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from __future__ import annotations
from contextlib import contextmanager
from contextlib import nullcontext
import logging
import sys
from typing import Any
from typing import Callable
from typing import cast
from typing import Collection
from typing import ContextManager
from typing import Dict
from typing import Iterable
from typing import Iterator
from typing import List
from typing import Optional
from typing import Set
from typing import Tuple
from typing import TYPE_CHECKING
from typing import Union
from sqlalchemy import Column
from sqlalchemy import literal_column
from sqlalchemy import MetaData
from sqlalchemy import PrimaryKeyConstraint
from sqlalchemy import String
from sqlalchemy import Table
from sqlalchemy.engine import Engine
from sqlalchemy.engine import url as sqla_url
from sqlalchemy.engine.strategies import MockEngineStrategy
from .. import ddl
from .. import util
from ..util import sqla_compat
from ..util.compat import EncodedIO
if TYPE_CHECKING:
from sqlalchemy.engine import Dialect
from sqlalchemy.engine import URL
from sqlalchemy.engine.base import Connection
from sqlalchemy.engine.base import Transaction
from sqlalchemy.engine.mock import MockConnection
from sqlalchemy.sql.elements import ClauseElement
from .environment import EnvironmentContext
from ..config import Config
from ..script.base import Script
from ..script.base import ScriptDirectory
from ..script.revision import _RevisionOrBase
from ..script.revision import Revision
from ..script.revision import RevisionMap
log = logging.getLogger(__name__)
class _ProxyTransaction:
def __init__(self, migration_context: MigrationContext) -> None:
self.migration_context = migration_context
@property
def _proxied_transaction(self) -> Optional[Transaction]:
return self.migration_context._transaction
def rollback(self) -> None:
t = self._proxied_transaction
assert t is not None
t.rollback()
self.migration_context._transaction = None
def commit(self) -> None:
t = self._proxied_transaction
assert t is not None
t.commit()
self.migration_context._transaction = None
def __enter__(self) -> _ProxyTransaction:
return self
def __exit__(self, type_: Any, value: Any, traceback: Any) -> None:
if self._proxied_transaction is not None:
self._proxied_transaction.__exit__(type_, value, traceback)
self.migration_context._transaction = None
class MigrationContext:
"""Represent the database state made available to a migration
script.
:class:`.MigrationContext` is the front end to an actual
database connection, or alternatively a string output
stream given a particular database dialect,
from an Alembic perspective.
When inside the ``env.py`` script, the :class:`.MigrationContext`
is available via the
:meth:`.EnvironmentContext.get_context` method,
which is available at ``alembic.context``::
# from within env.py script
from alembic import context
migration_context = context.get_context()
For usage outside of an ``env.py`` script, such as for
utility routines that want to check the current version
in the database, the :meth:`.MigrationContext.configure`
method to create new :class:`.MigrationContext` objects.
For example, to get at the current revision in the
database using :meth:`.MigrationContext.get_current_revision`::
# in any application, outside of an env.py script
from alembic.migration import MigrationContext
from sqlalchemy import create_engine
engine = create_engine("postgresql://mydatabase")
conn = engine.connect()
context = MigrationContext.configure(conn)
current_rev = context.get_current_revision()
The above context can also be used to produce
Alembic migration operations with an :class:`.Operations`
instance::
# in any application, outside of the normal Alembic environment
from alembic.operations import Operations
op = Operations(context)
op.alter_column("mytable", "somecolumn", nullable=True)
"""
def __init__(
self,
dialect: Dialect,
connection: Optional[Connection],
opts: Dict[str, Any],
environment_context: Optional[EnvironmentContext] = None,
) -> None:
self.environment_context = environment_context
self.opts = opts
self.dialect = dialect
self.script: Optional[ScriptDirectory] = opts.get("script")
as_sql: bool = opts.get("as_sql", False)
transactional_ddl = opts.get("transactional_ddl")
self._transaction_per_migration = opts.get(
"transaction_per_migration", False
)
self.on_version_apply_callbacks = opts.get("on_version_apply", ())
self._transaction: Optional[Transaction] = None
if as_sql:
self.connection = cast(
Optional["Connection"], self._stdout_connection(connection)
)
assert self.connection is not None
self._in_external_transaction = False
else:
self.connection = connection
self._in_external_transaction = (
sqla_compat._get_connection_in_transaction(connection)
)
self._migrations_fn: Optional[
Callable[..., Iterable[RevisionStep]]
] = opts.get("fn")
self.as_sql = as_sql
self.purge = opts.get("purge", False)
