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hc_python
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alembic
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autogenerate
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api.py
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from __future__ import annotations import contextlib from typing import Any from typing import Dict from typing import Iterator from typing import List from typing import Optional from typing import Sequence from typing import Set from typing import TYPE_CHECKING from typing import Union from sqlalchemy import inspect from . import compare from . import render from .. import util from ..operations import ops from ..util import sqla_compat """Provide the 'autogenerate' feature which can produce migration operations automatically.""" if TYPE_CHECKING: from sqlalchemy.engine import Connection from sqlalchemy.engine import Dialect from sqlalchemy.engine import Inspector from sqlalchemy.sql.schema import MetaData from sqlalchemy.sql.schema import SchemaItem from sqlalchemy.sql.schema import Table from ..config import Config from ..operations.ops import DowngradeOps from ..operations.ops import MigrationScript from ..operations.ops import UpgradeOps from ..runtime.environment import NameFilterParentNames from ..runtime.environment import NameFilterType from ..runtime.environment import ProcessRevisionDirectiveFn from ..runtime.environment import RenderItemFn from ..runtime.migration import MigrationContext from ..script.base import Script from ..script.base import ScriptDirectory from ..script.revision import _GetRevArg def compare_metadata(context: MigrationContext, metadata: MetaData) -> Any: """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 import ( create_engine, MetaData, Column, Integer, String, Table, text, ) import pprint engine = create_engine("sqlite://") with engine.begin() as conn: conn.execute( text( ''' create table foo ( id integer not null primary key, old_data varchar, x integer ) ''' ) ) conn.execute(text("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(), Column("info", String(), table=<bat>), schema=None, ), ), ( "remove_table", Table( "bar", MetaData(), Column("data", VARCHAR(), table=<bar>), schema=None, ), ), ( "add_column", None, "foo", Column("data", Integer(), table=<foo>), ), [ ( "modify_nullable", None, "foo", "x", { "existing_comment": None, "existing_server_default": False, "existing_type": INTEGER(), }, True, False, ) ], ( "remove_column", None, "foo", Column("old_data", VARCHAR(), table=<foo>), ), ] :param context: a :class:`.MigrationContext` instance. :param metadata: a :class:`~sqlalchemy.schema.MetaData` instance. .. seealso:: :func:`.produce_migrations` - produces a :class:`.MigrationScript` structure based on metadata comparison. """ migration_script = produce_migrations(context, metadata) assert migration_script.upgrade_ops is not None return migration_script.upgrade_ops.as_diffs() def produce_migrations( context: MigrationContext, metadata: MetaData ) -> MigrationScript: """Produce a :class:`.MigrationScript` structure based on schema comparison. This function does essentially what :func:`.compare_metadata` does, but then runs the resulting list of diffs to produce the full :class:`.MigrationScript` object. For an example of what this looks like, see the example in :ref:`customizing_revision`. .. seealso:: :func:`.compare_metadata` - returns more fundamental "diff" data from comparing a schema. """ autogen_context = AutogenContext(context, metadata=metadata) migration_script = ops.MigrationScript( rev_id=None, upgrade_ops=ops.UpgradeOps([]), downgrade_ops=ops.DowngradeOps([]), ) compare._populate_migration_script(autogen_context, migration_script) return migration_script def render_python_code( up_or_down_op: Union[UpgradeOps, DowngradeOps], sqlalchemy_module_prefix: str = "sa.", alembic_module_prefix: str = "op.", render_as_batch: bool = False, imports: Sequence[str] = (), render_item: Optional[RenderItemFn] = None, migration_context: Optional[MigrationContext] = None, user_module_prefix: Optional[str] = None, ) -> str: """Render Python code given an :class:`.UpgradeOps` or :class:`.DowngradeOps` object. This is a convenience function that can be used to test the autogenerate output of a user-defined :class:`.MigrationScript` structure. :param up_or_down_op: :class:`.UpgradeOps` or :class:`.DowngradeOps` object :param sqlalchemy_module_prefix: module prefix for SQLAlchemy objects :param alembic_module_prefix: module prefix for Alembic constructs :param render_as_batch: use "batch operations" style for rendering :param imports: sequence of import symbols to add :param render_item: callable to render items :param migration_context: optional :class:`.MigrationContext` :param user_module_prefix: optional string prefix for user-defined types .. versionadded:: 1.11.0 """ opts = { "sqlalchemy_module_prefix": sqlalchemy_module_prefix, "alembic_module_prefix": alembic_module_prefix, "render_item": render_item, "render_as_batch": render_as_batch, "user_module_prefix": user_module_prefix, } if migration_context is None: from ..runtime.migration import MigrationContext from sqlalchemy.engine.default import DefaultDialect migration_context = MigrationContext.configure( dialect=DefaultDialect() ) autogen_context = AutogenContext(migration_context, opts=opts) autogen_context.imports = set(imports) return render._indent( render._render_cmd_body(up_or_down_op, autogen_context) ) def _render_migration_diffs( context: MigrationContext, template_args: