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author | Mike Bayer <mike_mp@zzzcomputing.com> | 2012-07-16 17:29:02 -0400 |
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committer | Mike Bayer <mike_mp@zzzcomputing.com> | 2012-07-16 17:29:02 -0400 |
commit | ce9a702dbd52946487f45b98ef20d1b7783facb6 (patch) | |
tree | 7273a1982850bf9975509295d766053d4fe822b1 /lib/sqlalchemy/ext/declarative.py | |
parent | 1dc09bf6ede97ef08b2c8c0886a03b44bba735ff (diff) | |
download | sqlalchemy-ce9a702dbd52946487f45b98ef20d1b7783facb6.tar.gz |
- express most of the orm.util functions in terms of the inspection system
- modify inspection system:
1. raise a new exception for any case where the inspection
context can't be returned. this supersedes the "not mapped"
errors.
2. don't configure mappers on a mapper inspection. this allows
the inspectors to be used during mapper config time. instead,
the mapper configures on "with_polymorphic_selectable" now,
which is needed for all queries
- add a bunch of new "is_XYZ" attributes to inspectors
- finish making the name change of "compile" -> "configure", for some reason
this was only done partially
Diffstat (limited to 'lib/sqlalchemy/ext/declarative.py')
-rwxr-xr-x | lib/sqlalchemy/ext/declarative.py | 202 |
1 files changed, 101 insertions, 101 deletions
diff --git a/lib/sqlalchemy/ext/declarative.py b/lib/sqlalchemy/ext/declarative.py index 651a94970..ea0367d72 100755 --- a/lib/sqlalchemy/ext/declarative.py +++ b/lib/sqlalchemy/ext/declarative.py @@ -51,7 +51,7 @@ automatically named with the name of the attribute to which they are assigned. To name columns explicitly with a name distinct from their mapped attribute, -just give the column a name. Below, column "some_table_id" is mapped to the +just give the column a name. Below, column "some_table_id" is mapped to the "id" attribute of `SomeClass`, but in SQL will be represented as "some_table_id":: class SomeClass(Base): @@ -68,7 +68,7 @@ added to the underlying :class:`.Table` and Classes which are constructed using declarative can interact freely with classes that are mapped explicitly with :func:`mapper`. -It is recommended, though not required, that all tables +It is recommended, though not required, that all tables share the same underlying :class:`~sqlalchemy.schema.MetaData` object, so that string-configured :class:`~sqlalchemy.schema.ForeignKey` references can be resolved without issue. @@ -98,9 +98,9 @@ of construction, the ``bind`` argument is accepted:: :func:`declarative_base` can also receive a pre-existing :class:`.MetaData` object, which allows a -declarative setup to be associated with an already +declarative setup to be associated with an already existing traditional collection of :class:`~sqlalchemy.schema.Table` -objects:: +objects:: mymetadata = MetaData() Base = declarative_base(metadata=mymetadata) @@ -113,7 +113,7 @@ feature that the class specified to :func:`~sqlalchemy.orm.relationship` may be a string name. The "class registry" associated with ``Base`` is used at mapper compilation time to resolve the name into the actual class object, which is expected to have been defined once the mapper -configuration is used:: +configuration is used:: class User(Base): __tablename__ = 'users' @@ -131,7 +131,7 @@ configuration is used:: Column constructs, since they are just that, are immediately usable, as below where we define a primary join condition on the ``Address`` -class using them:: +class using them:: class Address(Base): __tablename__ = 'addresses' @@ -148,15 +148,15 @@ evaluated as Python expressions. The full namespace available within this evaluation includes all classes mapped for this declarative base, as well as the contents of the ``sqlalchemy`` package, including expression functions like :func:`~sqlalchemy.sql.expression.desc` and -:attr:`~sqlalchemy.sql.expression.func`:: +:attr:`~sqlalchemy.sql.expression.func`:: class User(Base): # .... addresses = relationship("Address", - order_by="desc(Address.email)", + order_by="desc(Address.email)", primaryjoin="Address.user_id==User.id") -As an alternative to string-based attributes, attributes may also be +As an