if "output_encoding" in opts:
self.output_buffer = EncodedIO(
opts.get("output_buffer")
or sys.stdout, # type:ignore[arg-type]
opts["output_encoding"],
)
else:
self.output_buffer = opts.get("output_buffer", sys.stdout)
self._user_compare_type = opts.get("compare_type", False)
self._user_compare_server_default = opts.get(
"compare_server_default", False
)
self.version_table = version_table = opts.get(
"version_table", "alembic_version"
)
self.version_table_schema = version_table_schema = opts.get(
"version_table_schema", None
)
self._version = Table(
version_table,
MetaData(),
Column("version_num", String(32), nullable=False),
schema=version_table_schema,
)
if opts.get("version_table_pk", True):
self._version.append_constraint(
PrimaryKeyConstraint(
"version_num", name="%s_pkc" % version_table
)
)
self._start_from_rev: Optional[str] = opts.get("starting_rev")
self.impl = ddl.DefaultImpl.get_by_dialect(dialect)(
dialect,
self.connection,
self.as_sql,
transactional_ddl,
self.output_buffer,
opts,
)
log.info("Context impl %s.", self.impl.__class__.__name__)
if self.as_sql:
log.info("Generating static SQL")
log.info(
"Will assume %s DDL.",
"transactional"
if self.impl.transactional_ddl
else "non-transactional",
)
@classmethod
def configure(
cls,
connection: Optional[Connection] = None,
url: Optional[Union[str, URL]] = None,
dialect_name: Optional[str] = None,
dialect: Optional[Dialect] = None,
environment_context: Optional[EnvironmentContext] = None,
dialect_opts: Optional[Dict[str, str]] = None,
opts: Optional[Any] = None,
) -> MigrationContext:
"""Create a new :class:`.MigrationContext`.
This is a factory method usually called
by :meth:`.EnvironmentContext.configure`.
:param connection: a :class:`~sqlalchemy.engine.Connection`
to use for SQL execution in "online" mode. When present,
is also used to determine the type of dialect in use.
:param url: a string database url, or a
:class:`sqlalchemy.engine.url.URL` object.
The type of dialect to be used will be derived from this if
``connection`` is not passed.
:param dialect_name: string name of a dialect, such as
"postgresql", "mssql", etc. The type of dialect to be used will be
derived from this if ``connection`` and ``url`` are not passed.
:param opts: dictionary of options. Most other options
accepted by :meth:`.EnvironmentContext.configure` are passed via
this dictionary.
"""
if opts is None:
opts = {}
if dialect_opts is None:
dialect_opts = {}
if connection:
if isinstance(connection, Engine):
raise util.CommandError(
"'connection' argument to configure() is expected "
"to be a sqlalchemy.engine.Connection instance, "
"got %r" % connection,
)
dialect = connection.dialect
elif url:
url_obj = sqla_url.make_url(url)
dialect = url_obj.get_dialect()(**dialect_opts)
elif dialect_name:
url_obj = sqla_url.make_url("%s://" % dialect_name)
dialect = url_obj.get_dialect()(**dialect_opts)
elif not dialect:
raise Exception("Connection, url, or dialect_name is required.")
assert dialect is not None
return MigrationContext(dialect, connection, opts, environment_context)
@contextmanager
def autocommit_block(self) -> Iterator[None]:
"""Enter an "autocommit" block, for databases that support AUTOCOMMIT
isolation levels.
This special directive is intended to support the occasional database
DDL or system operation that specifically has to be run outside of
any kind of transaction block. The PostgreSQL database platform
is the most common target for this style of operation, as many
of its DDL operations must be run outside of transaction blocks, even
though the database overall supports transactional DDL.
The method is used as a context manager within a migration script, by
calling on :meth:`.Operations.get_context` to retrieve the
:class:`.MigrationContext`, then invoking
:meth:`.MigrationContext.autocommit_block` using the ``with:``
statement::
def upgrade():
with op.get_context().autocommit_block():
op.execute("ALTER TYPE mood ADD VALUE 'soso'")
Above, a PostgreSQL "ALTER TYPE..ADD VALUE" directive is emitted,
which must be run outside of a transaction block at the database level.
The :meth:`.MigrationContext.autocommit_block` method makes use of the
SQLAlchemy ``AUTOCOMMIT`` isolation level setting, which against the
psycogp2 DBAPI corresponds to the ``connection.autocommit`` setting,
to ensure that the database driver is not inside of a DBAPI level
transaction block.
.. warning::
As is necessary, **the database transaction preceding the block is
unconditionally committed**. This means that the run of migrations
preceding the operation will be committed, before the overall
migration operation is complete.
It is recommended that when an application includes migrations with
"autocommit" blocks, that
:paramref:`.EnvironmentContext.transaction_per_migration` be used
so that the calling environment is tuned to expect short per-file
migrations whether or not one of them has an autocommit block.