Dict[Any, Any] ) -> None: """legacy, used by test_autogen_composition at the moment""" autogen_context = AutogenContext(context) upgrade_ops = ops.UpgradeOps([]) compare._produce_net_changes(autogen_context, upgrade_ops) migration_script = ops.MigrationScript( rev_id=None, upgrade_ops=upgrade_ops, downgrade_ops=upgrade_ops.reverse(), ) render._render_python_into_templatevars( autogen_context, migration_script, template_args ) class AutogenContext: """Maintains configuration and state that's specific to an autogenerate operation.""" metadata: Optional[MetaData] = None """The :class:`~sqlalchemy.schema.MetaData` object representing the destination. This object is the one that is passed within ``env.py`` to the :paramref:`.EnvironmentContext.configure.target_metadata` parameter. It represents the structure of :class:`.Table` and other objects as stated in the current database model, and represents the destination structure for the database being examined. While the :class:`~sqlalchemy.schema.MetaData` object is primarily known as a collection of :class:`~sqlalchemy.schema.Table` objects, it also has an :attr:`~sqlalchemy.schema.MetaData.info` dictionary that may be used by end-user schemes to store additional schema-level objects that are to be compared in custom autogeneration schemes. """ connection: Optional[Connection] = None """The :class:`~sqlalchemy.engine.base.Connection` object currently connected to the database backend being compared. This is obtained from the :attr:`.MigrationContext.bind` and is ultimately set up in the ``env.py`` script. """ dialect: Optional[Dialect] = None """The :class:`~sqlalchemy.engine.Dialect` object currently in use. This is normally obtained from the :attr:`~sqlalchemy.engine.base.Connection.dialect` attribute. """ imports: Set[str] = None # type: ignore[assignment] """A ``set()`` which contains string Python import directives. The directives are to be rendered into the ``${imports}`` section of a script template. The set is normally empty and can be modified within hooks such as the :paramref:`.EnvironmentContext.configure.render_item` hook. .. seealso:: :ref:`autogen_render_types` """ migration_context: MigrationContext = None # type: ignore[assignment] """The :class:`.MigrationContext` established by the ``env.py`` script.""" def __init__( self, migration_context: MigrationContext, metadata: Optional[MetaData] = None, opts: Optional[Dict[str, Any]] = None, autogenerate: bool = True, ) -> None: if ( autogenerate and migration_context is not None and migration_context.as_sql ): raise util.CommandError( "autogenerate can't use as_sql=True as it prevents querying " "the database for schema information" ) if opts is None: opts = migration_context.opts self.metadata = metadata = ( opts.get("target_metadata", None) if metadata is None else metadata ) if ( autogenerate and metadata is None and migration_context is not None and migration_context.script is not None ): raise util.CommandError( "Can't proceed with --autogenerate option; environment " "script %s does not provide " "a MetaData object or sequence of objects to the context." % (migration_context.script.env_py_location) ) include_object = opts.get("include_object", None) include_name = opts.get("include_name", None) object_filters = [] name_filters = [] if include_object: object_filters.append(include_object) if include_name: name_filters.append(include_name) self._object_filters = object_filters self._name_filters = name_filters self.migration_context = migration_context if self.migration_context is not None: self.connection = self.migration_context.bind self.dialect = self.migration_context.dialect self.imports = set() self.opts: Dict[str, Any] = opts self._has_batch: bool = False @util.memoized_property def inspector(self) -> Inspector: if self.connection is None: raise TypeError( "can't return inspector as this " "AutogenContext has no database connection" ) return inspect(self.connection) @contextlib.contextmanager def _within_batch(self) -> Iterator[None]: self._has_batch = True yield self._has_batch = False def run_name_filters( self, name: Optional[str], type_: NameFilterType, parent_names: NameFilterParentNames, ) -> bool: """Run the context's name filters and return True if the targets should be part of the autogenerate operation. This method should be run for every kind of name encountered within the reflection side of an autogenerate operation, giving the environment the chance to filter what names should be reflected as database objects. The filters here are produced directly via the :paramref:`.EnvironmentContext.configure.include_name` parameter. """ if "schema_name" in parent_names: if type_ == "table": table_name = name else: table_name = parent_names.get("table_name", None) if table_name: schema_name = parent_names["schema_name"] if schema_name: parent_names["schema_qualified_table_name"] = "%s.