alternative to string-based attributes, attributes may also be defined after all classes have been created. Just add them to the target class after the fact:: @@ -169,8 +169,8 @@ Configuring Many-to-Many Relationships Many-to-many relationships are also declared in the same way with declarative as with traditional mappings. The ``secondary`` argument to -:func:`.relationship` is as usual passed a -:class:`.Table` object, which is typically declared in the +:func:`.relationship` is as usual passed a +:class:`.Table` object, which is typically declared in the traditional way. The :class:`.Table` usually shares the :class:`.MetaData` object used by the declarative base:: @@ -185,7 +185,7 @@ the :class:`.MetaData` object used by the declarative base:: id = Column(Integer, primary_key=True) keywords = relationship("Keyword", secondary=keywords) -Like other :func:`.relationship` arguments, a string is accepted as well, +Like other :func:`.relationship` arguments, a string is accepted as well, passing the string name of the table as defined in the ``Base.metadata.tables`` collection:: @@ -194,7 +194,7 @@ collection:: id = Column(Integer, primary_key=True) keywords = relationship("Keyword", secondary="keywords") -As with traditional mapping, its generally not a good idea to use +As with traditional mapping, its generally not a good idea to use a :class:`.Table` as the "secondary" argument which is also mapped to a class, unless the :class:`.relationship` is declared with ``viewonly=True``. Otherwise, the unit-of-work system may attempt duplicate INSERT and @@ -219,7 +219,7 @@ This attribute accommodates both positional as well as keyword arguments that are normally sent to the :class:`~sqlalchemy.schema.Table` constructor. The attribute can be specified in one of two forms. One is as a -dictionary:: +dictionary:: class MyClass(Base): __tablename__ = 'sometable' @@ -235,7 +235,7 @@ The other, a tuple, where each argument is positional UniqueConstraint('foo'), ) -Keyword arguments can be specified with the above form by +Keyword arguments can be specified with the above form by specifying the last argument as a dictionary:: class MyClass(Base): @@ -253,7 +253,7 @@ As an alternative to ``__tablename__``, a direct :class:`~sqlalchemy.schema.Table` construct may be used. The :class:`~sqlalchemy.schema.Column` objects, which in this case require their names, will be added to the mapping just like a regular mapping -to a table:: +to a table:: class MyClass(Base): __table__ = Table('my_table', Base.metadata, @@ -277,9 +277,9 @@ and pass it to declarative classes:: class Address(Base): __table__ = metadata.tables['address'] -Some configuration schemes may find it more appropriate to use ``__table__``, -such as those which already take advantage of the data-driven nature of -:class:`.Table` to customize and/or automate schema definition. +Some configuration schemes may find it more appropriate to use ``__table__``, +such as those which already take advantage of the data-driven nature of +:class:`.Table` to customize and/or automate schema definition. Note that when the ``__table__`` approach is used, the object is immediately usable as a plain :class:`.Table` within the class declaration body itself, @@ -292,10 +292,10 @@ by using the ``id`` column in the ``primaryjoin`` condition of a :func:`.relatio Column('name', String(50)) ) - widgets = relationship(Widget, + widgets = relationship(Widget, primaryjoin=Widget.myclass_id==__table__.c.id) -Similarly, mapped attributes which refer to ``__table__`` can be placed inline, +Similarly, mapped attributes which refer to ``__table__`` can be placed inline, as below where we assign the ``name`` column to the attribute ``_name``, generating a synonym for ``name``:: @@ -320,13 +320,13 @@ It's easy to set up a :class:`.Table` that uses ``autoload=True`` in conjunction with a mapped class:: class MyClass(Base): - __table__ = Table('mytable', Base.metadata, + __table__ = Table('mytable', Base.metadata, autoload=True, autoload_with=some_engine) -However, one improvement that can be made here is to not -require the :class:`.Engine` to be available when classes are +However, one improvement that can be made here is to not +require the :class:`.Engine` to be available when classes are being first declared. To achieve this, use the -:class:`.DeferredReflection` mixin, which sets up mappings +:class:`.DeferredReflection` mixin, which sets up mappings only after a special ``prepare(engine)`` step is called:: from sqlalchemy.ext.declarative import declarative_base, DeferredReflection @@ -340,7 +340,7 @@ only after a special ``prepare(engine)`` step is called:: class Bar(Base): __tablename__ = 'bar' - # illustrate overriding of "bar.foo_id" to have + # illustrate overriding of "bar.foo_id" to have # a foreign key constraint otherwise not # reflected, such as when using MySQL foo_id = Column(Integer, ForeignKey('foo.id')) @@ -357,7 +357,7 @@ Declarative makes use of the :func:`~.orm.mapper` function internally when it creates the mapping to the declared table. The options for :func:`~.orm.mapper` are passed directly through via the ``__mapper_args__`` class attribute. As always, arguments which reference locally -mapped columns can reference them directly from within the +mapped columns can reference them directly from within the class declaration:: from datetime import datetime @@ -386,7 +386,7 @@ as declarative will determine this from the class itself. The various Joined Table Inheritance ~~~~~~~~~~~~~~~~~~~~~~~~ -Joined table inheritance is defined as a subclass that defines its own +Joined table inheritance is defined as a subclass that defines its own table:: class Person(Base): @@ -419,13 +419,13 @@ only the ``engineers.id`` column, give it a different attribute name:: .. versionchanged:: 0.7 joined table inheritance favors the subclass column over that of the superclass, such as querying above for ``Engineer.id``. Prior to 0.7 this was the reverse. - + Single Table Inheritance ~~~~~~~~~~~~~~~~~~~~~~~~ Single table inheritance is defined as a subclass that does not have its own table; you just leave out the ``__table__`` and ``__tablename__`` -attributes:: +attributes:: class Person(Base): __tablename__ = 'people' @@ -536,7 +536,7 @@ To have a concrete ``employee`` table, use :class:`.ConcreteBase` instead:: employee_id = Column(Integer, primary_key=True) name = Column(String(50)) __mapper_args__ = { - 'polymorphic_identity':'employee', + 'polymorphic_identity':'employee', 'concrete':True} @@ -548,7 +548,7 @@ Either ``Employee`` base can be used in the normal fashion:: name = Column(String(50)) manager_data = Column(String(40)) __mapper_args__ = { - 'polymorphic_identity':'manager', + 'polymorphic_identity':'manager', 'concrete':True} class Engineer(Employee): @@ -556,7 +556,7 @@ Either ``Employee`` base can be used in the normal fashion:: employee_id = Column(Integer, primary_key=True) name = Column(String(50)) engineer_info = Column(String(40)) - __mapper_args__ = {'polymorphic_identity':'engineer', + __mapper_args__ = {'polymorphic_identity':'engineer', 'concrete':True} @@ -596,29 +596,29 @@ idioms is below:: Where above, the class ``MyModel`` will contain an "id" column as the primary key, a ``__tablename__`` attribute that derives -from the name of the class itself, as well as ``__table_args__`` +from the name of the class itself, as well as ``__table_args__`` and ``__mapper_args__`` defined by the ``MyMixin`` mixin class. -There's no fixed convention over whether ``MyMixin`` precedes -``Base`` or not. Normal Python method resolution rules apply, and +There's no fixed convention over whether ``MyMixin`` precedes +``Base`` or not. Normal Python method resolution rules apply, and the above example would work just as well with:: class MyModel(Base, MyMixin): name = Column(String(1000)) -This works because ``Base`` here doesn't define any of the -variables that ``MyMixin`` defines, i.e. ``__tablename__``, -``__table_args__``, ``id``, etc. If the ``Base`` did define -an attribute of the same name, the class placed first in the -inherits list would determine which attribute is used on the +This works because ``Base`` here doesn't define any of the +variables that ``MyMixin`` defines, i.e. ``__tablename__``, +``__table_args__``, ``id``, etc. If the ``Base`` did define +an attribute of the same name, the class placed first in the +inherits list would determine which attribute is used on the newly defined class. Augmenting the Base ~~~~~~~~~~~~~~~~~~~ -In addition to using a pure mixin, most of the techniques in this +In addition to using a pure mixin, most of the techniques in this section can also be applied to the base class itself, for patterns that -should apply to all classes derived from a particular base. This +should apply to all classes derived from a particular base. This is achieved using the ``cls`` argument of the :func:`.declarative_base` function:: from sqlalchemy.ext.declarative import declared_attr @@ -639,14 +639,14 @@ is achieved using the ``cls`` argument of the :func:`.declarative_base` function class MyModel(Base): name = Column(String(1000)) -Where above, ``MyModel`` and all other classes that derive from ``Base`` will have -a table name derived from the class name, an ``id`` primary key column, as well as +Where above, ``MyModel`` and all other classes that derive from ``Base`` will have +a table name derived from the class name, an ``id`` primary key column, as well as the "InnoDB" engine for MySQL. Mixing in Columns ~~~~~~~~~~~~~~~~~ -The most basic way to specify a column on a mixin is by simple +The most basic way to specify a column on a mixin is by simple declaration:: class TimestampMixin(object): @@ -659,26 +659,26 @@ declaration:: name = Column(String(1000)) Where above, all declarative classes that include ``TimestampMixin`` -will also have a column ``created_at`` that applies a timestamp to +will also have a column ``created_at`` that applies a timestamp to all row insertions. -Those familiar with the SQLAlchemy expression language know that +Those familiar with the SQLAlchemy expression language know that the object identity of clause elements defines their role in a schema. -Two ``Table`` objects ``a`` and ``b`` may both have a column called -``id``, but the way these are differentiated is that ``a.c.id`` +Two ``Table`` objects ``a`` and ``b`` may both have a column called +``id``, but the way these are differentiated is that ``a.c.id`` and ``b.c.id`` are two distinct Python objects, referencing their parent tables ``a`` and ``b`` respectively. In the case of the mixin column, it seems that only one -:class:`.Column` object is explicitly created, yet the ultimate +:class:`.Column` object is explicitly created, yet the ultimate ``created_at`` column above must exist as a distinct Python object for each separate destination class. To accomplish this, the declarative -extension creates a **copy** of each :class:`.Column` object encountered on +extension creates a **copy** of each :class:`.Column` object encountered on a class that is detected as a mixin. This copy mechanism is limited to simple columns that have no foreign keys, as a :class:`.ForeignKey` itself contains references to columns -which can't be properly recreated at this level. For columns that +which can't be properly recreated at this level. For columns that have foreign keys, as well as for the variety of mapper-level constructs that require destination-explicit context, the :func:`~.declared_attr` decorator is provided so that @@ -695,7 +695,7 @@ patterns common to many classes can be defined as callables:: __tablename__ = 'user' id = Column(Integer, primary_key=True) -Where above, the ``address_id`` class-level callable is executed at the +Where above, the ``address_id`` class-level callable is executed at the point at which the ``User`` class is constructed, and the declarative extension can use the resulting :class:`.Column` object as returned by the method without the need to copy it. @@ -704,8 +704,8 @@ the method without the need to copy it. Rename 0.6.5 ``sqlalchemy.util.classproperty`` into :func:`~.declared_attr`. Columns generated by :func:`~.declared_attr` can also be -referenced by ``__mapper_args__`` to a limited degree, currently -by ``polymorphic_on`` and ``version_id_col``, by specifying the +referenced by ``__mapper_args__`` to a limited degree, currently +by ``polymorphic_on`` and ``version_id_col``, by specifying