.. versionadded:: 1.2.0
"""
_in_connection_transaction = self._in_connection_transaction()
if self.impl.transactional_ddl and self.as_sql:
self.impl.emit_commit()
elif _in_connection_transaction:
assert self._transaction is not None
self._transaction.commit()
self._transaction = None
if not self.as_sql:
assert self.connection is not None
current_level = self.connection.get_isolation_level()
base_connection = self.connection
# in 1.3 and 1.4 non-future mode, the connection gets switched
# out. we can use the base connection with the new mode
# except that it will not know it's in "autocommit" and will
# emit deprecation warnings when an autocommit action takes
# place.
self.connection = (
self.impl.connection
) = base_connection.execution_options(isolation_level="AUTOCOMMIT")
# sqlalchemy future mode will "autobegin" in any case, so take
# control of that "transaction" here
fake_trans: Optional[Transaction] = self.connection.begin()
else:
fake_trans = None
try:
yield
finally:
if not self.as_sql:
assert self.connection is not None
if fake_trans is not None:
fake_trans.commit()
self.connection.execution_options(
isolation_level=current_level
)
self.connection = self.impl.connection = base_connection
if self.impl.transactional_ddl and self.as_sql:
self.impl.emit_begin()
elif _in_connection_transaction:
assert self.connection is not None
self._transaction = self.connection.begin()
def begin_transaction(
self, _per_migration: bool = False
) -> Union[_ProxyTransaction, ContextManager[None]]:
"""Begin a logical transaction for migration operations.
This method is used within an ``env.py`` script to demarcate where
the outer "transaction" for a series of migrations begins. Example::
def run_migrations_online():
connectable = create_engine(...)
with connectable.connect() as connection:
context.configure(
connection=connection, target_metadata=target_metadata
)
with context.begin_transaction():
context.run_migrations()
Above, :meth:`.MigrationContext.begin_transaction` is used to demarcate
where the outer logical transaction occurs around the
:meth:`.MigrationContext.run_migrations` operation.
A "Logical" transaction means that the operation may or may not
correspond to a real database transaction. If the target database
supports transactional DDL (or
:paramref:`.EnvironmentContext.configure.transactional_ddl` is true),
the :paramref:`.EnvironmentContext.configure.transaction_per_migration`
flag is not set, and the migration is against a real database
connection (as opposed to using "offline" ``--sql`` mode), a real
transaction will be started. If ``--sql`` mode is in effect, the
operation would instead correspond to a string such as "BEGIN" being
emitted to the string output.
The returned object is a Python context manager that should only be
used in the context of a ``with:`` statement as indicated above.
The object has no other guaranteed API features present.
.. seealso::
:meth:`.MigrationContext.autocommit_block`
"""
if self._in_external_transaction:
return nullcontext()
if self.impl.transactional_ddl:
transaction_now = _per_migration == self._transaction_per_migration
else:
transaction_now = _per_migration is True
if not transaction_now:
return nullcontext()
elif not self.impl.transactional_ddl:
assert _per_migration
if self.as_sql:
return nullcontext()
else:
# track our own notion of a "transaction block", which must be
# committed when complete. Don't rely upon whether or not the
# SQLAlchemy connection reports as "in transaction"; this
# because SQLAlchemy future connection features autobegin
# behavior, so it may already be in a transaction from our
# emitting of queries like "has_version_table", etc. While we
# could track these operations as well, that leaves open the
# possibility of new operations or other things happening in
# the user environment that still may be triggering
# "autobegin".
in_transaction = self._transaction is not None
if in_transaction:
return nullcontext()
else:
assert self.connection is not None
self._transaction = (
sqla_compat._safe_begin_connection_transaction(
self.connection
)
)
return _ProxyTransaction(self)
elif self.as_sql:
@contextmanager
def begin_commit():
self.impl.emit_begin()
yield
self.impl.emit_commit()
return begin_commit()
else:
assert self.connection is not None
self._transaction = sqla_compat._safe_begin_connection_transaction(
self.connection
)
return _ProxyTransaction(self)
def get_current_revision(self) -> Optional[str]:
"""Return the current revision, usually that which is present
in the ``alembic_version`` table in the database.
This method intends to be used only for a migration stream that
does not contain unmerged branches in the target database;
if there are multiple branches present, an exception is raised.
The :meth:`.MigrationContext.get_current_heads` should be preferred
over this method going forward in order to be compatible with
branch migration support.
If this :class:`.MigrationContext` was configured in "offline"
mode, that is with ``as_sql=True``, the ``starting_rev``
parameter is returned instead, if any.
"""
heads = self.get_current_heads()
if len(heads) == 0:
return None
elif len(heads) > 1:
raise util.CommandError(
"Version table '%s' has more than one head present; "
"please use get_current_heads()" % self.version_table
)
else:
return heads[0]
def get_current_heads(self) -> Tuple[str, ...]:
"""Return a tuple of the current 'head versions' that are represented
in the target database.
