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alembic
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runtime
migration.py
# mypy: allow-untyped-defs, allow-incomplete-defs, allow-untyped-calls # mypy: no-warn-return-any, allow-any-generics 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 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 select from sqlalchemy.engine import Engine from sqlalchemy.engine import url as sqla_url from sqlalchemy.engine.strategies import MockEngineStrategy from typing_extensions import ContextManager 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 import Executable 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", True) 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._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, ) self._version = self.impl.version_table_impl( version_table=version_table, version_table_schema=version_table_schema, version_table_pk=opts.get("version_table_pk", True), ) 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. """ _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, Optional[bool]]]: """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 = [ 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( select(self._version.c.version_num) ) ) 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[Executable, str], execution_options: Optional[Dict[str, Any]] = 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 if TYPE_CHECKING: @property def doc(self) -> Optional[str]: ... @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 else: self.migration_fn = revision.module.downgrade 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) -> Optional[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: Set[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: # for each revision we plan to return, compute its ancestors # (excluding self), and remove those from the final output since # they are already accounted for. ancestors = { r.revision for to_revision in self.to_revisions for r in self.revision_map._get_ancestor_nodes( self.revision_map.get_revisions(to_revision), check=False ) if r.revision != to_revision } return tuple(set(self.to_revisions).difference(ancestors)) def unmerge_branch_idents( self, heads: Set[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.from_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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