the classdecorator itself into the dictionary - the declarative extension will resolve them at class construction time:: @@ -753,7 +753,7 @@ reference a common target class via many-to-one:: id = Column(Integer, primary_key=True) :func:`~sqlalchemy.orm.relationship` definitions which require explicit -primaryjoin, order_by etc. expressions should use the string forms +primaryjoin, order_by etc. expressions should use the string forms for these arguments, so that they are evaluated as late as possible. To reference the mixin class in these expressions, use the given ``cls`` to get it's name:: @@ -775,8 +775,8 @@ Mixing in deferred(), column_property(), etc. Like :func:`~sqlalchemy.orm.relationship`, all :class:`~sqlalchemy.orm.interfaces.MapperProperty` subclasses such as :func:`~sqlalchemy.orm.deferred`, :func:`~sqlalchemy.orm.column_property`, -etc. ultimately involve references to columns, and therefore, when -used with declarative mixins, have the :func:`.declared_attr` +etc. ultimately involve references to columns, and therefore, when +used with declarative mixins, have the :func:`.declared_attr` requirement so that no reliance on copying is needed:: class SomethingMixin(object): @@ -793,7 +793,7 @@ Controlling table inheritance with mixins ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The ``__tablename__`` attribute in conjunction with the hierarchy of -classes involved in a declarative mixin scenario controls what type of +classes involved in a declarative mixin scenario controls what type of table inheritance, if any, is configured by the declarative extension. @@ -828,7 +828,7 @@ return a ``__tablename__`` in the event that no table is already mapped in the inheritance hierarchy. To help with this, a :func:`~sqlalchemy.ext.declarative.has_inherited_table` helper function is provided that returns ``True`` if a parent class already -has a mapped table. +has a mapped table. As an example, here's a mixin that will only allow single table inheritance:: @@ -918,7 +918,7 @@ from multiple collections:: Creating Indexes with Mixins ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -To define a named, potentially multicolumn :class:`.Index` that applies to all +To define a named, potentially multicolumn :class:`.Index` that applies to all tables derived from a mixin, use the "inline" form of :class:`.Index` and establish it as part of ``__table_args__``:: @@ -940,7 +940,7 @@ Special Directives ``__declare_last__()`` ~~~~~~~~~~~~~~~~~~~~~~ -The ``__declare_last__()`` hook allows definition of +The ``__declare_last__()`` hook allows definition of a class level function that is automatically called by the :meth:`.MapperEvents.after_configured` event, which occurs after mappings are assumed to be completed and the 'configure' step has finished:: @@ -989,7 +989,7 @@ bases:: __abstract__ = True metadata = MetaData() -Above, classes which inherit from ``DefaultBase`` will use one :class:`.MetaData` as the +Above, classes which inherit from ``DefaultBase`` will use one :class:`.MetaData` as the registry of tables, and those which inherit from ``OtherBase`` will use a different one. The tables themselves can then be created perhaps within distinct databases:: @@ -1022,7 +1022,7 @@ setup using :func:`~sqlalchemy.orm.scoped_session` might look like:: Base = declarative_base() Mapped instances then make usage of -:class:`~sqlalchemy.orm.session.Session` in the usual way. +:class:`~sqlalchemy.orm.session.Session` in the usual way. """ @@ -1047,14 +1047,14 @@ def _declared_mapping_info(cls): return _MapperConfig.configs[cls] # regular mapping elif _is_mapped_class(cls): - return class_mapper(cls, compile=False) + return class_mapper(cls, configure=False) else: return None def instrument_declarative(cls, registry, metadata): """Given a class, configure the class declaratively, using the given registry, which can be any dictionary, and - MetaData object. + MetaData object. """ if '_decl_class_registry' in cls.__dict__: @@ -1097,7 +1097,7 @@ def _as_declarative(cls, classname, dict_): def go(): cls.__declare_last__() if '__abstract__' in base.__dict__: - if (base is cls or + if (base is cls or (base in cls.