For a migration stream without branches, this will be a single
value, synonymous with that of
:meth:`.MigrationContext.get_current_revision`. However when multiple
unmerged branches exist within the target database, the returned tuple
will contain a value for each head.
If this :class:`.MigrationContext` was configured in "offline"
mode, that is with ``as_sql=True``, the ``starting_rev``
parameter is returned in a one-length tuple.
If no version table is present, or if there are no revisions
present, an empty tuple is returned.
"""
if self.as_sql:
start_from_rev: Any = self._start_from_rev
if start_from_rev == "base":
start_from_rev = None
elif start_from_rev is not None and self.script:
start_from_rev = [
cast("Script", self.script.get_revision(sfr)).revision
for sfr in util.to_list(start_from_rev)
if sfr not in (None, "base")
]
return util.to_tuple(start_from_rev, default=())
else:
if self._start_from_rev:
raise util.CommandError(
"Can't specify current_rev to context "
"when using a database connection"
)
if not self._has_version_table():
return ()
assert self.connection is not None
return tuple(
row[0] for row in self.connection.execute(self._version.select())
)
def _ensure_version_table(self, purge: bool = False) -> None:
with sqla_compat._ensure_scope_for_ddl(self.connection):
assert self.connection is not None
self._version.create(self.connection, checkfirst=True)
if purge:
assert self.connection is not None
self.connection.execute(self._version.delete())
def _has_version_table(self) -> bool:
assert self.connection is not None
return sqla_compat._connectable_has_table(
self.connection, self.version_table, self.version_table_schema
)
def stamp(self, script_directory: ScriptDirectory, revision: str) -> None:
"""Stamp the version table with a specific revision.
This method calculates those branches to which the given revision
can apply, and updates those branches as though they were migrated
towards that revision (either up or down). If no current branches
include the revision, it is added as a new branch head.
"""
heads = self.get_current_heads()
if not self.as_sql and not heads:
self._ensure_version_table()
head_maintainer = HeadMaintainer(self, heads)
for step in script_directory._stamp_revs(revision, heads):
head_maintainer.update_to_step(step)
def run_migrations(self, **kw: Any) -> None:
r"""Run the migration scripts established for this
:class:`.MigrationContext`, if any.
The commands in :mod:`alembic.command` will set up a function
that is ultimately passed to the :class:`.MigrationContext`
as the ``fn`` argument. This function represents the "work"
that will be done when :meth:`.MigrationContext.run_migrations`
is called, typically from within the ``env.py`` script of the
migration environment. The "work function" then provides an iterable
of version callables and other version information which
in the case of the ``upgrade`` or ``downgrade`` commands are the
list of version scripts to invoke. Other commands yield nothing,
in the case that a command wants to run some other operation
against the database such as the ``current`` or ``stamp`` commands.
:param \**kw: keyword arguments here will be passed to each
migration callable, that is the ``upgrade()`` or ``downgrade()``
method within revision scripts.
"""
self.impl.start_migrations()
heads: Tuple[str, ...]
if self.purge:
if self.as_sql:
raise util.CommandError("Can't use --purge with --sql mode")
self._ensure_version_table(purge=True)
heads = ()
else:
heads = self.get_current_heads()
dont_mutate = self.opts.get("dont_mutate", False)
if not self.as_sql and not heads and not dont_mutate:
self._ensure_version_table()
head_maintainer = HeadMaintainer(self, heads)
assert self._migrations_fn is not None
for step in self._migrations_fn(heads, self):
with self.begin_transaction(_per_migration=True):
if self.as_sql and not head_maintainer.heads:
# for offline mode, include a CREATE TABLE from
# the base
assert self.connection is not None
self._version.create(self.connection)
log.info("Running %s", step)
if self.as_sql:
self.impl.static_output(
"-- Running %s" % (step.short_log,)
)
step.migration_fn(**kw)
# previously, we wouldn't stamp per migration
# if we were in a transaction, however given the more
# complex model that involves any number of inserts
# and row-targeted updates and deletes, it's simpler for now
# just to run the operations on every version
head_maintainer.update_to_step(step)
for callback in self.on_version_apply_callbacks:
callback(
ctx=self,
step=step.info,
heads=set(head_maintainer.heads),
run_args=kw,
)
if self.as_sql and not head_maintainer.heads:
assert self.connection is not None
self._version.drop(self.connection)
def _in_connection_transaction(self) -> bool:
try:
meth = self.connection.in_transaction # type:ignore[union-attr]
except AttributeError:
return False
else:
return meth()
def execute(
self,
sql: Union[ClauseElement, str],
execution_options: Optional[dict] = None,
) -> None:
"""Execute a SQL construct or string statement.
The underlying execution mechanics are used, that is
if this is "offline mode" the SQL is written to the
output buffer, otherwise the SQL is emitted on
the current SQLAlchemy connection.
