def before_drop(self, target, connection, **kw):
"""Called before DROP statements are emitted.
:param target: the :class:`.MetaData` or :class:`.Table`
object which is the target of the event.
:param connection: the :class:`.Connection` where the
DROP statement or statements will be emitted.
:param \**kw: additional keyword arguments relevant
to the event. The contents of this dictionary
may vary across releases, and include the
list of tables being generated for a metadata-level
event, the checkfirst flag, and other
elements used by internal events.
"""
python类Table()的实例源码
def after_drop(self, target, connection, **kw):
"""Called after DROP statements are emitted.
:param target: the :class:`.MetaData` or :class:`.Table`
object which is the target of the event.
:param connection: the :class:`.Connection` where the
DROP statement or statements have been emitted.
:param \**kw: additional keyword arguments relevant
to the event. The contents of this dictionary
may vary across releases, and include the
list of tables being generated for a metadata-level
event, the checkfirst flag, and other
elements used by internal events.
"""
def before_parent_attach(self, target, parent):
"""Called before a :class:`.SchemaItem` is associated with
a parent :class:`.SchemaItem`.
:param target: the target object
:param parent: the parent to which the target is being attached.
:func:`.event.listen` also accepts a modifier for this event:
:param propagate=False: When True, the listener function will
be established for any copies made of the target object,
i.e. those copies that are generated when
:meth:`.Table.tometadata` is used.
"""
def _primary_key_constraint(self, name, table_name, cols, schema=None):
m = sa_schema.MetaData()
columns = [sa_schema.Column(n, NULLTYPE) for n in cols]
t1 = sa_schema.Table(table_name, m,
*columns,
schema=schema)
p = sa_schema.PrimaryKeyConstraint(*columns, name=name)
t1.append_constraint(p)
return p
def _foreign_key_constraint(self, name, source, referent,
local_cols, remote_cols,
onupdate=None, ondelete=None,
deferrable=None, source_schema=None,
referent_schema=None):
m = sa_schema.MetaData()
if source == referent:
t1_cols = local_cols + remote_cols
else:
t1_cols = local_cols
sa_schema.Table(referent, m,
*[sa_schema.Column(n, NULLTYPE) for n in remote_cols],
schema=referent_schema)
t1 = sa_schema.Table(source, m,
*[sa_schema.Column(n, NULLTYPE) for n in t1_cols],
schema=source_schema)
tname = "%s.%s" % (referent_schema, referent) if referent_schema \
else referent
f = sa_schema.ForeignKeyConstraint(local_cols,
["%s.%s" % (tname, n)
for n in remote_cols],
name=name,
onupdate=onupdate,
ondelete=ondelete,
deferrable=deferrable
)
t1.append_constraint(f)
return f
def _unique_constraint(self, name, source, local_cols, schema=None, **kw):
t = sa_schema.Table(source, sa_schema.MetaData(),
*[sa_schema.Column(n, NULLTYPE) for n in local_cols],
schema=schema)
kw['name'] = name
uq = sa_schema.UniqueConstraint(*[t.c[n] for n in local_cols], **kw)
# TODO: need event tests to ensure the event
# is fired off here
t.append_constraint(uq)
return uq
def _table(self, name, *columns, **kw):
m = sa_schema.MetaData()
t = sa_schema.Table(name, m, *columns, **kw)
for f in t.foreign_keys:
self._ensure_table_for_fk(m, f)
return t
def _index(self, name, tablename, columns, schema=None, **kw):
t = sa_schema.Table(tablename or 'no_table', sa_schema.MetaData(),
*[sa_schema.Column(n, NULLTYPE) for n in columns],
schema=schema
)
return sa_schema.Index(name, *[t.c[n] for n in columns], **kw)
def _ensure_table_for_fk(self, metadata, fk):
"""create a placeholder Table object for the referent of a
ForeignKey.
"""
if isinstance(fk._colspec, string_types):
table_key, cname = fk._colspec.rsplit('.', 1)
sname, tname = self._parse_table_key(table_key)
if table_key not in metadata.tables:
rel_t = sa_schema.Table(tname, metadata, schema=sname)
else:
rel_t = metadata.tables[table_key]
if cname not in rel_t.c:
rel_t.append_column(sa_schema.Column(cname, NULLTYPE))
def create_primary_key(self, name, table_name, cols, schema=None):
"""Issue a "create primary key" instruction using the current
migration context.
e.g.::
from alembic import op
op.create_primary_key(
"pk_my_table", "my_table",
["id", "version"]
)
This internally generates a :class:`~sqlalchemy.schema.Table` object
containing the necessary columns, then generates a new
:class:`~sqlalchemy.schema.PrimaryKeyConstraint`
object which it then associates with the :class:`~sqlalchemy.schema.Table`.
Any event listeners associated with this action will be fired
off normally. The :class:`~sqlalchemy.schema.AddConstraint`
construct is ultimately used to generate the ALTER statement.
