openmedialibrary_platform/Darwin/lib/python2.7/site-packages/alembic/autogenerate/api.py
2014-05-16 01:20:41 +02:00

301 lines
9.6 KiB
Python

"""Provide the 'autogenerate' feature which can produce migration operations
automatically."""
import logging
import re
from sqlalchemy.engine.reflection import Inspector
from sqlalchemy.util import OrderedSet
from .compare import _compare_tables
from .render import _drop_table, _drop_column, _drop_index, _drop_constraint, \
_add_table, _add_column, _add_index, _add_constraint, _modify_col
from .. import util
log = logging.getLogger(__name__)
###################################################
# public
def compare_metadata(context, metadata):
"""Compare a database schema to that given in a
:class:`~sqlalchemy.schema.MetaData` instance.
The database connection is presented in the context
of a :class:`.MigrationContext` object, which
provides database connectivity as well as optional
comparison functions to use for datatypes and
server defaults - see the "autogenerate" arguments
at :meth:`.EnvironmentContext.configure`
for details on these.
The return format is a list of "diff" directives,
each representing individual differences::
from alembic.migration import MigrationContext
from alembic.autogenerate import compare_metadata
from sqlalchemy.schema import SchemaItem
from sqlalchemy.types import TypeEngine
from sqlalchemy import (create_engine, MetaData, Column,
Integer, String, Table)
import pprint
engine = create_engine("sqlite://")
engine.execute('''
create table foo (
id integer not null primary key,
old_data varchar,
x integer
)''')
engine.execute('''
create table bar (
data varchar
)''')
metadata = MetaData()
Table('foo', metadata,
Column('id', Integer, primary_key=True),
Column('data', Integer),
Column('x', Integer, nullable=False)
)
Table('bat', metadata,
Column('info', String)
)
mc = MigrationContext.configure(engine.connect())
diff = compare_metadata(mc, metadata)
pprint.pprint(diff, indent=2, width=20)
Output::
[ ( 'add_table',
Table('bat', MetaData(bind=None),
Column('info', String(), table=<bat>), schema=None)),
( 'remove_table',
Table(u'bar', MetaData(bind=None),
Column(u'data', VARCHAR(), table=<bar>), schema=None)),
( 'add_column',
None,
'foo',
Column('data', Integer(), table=<foo>)),
( 'remove_column',
None,
'foo',
Column(u'old_data', VARCHAR(), table=None)),
[ ( 'modify_nullable',
None,
'foo',
u'x',
{ 'existing_server_default': None,
'existing_type': INTEGER()},
True,
False)]]
:param context: a :class:`.MigrationContext`
instance.
:param metadata: a :class:`~sqlalchemy.schema.MetaData`
instance.
"""
autogen_context, connection = _autogen_context(context, None)
diffs = []
object_filters = _get_object_filters(context.opts)
include_schemas = context.opts.get('include_schemas', False)
_produce_net_changes(connection, metadata, diffs, autogen_context,
object_filters, include_schemas)
return diffs
###################################################
# top level
def _produce_migration_diffs(context, template_args,
imports, include_symbol=None,
include_object=None,
include_schemas=False):
opts = context.opts
metadata = opts['target_metadata']
include_schemas = opts.get('include_schemas', include_schemas)
object_filters = _get_object_filters(opts, include_symbol, include_object)
if metadata is None:
raise util.CommandError(
"Can't proceed with --autogenerate option; environment "
"script %s does not provide "
"a MetaData object to the context." % (
context.script.env_py_location
))
autogen_context, connection = _autogen_context(context, imports)
diffs = []
_produce_net_changes(connection, metadata, diffs,
autogen_context, object_filters, include_schemas)
template_args[opts['upgrade_token']] = \
_indent(_produce_upgrade_commands(diffs, autogen_context))
template_args[opts['downgrade_token']] = \
_indent(_produce_downgrade_commands(diffs, autogen_context))
template_args['imports'] = "\n".join(sorted(imports))
def _get_object_filters(context_opts, include_symbol=None, include_object=None):
include_symbol = context_opts.get('include_symbol', include_symbol)
include_object = context_opts.get('include_object', include_object)
object_filters = []
if include_symbol:
def include_symbol_filter(object, name, type_, reflected, compare_to):
if type_ == "table":
return include_symbol(name, object.schema)
else:
return True
object_filters.append(include_symbol_filter)
if include_object:
object_filters.append(include_object)
return object_filters
def _autogen_context(context, imports):
opts = context.opts
connection = context.bind
return {
'imports': imports,
'connection': connection,
'dialect': connection.dialect,
'context': context,
'opts': opts
}, connection
def _indent(text):
text = "### commands auto generated by Alembic - "\
"please adjust! ###\n" + text
text += "\n### end Alembic commands ###"
text = re.compile(r'^', re.M).sub(" ", text).strip()
return text
###################################################
# walk structures
def _produce_net_changes(connection, metadata, diffs, autogen_context,
object_filters=(),
include_schemas=False):
inspector = Inspector.from_engine(connection)