"""
self.impl._exec(sql, execution_options)
def _stdout_connection(
self, connection: Optional[Connection]
) -> MockConnection:
def dump(construct, *multiparams, **params):
self.impl._exec(construct)
return MockEngineStrategy.MockConnection(self.dialect, dump)
@property
def bind(self) -> Optional[Connection]:
"""Return the current "bind".
In online mode, this is an instance of
:class:`sqlalchemy.engine.Connection`, and is suitable
for ad-hoc execution of any kind of usage described
in SQLAlchemy Core documentation as well as
for usage with the :meth:`sqlalchemy.schema.Table.create`
and :meth:`sqlalchemy.schema.MetaData.create_all` methods
of :class:`~sqlalchemy.schema.Table`,
:class:`~sqlalchemy.schema.MetaData`.
Note that when "standard output" mode is enabled,
this bind will be a "mock" connection handler that cannot
return results and is only appropriate for a very limited
subset of commands.
"""
return self.connection
@property
def config(self) -> Optional[Config]:
"""Return the :class:`.Config` used by the current environment,
if any."""
if self.environment_context:
return self.environment_context.config
else:
return None
def _compare_type(
self, inspector_column: Column[Any], metadata_column: Column
) -> bool:
if self._user_compare_type is False:
return False
if callable(self._user_compare_type):
user_value = self._user_compare_type(
self,
inspector_column,
metadata_column,
inspector_column.type,
metadata_column.type,
)
if user_value is not None:
return user_value
return self.impl.compare_type(inspector_column, metadata_column)
def _compare_server_default(
self,
inspector_column: Column[Any],
metadata_column: Column[Any],
rendered_metadata_default: Optional[str],
rendered_column_default: Optional[str],
) -> bool:
if self._user_compare_server_default is False:
return False
if callable(self._user_compare_server_default):
user_value = self._user_compare_server_default(
self,
inspector_column,
metadata_column,
rendered_column_default,
metadata_column.server_default,
rendered_metadata_default,
)
if user_value is not None:
return user_value
return self.impl.compare_server_default(
inspector_column,
metadata_column,
rendered_metadata_default,
rendered_column_default,
)
class HeadMaintainer:
def __init__(self, context: MigrationContext, heads: Any) -> None:
self.context = context
self.heads = set(heads)
def _insert_version(self, version: str) -> None:
assert version not in self.heads
self.heads.add(version)
self.context.impl._exec(
self.context._version.insert().values(
version_num=literal_column("'%s'" % version)
)
)
def _delete_version(self, version: str) -> None:
self.heads.remove(version)
ret = self.context.impl._exec(
self.context._version.delete().where(
self.context._version.c.version_num
== literal_column("'%s'" % version)
)
)
if (
not self.context.as_sql
and self.context.dialect.supports_sane_rowcount
and ret is not None
and ret.rowcount != 1
):
raise util.CommandError(
"Online migration expected to match one "
"row when deleting '%s' in '%s'; "
"%d found"
% (version, self.context.version_table, ret.rowcount)
)
def _update_version(self, from_: str, to_: str) -> None:
assert to_ not in self.heads
self.heads.remove(from_)
self.heads.add(to_)
ret = self.context.impl._exec(
self.context._version.update()
.values(version_num=literal_column("'%s'" % to_))
.where(
self.context._version.c.version_num
== literal_column("'%s'" % from_)
)
)
if (
not self.context.as_sql
and self.context.dialect.supports_sane_rowcount
and ret is not None
and ret.rowcount != 1
):
raise util.CommandError(
"Online migration expected to match one "
"row when updating '%s' to '%s' in '%s'; "
"%d found"
% (from_, to_, self.context.version_table, ret.rowcount)
)
def update_to_step(self, step: Union[RevisionStep, StampStep]) -> None:
if step.should_delete_branch(self.heads):
vers = step.delete_version_num
log.debug("branch delete %s", vers)
self._delete_version(vers)
elif step.should_create_branch(self.heads):
vers = step.insert_version_num
log.debug("new branch insert %s", vers)
self._insert_version(vers)
elif step.should_merge_branches(self.heads):
# delete revs, update from rev, update to rev
(
delete_revs,
update_from_rev,
update_to_rev,
) = step.merge_branch_idents(self.heads)
log.debug(
"merge, delete %s, update %s to %s",
delete_revs,
update_from_rev,
update_to_rev,
)
for delrev in delete_revs:
self._delete_version(delrev)
self._update_version(update_from_rev, update_to_rev)
elif step.should_unmerge_branches(self.heads):
(
update_from_rev,
update_to_rev,
insert_revs,
) = step.unmerge_branch_idents(self.heads)
log.debug(
"unmerge, insert %s, update %s to %s",
insert_revs,
update_from_rev,
update_to_rev,
)
for insrev in insert_revs:
self._insert_version(insrev)
self._update_version(update_from_rev, update_to_rev)
else:
from_, to_ = step.update_version_num(self.heads)
log.debug("update %s to %s", from_, to_)
self._update_version(from_, to_)
class MigrationInfo:
"""Exposes information about a migration step to a callback listener.