.. versionadded:: 0.5.0
:param name: Name of the primary key constraint. The name is necessary
so that an ALTER statement can be emitted. For setups that
use an automated naming scheme such as that described at
`NamingConventions <http://www.sqlalchemy.org/trac/wiki/UsageRecipes/NamingConventions>`_,
``name`` here can be ``None``, as the event listener will
apply the name to the constraint object when it is associated
with the table.
:param table_name: String name of the target table.
:param cols: a list of string column names to be applied to the
primary key constraint.
:param schema: Optional schema name of the table.
"""
self.impl.add_constraint(
self._primary_key_constraint(name, table_name, cols,
schema)
)
def before_create(self, target, connection, **kw):
"""Called before CREATE statements are emitted.
:param target: the :class:`.MetaData` or :class:`.Table`
object which is the target of the event.
:param connection: the :class:`.Connection` where the
CREATE statement or statements will be emitted.
:param \**kw: additional keyword arguments relevant
to the event. The contents of this dictionary
may vary across releases, and include the
list of tables being generated for a metadata-level
event, the checkfirst flag, and other
elements used by internal events.
"""
def after_create(self, target, connection, **kw):
"""Called after CREATE statements are emitted.
:param target: the :class:`.MetaData` or :class:`.Table`
object which is the target of the event.
:param connection: the :class:`.Connection` where the
CREATE statement or statements have been emitted.
:param \**kw: additional keyword arguments relevant
to the event. The contents of this dictionary
may vary across releases, and include the
list of tables being generated for a metadata-level
event, the checkfirst flag, and other
elements used by internal events.
"""
def before_drop(self, target, connection, **kw):
"""Called before DROP statements are emitted.
:param target: the :class:`.MetaData` or :class:`.Table`
object which is the target of the event.
:param connection: the :class:`.Connection` where the
DROP statement or statements will be emitted.
:param \**kw: additional keyword arguments relevant
to the event. The contents of this dictionary
may vary across releases, and include the
list of tables being generated for a metadata-level
event, the checkfirst flag, and other
elements used by internal events.
"""
def after_drop(self, target, connection, **kw):
"""Called after DROP statements are emitted.
:param target: the :class:`.MetaData` or :class:`.Table`
object which is the target of the event.
:param connection: the :class:`.Connection` where the
DROP statement or statements have been emitted.
:param \**kw: additional keyword arguments relevant
to the event. The contents of this dictionary
may vary across releases, and include the
list of tables being generated for a metadata-level
event, the checkfirst flag, and other
elements used by internal events.
"""
def before_parent_attach(self, target, parent):
"""Called before a :class:`.SchemaItem` is associated with
a parent :class:`.SchemaItem`.
:param target: the target object
:param parent: the parent to which the target is being attached.
:func:`.event.listen` also accepts a modifier for this event:
:param propagate=False: When True, the listener function will
be established for any copies made of the target object,
i.e. those copies that are generated when
:meth:`.Table.tometadata` is used.
"""
def before_create(self, target, connection, **kw):
"""Called before CREATE statements are emitted.
:param target: the :class:`.MetaData` or :class:`.Table`
object which is the target of the event.
:param connection: the :class:`.Connection` where the
CREATE statement or statements will be emitted.
:param \**kw: additional keyword arguments relevant
to the event. The contents of this dictionary
may vary across releases, and include the
list of tables being generated for a metadata-level
event, the checkfirst flag, and other
elements used by internal events.
"""
def after_create(self, target, connection, **kw):
"""Called after CREATE statements are emitted.
:param target: the :class:`.MetaData` or :class:`.Table`
object which is the target of the event.
:param connection: the :class:`.Connection` where the
CREATE statement or statements have been emitted.
:param \**kw: additional keyword arguments relevant
to the event. The contents of this dictionary
may vary across releases, and include the
list of tables being generated for a metadata-level
event, the checkfirst flag, and other
elements used by internal events.
"""
def before_drop(self, target, connection, **kw):
"""Called before DROP statements are emitted.
:param target: the :class:`.MetaData` or :class:`.Table`
object which is the target of the event.
:param connection: the :class:`.Connection` where the
DROP statement or statements will be emitted.
:param \**kw: additional keyword arguments relevant
to the event. The contents of this dictionary
may vary across releases, and include the
list of tables being generated for a metadata-level
event, the checkfirst flag, and other
elements used by internal events.
"""
def after_drop(self, target, connection, **kw):
"""Called after DROP statements are emitted.
:param target: the :class:`.MetaData` or :class:`.Table`
object which is the target of the event.
:param connection: the :class:`.Connection` where the
DROP statement or statements have been emitted.
:param \**kw: additional keyword arguments relevant
to the event. The contents of this dictionary
may vary across releases, and include the
list of tables being generated for a metadata-level
event, the checkfirst flag, and other
elements used by internal events.
"""
def before_parent_attach(self, target, parent):
"""Called before a :class:`.SchemaItem` is associated with
a parent :class:`.SchemaItem`.
:param target: the target object
:param parent: the parent to which the target is being attached.
:func:`.event.listen` also accepts a modifier for this event:
:param propagate=False: When True, the listener function will
be established for any copies made of the target object,
i.e. those copies that are generated when
:meth:`.Table.tometadata` is used.
"""