# TODO: not hardcode alembic_version here ?
conn_table_names = set()
default_schema = connection.dialect.default_schema_name
if include_schemas:
schemas = set(inspector.get_schema_names())
# replace default schema name with None
schemas.discard("information_schema")
# replace the "default" schema with None
schemas.add(None)
schemas.discard(default_schema)
else:
schemas = [None]
for s in schemas:
tables = set(inspector.get_table_names(schema=s)).\
difference(['alembic_version'])
conn_table_names.update(zip([s] * len(tables), tables))
metadata_table_names = OrderedSet([(table.schema, table.name)
for table in metadata.sorted_tables])
_compare_tables(conn_table_names, metadata_table_names,
object_filters,
inspector, metadata, diffs, autogen_context)
###################################################
# element comparison
###################################################
# render python
###################################################
# produce command structure
def _produce_upgrade_commands(diffs, autogen_context):
buf = []
for diff in diffs:
buf.append(_invoke_command("upgrade", diff, autogen_context))
if not buf:
buf = ["pass"]
return "\n".join(buf)
def _produce_downgrade_commands(diffs, autogen_context):
buf = []
for diff in reversed(diffs):
buf.append(_invoke_command("downgrade", diff, autogen_context))
if not buf:
buf = ["pass"]
return "\n".join(buf)
def _invoke_command(updown, args, autogen_context):
if isinstance(args, tuple):
return _invoke_adddrop_command(updown, args, autogen_context)
else:
return _invoke_modify_command(updown, args, autogen_context)
def _invoke_adddrop_command(updown, args, autogen_context):
cmd_type = args[0]
adddrop, cmd_type = cmd_type.split("_")
cmd_args = args[1:] + (autogen_context,)
_commands = {
"table": (_drop_table, _add_table),
"column": (_drop_column, _add_column),
"index": (_drop_index, _add_index),
"constraint": (_drop_constraint, _add_constraint),
}
cmd_callables = _commands[cmd_type]
if (
updown == "upgrade" and adddrop == "add"
) or (
updown == "downgrade" and adddrop == "remove"
):
return cmd_callables[1](*cmd_args)
else:
return cmd_callables[0](*cmd_args)
def _invoke_modify_command(updown, args, autogen_context):
sname, tname, cname = args[0][1:4]
kw = {}
_arg_struct = {
"modify_type": ("existing_type", "type_"),
"modify_nullable": ("existing_nullable", "nullable"),
"modify_default": ("existing_server_default", "server_default"),
}
for diff in args:
diff_kw = diff[4]
for arg in ("existing_type", \
"existing_nullable", \
"existing_server_default"):
if arg in diff_kw:
kw.setdefault(arg, diff_kw[arg])
old_kw, new_kw = _arg_struct[diff[0]]
if updown == "upgrade":
kw[new_kw] = diff[-1]
kw[old_kw] = diff[-2]
else:
kw[new_kw] = diff[-2]
kw[old_kw] = diff[-1]
if "nullable" in kw:
kw.pop("existing_nullable", None)
if "server_default" in kw:
kw.pop("existing_server_default", None)
return _modify_col(tname, cname, autogen_context, schema=sname, **kw)