Python alembic.op 模块，inline_literal() 实例源码
我们从Python开源项目中，提取了以下7个代码示例，用于说明如何使用alembic.op.inline_literal()。
def upgrade():
### commands auto generated by Alembic - please adjust! ###
query_tbl = sa.sql.table('query', sa.sql.column('platform', sa.String))
pack_tbl = sa.sql.table('pack', sa.String))
op.execute(
query_tbl.update() \
.where(
sa.or_(
query_tbl.c.platform==op.inline_literal('redhat,centos'),
query_tbl.c.platform==op.inline_literal('ubuntu'),
)
).values({'platform': op.inline_literal('linux')})
)
op.execute(
pack_tbl.update() \
.where(
sa.or_(
query_tbl.c.platform==op.inline_literal('redhat,
)
).values({'platform': op.inline_literal('linux')})
)
op.add_column('query', sa.Column('shard', sa.Integer(), nullable=True))
### end Alembic commands ###
def upgrade():
op.add_column("resource_type", sa.Column('tablename', sa.String(18),
nullable=True))
resource_type = sa.Table(
'resource_type', sa.MetaData(),
sa.Column('name', sa.String(255), nullable=False),
sa.Column('tablename', nullable=True)
)
op.execute(resource_type.update().where(
resource_type.c.name == "instance_network_interface"
).values({'tablename': op.inline_literal("'instance_net_int'")}))
op.execute(resource_type.update().where(
resource_type.c.name != "instance_network_interface"
).values({'tablename': resource_type.c.name}))
op.alter_column("resource_type", "tablename", type_=sa.String(18),
nullable=False)
op.create_unique_constraint("uniq_resource_type0tablename",
"resource_type", ["tablename"])
def upgrade(pyramid_env):
with context.begin_transaction():
op.drop_column('facebook_post', 'post_type')
op.drop_column('facebook_post', 'link_name')
# Could also alter column,but this operation has limitations
# (which we won't hit)
op.drop_column('facebook_post', 'attachment')
op.add_column('facebook_post', sa.Column('attachment_blob', sa.Binary))
op.add_column('facebook_source', sa.Column('lower_bound', sa.DateTime))
op.add_column('facebook_source', sa.Column('upper_bound', sa.DateTime))
# Do stuff with the app's models here.
from assembl import models as m
db = m.get_session_maker()()
with transaction.manager:
# Also correct the spelling mistake in attachment model.
a = m.Attachment.__table__
db.execute(
a.update().where(a.c.attachmentPurpose == op.inline_literal(
'EMBEEDED_ATTACHMENT')).
values(attachmentPurpose=op.inline_literal("EMBED_ATTACHMENT"))
)
def downgrade(pyramid_env):
with context.begin_transaction():
from assembl import models as m
db = m.get_session_maker()()
with transaction.manager:
# Undo correcting of the spelling mistake in attachment model.
a = m.Attachment.__table__
db.execute(
a.update().where(a.c.attachmentPurpose == op.inline_literal(
'EMBED_ATTACHMENT')).
values(attachmentPurpose=op.inline_literal(
"EMBEEDED_ATTACHMENT"))
)
op.drop_column('facebook_source', 'upper_bound')
op.drop_column('facebook_source', 'lower_bound')
op.drop_column('facebook_post', 'attachment_blob')
op.add_column('facebook_post', sa.Column('post_type', sa.String(20)))
op.add_column('facebook_post', sa.Column('link_name',
sa.Unicode(1024)))
op.add_column('facebook_post', sa.Column('attachment',
sa.String(1024)))
def inline_literal(self, value, type_=None):
"""Produce an 'inline literal' expression,suitable for
using in an INSERT,UPDATE,or DELETE statement.
When using Alembic in "offline" mode,CRUD operations
aren't compatible with SQLAlchemy's default behavior surrounding
literal values,
which is that they are converted into bound values and passed
separately into the ``execute()`` method of the DBAPI cursor.
An offline SQL
script needs to have these rendered inline. While it should
always be noted that inline literal values are an **enormous**
security hole in an application that handles untrusted input,
a schema migration is not run in this context,so
literals are safe to render inline,with the caveat that
advanced types like dates may not be supported directly
by SQLAlchemy.
See :meth:`.execute` for an example usage of
:meth:`.inline_literal`.
:param value: The value to render. Strings,integers,and simple
numerics should be supported. Other types like boolean,
dates,etc. may or may not be supported yet by various
backends.
:param ``type_``: optional - a :class:`sqlalchemy.types.TypeEngine`
subclass stating the type of this value. In SQLAlchemy
expressions,this is usually derived automatically
from the Python type of the value itself,as well as
based on the context in which the value is used.
"""
return impl._literal_bindparam(None, type_=type_)
def inline_literal(self,with the caveat that
advanced types like dates may not be supported directly
by SQLAlchemy.
See :meth:`.execute` for an example usage of
:meth:`.inline_literal`.
The environment can also be configured to attempt to render
"literal" values inline automatically,for those simple types
that are supported by the dialect; see
:paramref:`.EnvironmentContext.configure.literal_binds` for this
more recently added feature.
:param value: The value to render. Strings,as well as
based on the context in which the value is used.
.. seealso::
:paramref:`.EnvironmentContext.configure.literal_binds`
"""
return impl._literal_bindparam(None, type_=type_)
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