instance before that instance is UPDATEed.""" return EXT_PASS def after_update(self, mapper, connection, instance): """Receive an object instance after that instance is UPDATEed.""" return EXT_PASS def after_insert(self, mapper, connection, instance): """Receive an object instance after that instance is INSERTed.""" return EXT_PASS def before_delete(self, mapper, connection, instance): """Receive an object instance before that instance is DELETEed.""" return EXT_PASS def after_delete(self, mapper, connection, instance): """Receive an object instance after that instance is DELETEed.""" return EXT_PASS class _ExtensionCarrier(MapperExtension): def __init__(self): self.__elements = [] def __iter__(self): return iter(self.__elements) def insert(self, extension): """Insert a MapperExtension at the beginning of this ExtensionCarrier's list.""" self.__elements.insert(0, extension) def append(self, extension): """Append a MapperExtension at the end of this ExtensionCarrier's list.""" self.__elements.append(extension) def get_session(self, *args, **kwargs): return self._do('get_session', *args, **kwargs) def load(self, *args, **kwargs): return self._do('load', *args, **kwargs) def get(self, *args, **kwargs): return self._do('get', *args, **kwargs) def get_by(self, *args, **kwargs): return self._do('get_by', *args, **kwargs) def select_by(self, *args, **kwargs): return self._do('select_by', *args, **kwargs) def select(self, *args, **kwargs): return self._do('select', *args, **kwargs) def translate_row(self, *args, **kwargs): return self._do('translate_row', *args, **kwargs) def create_instance(self, *args, **kwargs): return self._do('create_instance', *args, **kwargs) def append_result(self, *args, **kwargs): return self._do('append_result', *args, **kwargs) def populate_instance(self, *args, **kwargs): return self._do('populate_instance', *args, **kwargs) def before_insert(self, *args, **kwargs): return self._do('before_insert', *args, **kwargs) def before_update(self, *args, **kwargs): return self._do('before_update', *args, **kwargs) def after_update(self, *args, **kwargs): return self._do('after_update', *args, **kwargs) def after_insert(self, *args, **kwargs): return self._do('after_insert', *args, **kwargs) def before_delete(self, *args, **kwargs): return self._do('before_delete', *args, **kwargs) def after_delete(self, *args, **kwargs): return self._do('after_delete', *args, **kwargs) def _do(self, funcname, *args, **kwargs): for elem in self.__elements: ret = getattr(elem, funcname)(*args, **kwargs) if ret is not EXT_PASS: return ret else: return EXT_PASS class ExtensionOption(MapperOption): def __init__(self, ext): self.ext = ext def process_query(self, query): query.extension.append(self.ext) class ClassKey(object): """Key a class and an entity name to a mapper, via the mapper_registry.""" __metaclass__ = util.ArgSingleton def __init__(self, class_, entity_name): self.class_ = class_ self.entity_name = entity_name def __hash__(self): return hash((self.class_, self.entity_name)) def __eq__(self, other): return self is other def __repr__(self): return "ClassKey(%s, %s)" % (repr(self.class_), repr(self.entity_name)) def dispose(self): type(self).dispose_static(self.class_, self.entity_name) def has_identity(object): return hasattr(object, '_instance_key') def has_mapper(object): """Return True if the given object has had a mapper association set up, either through loading, or via insertion in a session. """ return hasattr(object, '_entity_name') def object_mapper(object, entity_name=None, raiseerror=True): """Given an object, return the primary Mapper associated with the object instance. object The object instance. entity_name Entity name of the mapper to retrieve, if the given instance is transient. Otherwise uses the entity name already associated with the instance. raiseerror Defaults to True: raise an ``InvalidRequestError`` if no mapper can be located. If False, return None. """ try: mapper = mapper_registry[ClassKey(object.__class__, getattr(object, '_entity_name', entity_name))] except (KeyError, AttributeError): if raiseerror: raise exceptions.InvalidRequestError("Class '%s' entity name '%s' has no mapper associated with it" % (object.__class__.__name__, getattr(object, '_entity_name', entity_name))) else: return None return mapper.compile() def class_mapper(class_, entity_name=None, compile=True): """Given a class and optional entity_name, return the primary Mapper associated with the key. If no mapper can be located, raises ``InvalidRequestError``. """ try: mapper = mapper_registry[ClassKey(class_, entity_name)] except (KeyError, AttributeError): raise exceptions.InvalidRequestError("Class '%s' entity name '%s' has no mapper associated with it" % (class_.__name__, entity_name)) if compile: return mapper.compile() else: return mapper