__bases__ and not _is_declarative_inherits) ): return @@ -1109,7 +1109,7 @@ def _as_declarative(cls, classname, dict_): for name,obj in vars(base).items(): if name == '__mapper_args__': if not mapper_args_fn and ( - not class_mapped or + not class_mapped or isinstance(obj, declarative_props) ): # don't even invoke __mapper_args__ until @@ -1118,13 +1118,13 @@ def _as_declarative(cls, classname, dict_): mapper_args_fn = lambda: cls.__mapper_args__ elif name == '__tablename__': if not tablename and ( - not class_mapped or + not class_mapped or isinstance(obj, declarative_props) ): tablename = cls.__tablename__ elif name == '__table_args__': if not table_args and ( - not class_mapped or + not class_mapped or isinstance(obj, declarative_props) ): table_args = cls.__table_args__ @@ -1139,7 +1139,7 @@ def _as_declarative(cls, classname, dict_): util.warn("Regular (i.e. not __special__) " "attribute '%s.%s' uses @declared_attr, " "but owning class %s is mapped - " - "not applying to subclass %s." + "not applying to subclass %s." % (base.__name__, name, base, cls)) continue elif base is not cls: @@ -1151,7 +1151,7 @@ def _as_declarative(cls, classname, dict_): "must be declared as @declared_attr callables " "on declarative mixin classes. ") if name not in dict_ and not ( - '__table__' in dict_ and + '__table__' in dict_ and (obj.name or name) in dict_['__table__'].c ) and name not in potential_columns: potential_columns[name] = \ @@ -1231,7 +1231,7 @@ def _as_declarative(cls, classname, dict_): elif isinstance(c, Column): _undefer_column_name(key, c) declared_columns.add(c) - # if the column is the same name as the key, + # if the column is the same name as the key, # remove it from the explicit properties dict. # the normal rules for assigning column-based properties # will take over, including precedence of columns @@ -1317,17 +1317,17 @@ def _as_declarative(cls, classname, dict_): if c.name in inherited_table.c: raise exc.ArgumentError( "Column '%s' on class %s conflicts with " - "existing column '%s'" % + "existing column '%s'" % (c, cls, inherited_table.c[c.name]) ) inherited_table.append_column(c) - mt = _MapperConfig(mapper_cls, + mt = _MapperConfig(mapper_cls, cls, table, inherits, - declared_columns, + declared_columns, column_copies, - our_stuff, + our_stuff, mapper_args_fn) if not hasattr(cls, '_sa_decl_prepare'): mt.map() @@ -1335,9 +1335,9 @@ def _as_declarative(cls, classname, dict_): class _MapperConfig(object): configs = util.OrderedDict() - def __init__(self, mapper_cls, - cls, - table, + def __init__(self, mapper_cls, + cls, + table, inherits, declared_columns, column_copies, @@ -1361,7 +1361,7 @@ class _MapperConfig(object): else: mapper_args = {} - # make sure that column copies are used rather + # make sure that column copies are used rather # than the original columns from any mixins for k in ('version_id_col', 'polymorphic_on',): if k in mapper_args: @@ -1376,7 +1376,7 @@ class _MapperConfig(object): if self.inherits and not mapper_args.get('concrete', False): # single or joined inheritance - # exclude any cols on the inherited table which are + # exclude any cols on the inherited table which are # not mapped on the parent class, to avoid # mapping columns specific to sibling/nephew classes inherited_mapper = _declared_mapping_info(self.inherits) @@ -1389,7 +1389,7 @@ class _MapperConfig(object): exclude_properties.difference_update( [c.key for c in self.declared_columns]) - # look through columns in the current mapper that + # look through columns in the current mapper that # are keyed to a propname different than the colname # (if names were the same, we'd have popped it out above, # in which case the mapper makes this combination). @@ -1440,7 +1440,7 @@ class DeclarativeMeta(type): cls.__mapper__.add_property(key, value) elif isinstance(value, MapperProperty): cls.