The :class:`.MigrationInfo` object is available exclusively for the
benefit of the :paramref:`.EnvironmentContext.on_version_apply`
callback hook.
"""
is_upgrade: bool
"""True/False: indicates whether this operation ascends or descends the
version tree."""
is_stamp: bool
"""True/False: indicates whether this operation is a stamp (i.e. whether
it results in any actual database operations)."""
up_revision_id: Optional[str]
"""Version string corresponding to :attr:`.Revision.revision`.
In the case of a stamp operation, it is advised to use the
:attr:`.MigrationInfo.up_revision_ids` tuple as a stamp operation can
make a single movement from one or more branches down to a single
branchpoint, in which case there will be multiple "up" revisions.
.. seealso::
:attr:`.MigrationInfo.up_revision_ids`
"""
up_revision_ids: Tuple[str, ...]
"""Tuple of version strings corresponding to :attr:`.Revision.revision`.
In the majority of cases, this tuple will be a single value, synonymous
with the scalar value of :attr:`.MigrationInfo.up_revision_id`.
It can be multiple revision identifiers only in the case of an
``alembic stamp`` operation which is moving downwards from multiple
branches down to their common branch point.
"""
down_revision_ids: Tuple[str, ...]
"""Tuple of strings representing the base revisions of this migration step.
If empty, this represents a root revision; otherwise, the first item
corresponds to :attr:`.Revision.down_revision`, and the rest are inferred
from dependencies.
"""
revision_map: RevisionMap
"""The revision map inside of which this operation occurs."""
def __init__(
self,
revision_map: RevisionMap,
is_upgrade: bool,
is_stamp: bool,
up_revisions: Union[str, Tuple[str, ...]],
down_revisions: Union[str, Tuple[str, ...]],
) -> None:
self.revision_map = revision_map
self.is_upgrade = is_upgrade
self.is_stamp = is_stamp
self.up_revision_ids = util.to_tuple(up_revisions, default=())
if self.up_revision_ids:
self.up_revision_id = self.up_revision_ids[0]
else:
# this should never be the case with
# "upgrade", "downgrade", or "stamp" as we are always
# measuring movement in terms of at least one upgrade version
self.up_revision_id = None
self.down_revision_ids = util.to_tuple(down_revisions, default=())
@property
def is_migration(self) -> bool:
"""True/False: indicates whether this operation is a migration.
At present this is true if and only the migration is not a stamp.
If other operation types are added in the future, both this attribute
and :attr:`~.MigrationInfo.is_stamp` will be false.
"""
return not self.is_stamp
@property
def source_revision_ids(self) -> Tuple[str, ...]:
"""Active revisions before this migration step is applied."""
return (
self.down_revision_ids if self.is_upgrade else self.up_revision_ids
)
@property
def destination_revision_ids(self) -> Tuple[str, ...]:
"""Active revisions after this migration step is applied."""
return (
self.up_revision_ids if self.is_upgrade else self.down_revision_ids
)
@property
def up_revision(self) -> Optional[Revision]:
"""Get :attr:`~.MigrationInfo.up_revision_id` as
a :class:`.Revision`.
"""
return self.revision_map.get_revision(self.up_revision_id)
@property
def up_revisions(self) -> Tuple[Optional[_RevisionOrBase], ...]:
"""Get :attr:`~.MigrationInfo.up_revision_ids` as a
:class:`.Revision`."""
return self.revision_map.get_revisions(self.up_revision_ids)
@property
def down_revisions(self) -> Tuple[Optional[_RevisionOrBase], ...]:
"""Get :attr:`~.MigrationInfo.down_revision_ids` as a tuple of
:class:`Revisions <.Revision>`."""
return self.revision_map.get_revisions(self.down_revision_ids)
@property
def source_revisions(self) -> Tuple[Optional[_RevisionOrBase], ...]:
"""Get :attr:`~MigrationInfo.source_revision_ids` as a tuple of
:class:`Revisions <.Revision>`."""
return self.revision_map.get_revisions(self.source_revision_ids)
@property
def destination_revisions(self) -> Tuple[Optional[_RevisionOrBase], ...]:
"""Get :attr:`~MigrationInfo.destination_revision_ids` as a tuple of
:class:`Revisions <.Revision>`."""
return self.revision_map.get_revisions(self.destination_revision_ids)
class MigrationStep:
from_revisions_no_deps: Tuple[str, ...]
to_revisions_no_deps: Tuple[str, ...]