%s" % ( schema_name, table_name, ) else: parent_names["schema_qualified_table_name"] = table_name for fn in self._name_filters: if not fn(name, type_, parent_names): return False else: return True def run_object_filters( self, object_: SchemaItem, name: sqla_compat._ConstraintName, type_: NameFilterType, reflected: bool, compare_to: Optional[SchemaItem], ) -> bool: """Run the context's object filters and return True if the targets should be part of the autogenerate operation. This method should be run for every kind of object encountered within an autogenerate operation, giving the environment the chance to filter what objects should be included in the comparison. The filters here are produced directly via the :paramref:`.EnvironmentContext.configure.include_object` parameter. """ for fn in self._object_filters: if not fn(object_, name, type_, reflected, compare_to): return False else: return True run_filters = run_object_filters @util.memoized_property def sorted_tables(self) -> List[Table]: """Return an aggregate of the :attr:`.MetaData.sorted_tables` collection(s). For a sequence of :class:`.MetaData` objects, this concatenates the :attr:`.MetaData.sorted_tables` collection for each individual :class:`.MetaData` in the order of the sequence. It does **not** collate the sorted tables collections. """ result = [] for m in util.to_list(self.metadata): result.extend(m.sorted_tables) return result @util.memoized_property def table_key_to_table(self) -> Dict[str, Table]: """Return an aggregate of the :attr:`.MetaData.tables` dictionaries. The :attr:`.MetaData.tables` collection is a dictionary of table key to :class:`.Table`; this method aggregates the dictionary across multiple :class:`.MetaData` objects into one dictionary. Duplicate table keys are **not** supported; if two :class:`.MetaData` objects contain the same table key, an exception is raised. """ result: Dict[str, Table] = {} for m in util.to_list(self.metadata): intersect = set(result).intersection(set(m.tables)) if intersect: raise ValueError( "Duplicate table keys across multiple " "MetaData objects: %s" % (", ".join('"%s"' % key for key in sorted(intersect))) ) result.update(m.tables) return result class RevisionContext: """Maintains configuration and state that's specific to a revision file generation operation.""" generated_revisions: List[MigrationScript] process_revision_directives: Optional[ProcessRevisionDirectiveFn] def __init__( self, config: Config, script_directory: ScriptDirectory, command_args: Dict[str, Any], process_revision_directives: Optional[ ProcessRevisionDirectiveFn ] = None, ) -> None: self.config = config self.script_directory = script_directory self.command_args = command_args self.process_revision_directives = process_revision_directives self.template_args = { "config": config # Let templates use config for # e.g. multiple databases } self.generated_revisions = [self._default_revision()] def _to_script( self, migration_script: MigrationScript ) -> Optional[Script]: template_args: Dict[str, Any] = self.template_args.copy() if getattr(migration_script, "_needs_render", False): autogen_context = self._last_autogen_context # clear out existing imports if we are doing multiple # renders autogen_context.imports = set() if migration_script.imports: autogen_context.imports.update(migration_script.imports) render._render_python_into_templatevars( autogen_context, migration_script, template_args ) assert migration_script.rev_id is not None return self.script_directory.generate_revision( migration_script.rev_id, migration_script.message, refresh=True, head=migration_script.head, splice=migration_script.splice, branch_labels=migration_script.branch_label, version_path=migration_script.version_path, depends_on=migration_script.depends_on, **template_args, ) def run_autogenerate( self, rev: _GetRevArg, migration_context: MigrationContext ) -> None: self._run_environment(rev, migration_context, True) def run_no_autogenerate( self, rev: _GetRevArg, migration_context: MigrationContext ) -> None: self._run_environment(rev, migration_context, False) def _run_environment( self, rev: _GetRevArg, migration_context: MigrationContext, autogenerate: bool, ) -> None: if autogenerate: if self.command_args["sql"]: raise util.CommandError( "Using --sql with --autogenerate does not make any sense" ) if set(self.script_directory.get_revisions(rev)) != set( self.script_directory.get_revisions("heads") ): raise util.CommandError("Target database is not up to date.") upgrade_token = migration_context.opts["upgrade_token"] downgrade_token = migration_context.opts["downgrade_token"] migration_script = self.generated_revisions[-1] if not getattr(migration_script, "_needs_render", False): migration_script.upgrade_ops_list[-1].upgrade_token = upgrade_token migration_script.downgrade_ops_list[-1].downgrade_token = ( downgrade_token ) migration_script._needs_render = True else: migration_script._upgrade_ops.append( ops.UpgradeOps([], upgrade_token=upgrade_token) ) migration_script._downgrade_ops.append( ops.DowngradeOps([], downgrade_token=downgrade_token) ) autogen_context = AutogenContext( migration_context, autogenerate=autogenerate ) self._last_autogen_context: AutogenContext = autogen_context if autogenerate: compare._populate_migration_script( autogen_context, migration_script ) if self.process_revision_directives: self.process_revision_directives( migration_context, rev, self.generated_revisions ) hook = migration_context.opts["process_revision_directives"] if hook: hook(migration_context, rev, self.generated_revisions) for migration_script in self.generated_revisions: migration_script._needs_render = True def _default_revision(self) -> MigrationScript: command_args: Dict[str, Any] = self.command_args op = ops.MigrationScript( rev_id=command_args["rev_id"] or util.rev_id(), message=command_args["message"], upgrade_ops=ops.UpgradeOps([]), downgrade_ops=ops.DowngradeOps([]), head=command_args["head"], splice=command_args["splice"], branch_label=command_args["branch_label"], version_path=command_args["version_path"], depends_on=command_args["depends_on"], ) return op def generate_scripts(self) -> Iterator[Optional[Script]]: for generated_revision in self.generated_revisions: yield self._to_script(generated_revision)