__mapper__.add_property( - key, + key, _deferred_relationship(cls, value) ) else: @@ -1454,7 +1454,7 @@ class _GetColumns(object): self.cls = cls def __getattr__(self, key): - mapper = class_mapper(self.cls, compile=False) + mapper = class_mapper(self.cls, configure=False) if mapper: if not mapper.has_property(key): raise exc.InvalidRequestError( @@ -1511,7 +1511,7 @@ def _deferred_relationship(cls, prop): "When initializing mapper %s, expression %r failed to " "locate a name (%r). If this is a class name, consider " "adding this relationship() to the %r class after " - "both dependent classes have been defined." % + "both dependent classes have been defined." % (prop.parent, arg, n.args[0], cls) ) return return_cls @@ -1582,13 +1582,13 @@ class declared_attr(property): a mapped property or special declarative member name. .. versionchanged:: 0.6.{2,3,4} - ``@declared_attr`` is available as + ``@declared_attr`` is available as ``sqlalchemy.util.classproperty`` for SQLAlchemy versions 0.6.2, 0.6.3, 0.6.4. @declared_attr turns the attribute into a scalar-like property that can be invoked from the uninstantiated class. - Declarative treats attributes specifically marked with + Declarative treats attributes specifically marked with @declared_attr as returning a construct that is specific to mapping or declarative table configuration. The name of the attribute is that of what the non-dynamic version @@ -1620,7 +1620,7 @@ class declared_attr(property): def __mapper_args__(cls): if cls.__name__ == 'Employee': return { - "polymorphic_on":cls.type, + "polymorphic_on":cls.type, "polymorphic_identity":"Employee" } else: @@ -1668,8 +1668,8 @@ def declarative_base(bind=None, metadata=None, mapper=None, cls=object, :param bind: An optional :class:`~sqlalchemy.engine.base.Connectable`, will be assigned - the ``bind`` attribute on the :class:`~sqlalchemy.MetaData` - instance. + the ``bind`` attribute on the :class:`~sqlalchemy.MetaData` + instance. :param metadata: An optional :class:`~sqlalchemy.MetaData` instance. All @@ -1700,11 +1700,11 @@ def declarative_base(bind=None, metadata=None, mapper=None, cls=object, no __init__ will be provided and construction will fall back to cls.__init__ by way of the normal Python semantics. - :param class_registry: optional dictionary that will serve as the + :param class_registry: optional dictionary that will serve as the registry of class names-> mapped classes when string names - are used to identify classes inside of :func:`.relationship` + are used to identify classes inside of :func:`.relationship` and others. Allows two or more declarative base classes - to share the same registry of class names for simplified + to share the same registry of class names for simplified inter-base relationships. :param metaclass: @@ -1759,7 +1759,7 @@ class ConcreteBase(object): employee_id = Column(Integer, primary_key=True) name = Column(String(50)) __mapper_args__ = { - 'polymorphic_identity':'employee', + 'polymorphic_identity':'employee', 'concrete':True} class Manager(Employee): @@ -1768,7 +1768,7 @@ class ConcreteBase(object): name = Column(String(50)) manager_data = Column(String(40)) __mapper_args__ = { - 'polymorphic_identity':'manager', + 'polymorphic_identity':'manager', 'concrete':True} """ @@ -1817,7 +1817,7 @@ class AbstractConcreteBase(ConcreteBase): name = Column(String(50)) manager_data = Column(String(40)) __mapper_args__ = { - 'polymorphic_identity':'manager', + 'polymorphic_identity':'manager', 'concrete':True} """ @@ -1851,7 +1851,7 @@ class AbstractConcreteBase(ConcreteBase): class DeferredReflection(object): - """A helper class for construction of mappings based on + """A helper class for construction of mappings based on a deferred reflection step. Normally, declarative can be used with reflection by @@ -1882,9 +1882,9 @@ class DeferredReflection(object): DeferredReflection.prepare(engine) The :class:`.DeferredReflection` mixin can be applied to individual - classes, used as the base for the declarative base itself, + classes, used as the base for the declarative base itself, or used in a custom abstract class. Using an abstract base - allows that only a subset of classes to be prepared for a + allows that only a subset of classes to be prepared for a particular prepare step, which is necessary for applications that use more than one engine. For example, if an application has two engines, you might use two bases, and prepare each |