is_upgrade: bool
migration_fn: Any
@property
def name(self) -> str:
return self.migration_fn.__name__
@classmethod
def upgrade_from_script(
cls, revision_map: RevisionMap, script: Script
) -> RevisionStep:
return RevisionStep(revision_map, script, True)
@classmethod
def downgrade_from_script(
cls, revision_map: RevisionMap, script: Script
) -> RevisionStep:
return RevisionStep(revision_map, script, False)
@property
def is_downgrade(self) -> bool:
return not self.is_upgrade
@property
def short_log(self) -> str:
return "%s %s -> %s" % (
self.name,
util.format_as_comma(self.from_revisions_no_deps),
util.format_as_comma(self.to_revisions_no_deps),
)
def __str__(self):
if self.doc:
return "%s %s -> %s, %s" % (
self.name,
util.format_as_comma(self.from_revisions_no_deps),
util.format_as_comma(self.to_revisions_no_deps),
self.doc,
)
else:
return self.short_log
class RevisionStep(MigrationStep):
def __init__(
self, revision_map: RevisionMap, revision: Script, is_upgrade: bool
) -> None:
self.revision_map = revision_map
self.revision = revision
self.is_upgrade = is_upgrade
if is_upgrade:
self.migration_fn = (
revision.module.upgrade # type:ignore[attr-defined]
)
else:
self.migration_fn = (
revision.module.downgrade # type:ignore[attr-defined]
)
def __repr__(self):
return "RevisionStep(%r, is_upgrade=%r)" % (
self.revision.revision,
self.is_upgrade,
)
def __eq__(self, other: object) -> bool:
return (
isinstance(other, RevisionStep)
and other.revision == self.revision
and self.is_upgrade == other.is_upgrade
)
@property
def doc(self) -> str:
return self.revision.doc
@property
def from_revisions(self) -> Tuple[str, ...]:
if self.is_upgrade:
return self.revision._normalized_down_revisions
else:
return (self.revision.revision,)
@property
def from_revisions_no_deps( # type:ignore[override]
self,
) -> Tuple[str, ...]:
if self.is_upgrade:
return self.revision._versioned_down_revisions
else:
return (self.revision.revision,)
@property
def to_revisions(self) -> Tuple[str, ...]:
if self.is_upgrade:
return (self.revision.revision,)
else:
return self.revision._normalized_down_revisions
@property
def to_revisions_no_deps( # type:ignore[override]
self,
) -> Tuple[str, ...]:
if self.is_upgrade:
return (self.revision.revision,)
else:
return self.revision._versioned_down_revisions
@property
def _has_scalar_down_revision(self) -> bool:
return len(self.revision._normalized_down_revisions) == 1
def should_delete_branch(self, heads: Set[str]) -> bool:
"""A delete is when we are a. in a downgrade and b.
we are going to the "base" or we are going to a version that
is implied as a dependency on another version that is remaining.
"""
if not self.is_downgrade:
return False
if self.revision.revision not in heads:
return False
downrevs = self.revision._normalized_down_revisions
if not downrevs:
# is a base
return True
else:
# determine what the ultimate "to_revisions" for an
# unmerge would be. If there are none, then we're a delete.
to_revisions = self._unmerge_to_revisions(heads)
return not to_revisions
def merge_branch_idents(
self, heads: Set[str]
) -> Tuple[List[str], str, str]:
other_heads = set(heads).difference(self.from_revisions)
if other_heads:
ancestors = {
r.revision
for r in self.revision_map._get_ancestor_nodes(
self.revision_map.get_revisions(other_heads), check=False
)
}
from_revisions = list(
set(self.from_revisions).difference(ancestors)
)
else:
from_revisions = list(self.from_revisions)
return (
# delete revs, update from rev, update to rev
list(from_revisions[0:-1]),
from_revisions[-1],
self.to_revisions[0],
)
def _unmerge_to_revisions(self, heads: Collection[str]) -> Tuple[str, ...]:
other_heads = set(heads).difference([self.revision.revision])
if other_heads:
ancestors = {
r.revision
for r in self.revision_map._get_ancestor_nodes(
self.revision_map.get_revisions(other_heads), check=False
)
}
return tuple(set(self.to_revisions).difference(ancestors))
else:
return self.to_revisions
def unmerge_branch_idents(
self, heads: Collection[str]
) -> Tuple[str, str, Tuple[str, ...]]:
to_revisions = self._unmerge_to_revisions(heads)
return (
# update from rev, update to rev, insert revs
self.from_revisions[0],
to_revisions[-1],
to_revisions[0:-1],
)
def should_create_branch(self, heads: Set[str]) -> bool:
if not self.is_upgrade:
return False
downrevs = self.revision._normalized_down_revisions
if not downrevs:
# is a base
return True
else:
# none of our downrevs are present, so...
# we have to insert our version. This is true whether
# or not there is only one downrev, or multiple (in the latter
# case, we're a merge point.)
if not heads.intersection(downrevs):
return True
else:
return False
def should_merge_branches(self, heads: Set[str]) -> bool:
if not self.is_upgrade:
return False
downrevs = self.revision._normalized_down_revisions
if len(downrevs) > 1 and len(heads.intersection(downrevs)) > 1:
return True
return False
def should_unmerge_branches(self, heads: Set[str]) -> bool:
if not self.is_downgrade:
return False
downrevs = self.revision._normalized_down_revisions
if self.revision.revision in heads and len(downrevs) > 1:
return True
return False
def update_version_num(self, heads: Set[str]) -> Tuple[str, str]:
if not self._has_scalar_down_revision:
downrev = heads.intersection(
self.revision._normalized_down_revisions
)
assert (
len(downrev) == 1
), "Can't do an UPDATE because downrevision is ambiguous"
down_revision = list(downrev)[0]
else:
down_revision = self.revision._normalized_down_revisions[0]
if self.is_upgrade:
return down_revision, self.revision.revision
else:
return self.revision.revision, down_revision
@property
def delete_version_num(self) -> str:
return self.revision.revision
@property
def insert_version_num(self) -> str:
return self.revision.revision
@property
def info(self) -> MigrationInfo:
return MigrationInfo(
revision_map=self.revision_map,
up_revisions=self.revision.revision,
down_revisions=self.revision._normalized_down_revisions,
is_upgrade=self.is_upgrade,
is_stamp=False,
)
class StampStep(MigrationStep):
def __init__(
self,
from_: Optional[Union[str, Collection[str]]],
to_: Optional[Union[str, Collection[str]]],
is_upgrade: bool,
branch_move: bool,
revision_map: Optional[RevisionMap] = None,
) -> None:
self.from_: Tuple[str, ...] = util.to_tuple(from_, default=())
self.to_: Tuple[str, ...] = util.to_tuple(to_, default=())
self.is_upgrade = is_upgrade
self.branch_move = branch_move
self.migration_fn = self.stamp_revision
self.revision_map = revision_map
doc: Optional[str] = None
def stamp_revision(self, **kw: Any) -> None:
return None
def __eq__(self, other):
return (
isinstance(other, StampStep)
and other.from_revisions == self.revisions
and other.to_revisions == self.to_revisions
and other.branch_move == self.branch_move
and self.is_upgrade == other.is_upgrade
)
@property
def from_revisions(self):
return self.from_
@property
def to_revisions(self) -> Tuple[str, ...]:
return self.to_
@property
def from_revisions_no_deps( # type:ignore[override]
self,
) -> Tuple[str, ...]:
return self.from_
@property
def to_revisions_no_deps( # type:ignore[override]
self,
) -> Tuple[str, ...]:
return self.to_
@property
def delete_version_num(self) -> str:
assert len(self.from_) == 1
return self.from_[0]
@property
def insert_version_num(self) -> str:
assert len(self.to_) == 1
return self.to_[0]
def update_version_num(self, heads: Set[str]) -> Tuple[str, str]:
assert len(self.from_) == 1
assert len(self.to_) == 1
return self.from_[0], self.to_[0]
def merge_branch_idents(
self, heads: Union[Set[str], List[str]]
) -> Union[Tuple[List[Any], str, str], Tuple[List[str], str, str]]:
return (
# delete revs, update from rev, update to rev
list(self.from_[0:-1]),
self.from_[-1],
self.to_[0],
)
def unmerge_branch_idents(
self, heads: Set[str]
) -> Tuple[str, str, List[str]]:
return (
# update from rev, update to rev, insert revs
self.from_[0],
self.to_[-1],
list(self.to_[0:-1]),
)
def should_delete_branch(self, heads: Set[str]) -> bool:
# TODO: we probably need to look for self.to_ inside of heads,
# in a similar manner as should_create_branch, however we have
# no tests for this yet (stamp downgrades w/ branches)
return self.is_downgrade and self.branch_move
def should_create_branch(self, heads: Set[str]) -> Union[Set[str], bool]:
return (
self.is_upgrade
and (self.branch_move or set(self.from_).difference(heads))
and set(self.to_).difference(heads)
)
def should_merge_branches(self, heads: Set[str]) -> bool:
return len(self.from_) > 1
def should_unmerge_branches(self, heads: Set[str]) -> bool:
return len(self.to_) > 1
@property
def info(self) -> MigrationInfo:
up, down = (
(self.to_, self.from_)
if self.is_upgrade
else (self.from_, self.to_)
)
assert self.revision_map is not None
return MigrationInfo(
revision_map=self.revision_map,
up_revisions=up,
down_revisions=down,
is_upgrade=self.is_upgrade,
is_stamp=True,
)
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