from contextlib import contextmanager from sqlalchemy.types import NULLTYPE, Integer from sqlalchemy import schema as sa_schema from . import util, batch from .compat import string_types from .ddl import impl __all__ = ('Operations', 'BatchOperations') try: from sqlalchemy.sql.naming import conv except: conv = None class Operations(object): """Define high level migration operations. Each operation corresponds to some schema migration operation, executed against a particular :class:`.MigrationContext` which in turn represents connectivity to a database, or a file output stream. While :class:`.Operations` is normally configured as part of the :meth:`.EnvironmentContext.run_migrations` method called from an ``env.py`` script, a standalone :class:`.Operations` instance can be made for use cases external to regular Alembic migrations by passing in a :class:`.MigrationContext`:: from alembic.migration import MigrationContext from alembic.operations import Operations conn = myengine.connect() ctx = MigrationContext.configure(conn) op = Operations(ctx) op.alter_column("t", "c", nullable=True) """ def __init__(self, migration_context, impl=None): """Construct a new :class:`.Operations` :param migration_context: a :class:`.MigrationContext` instance. """ self.migration_context = migration_context if impl is None: self.impl = migration_context.impl else: self.impl = impl @classmethod @contextmanager def context(cls, migration_context): from .op import _install_proxy, _remove_proxy op = Operations(migration_context) _install_proxy(op) yield op _remove_proxy() def _primary_key_constraint(self, name, table_name, cols, schema=None): m = self._metadata() columns = [sa_schema.Column(n, NULLTYPE) for n in cols] t1 = sa_schema.Table(table_name, m, *columns, schema=schema) p = sa_schema.PrimaryKeyConstraint(*columns, name=name) t1.append_constraint(p) return p def _foreign_key_constraint(self, name, source, referent, local_cols, remote_cols, onupdate=None, ondelete=None, deferrable=None, source_schema=None, referent_schema=None, initially=None, match=None, **dialect_kw): m = self._metadata() if source == referent: t1_cols = local_cols + remote_cols else: t1_cols = local_cols sa_schema.Table( referent, m, *[sa_schema.Column(n, NULLTYPE) for n in remote_cols], schema=referent_schema) t1 = sa_schema.Table( source, m, *[sa_schema.Column(n, NULLTYPE) for n in t1_cols], schema=source_schema) tname = "%s.%s" % (referent_schema, referent) if referent_schema \ else referent if util.sqla_08: # "match" kw unsupported in 0.7 dialect_kw['match'] = match f = sa_schema.ForeignKeyConstraint(local_cols, ["%s.%s" % (tname, n) for n in remote_cols], name=name, onupdate=onupdate, ondelete=ondelete, deferrable=deferrable, initially=initially, **dialect_kw ) t1.append_constraint(f) return f def _unique_constraint(self, name, source, local_cols, schema=None, **kw): t = sa_schema.Table( source, self._metadata(), *[sa_schema.Column(n, NULLTYPE) for n in local_cols], schema=schema) kw['name'] = name uq = sa_schema.UniqueConstraint(*[t.c[n] for n in local_cols], **kw) # TODO: need event tests to ensure the event # is fired off here t.append_constraint(uq) return uq def _check_constraint(self, name, source, condition, schema=None, **kw): t = sa_schema.Table(source, self._metadata(), sa_schema.Column('x', Integer), schema=schema) ck = sa_schema.CheckConstraint(condition, name=name, **kw) t.append_constraint(ck) return ck def _metadata(self): kw = {} if 'target_metadata' in self.migration_context.opts: mt = self.migration_context.opts['target_metadata'] if hasattr(mt, 'naming_convention'): kw['naming_convention'] = mt.naming_convention return sa_schema.MetaData(**kw) def _table(self, name, *columns, **kw): m = self._metadata() t = sa_schema.Table(name, m, *columns, **kw) for f in t.foreign_keys: self._ensure_table_for_fk(m, f) return t def _column(self, name, type_, **kw): return sa_schema.Column(name, type_, **kw) def _index(self, name, tablename, columns, schema=None, **kw): t = sa_schema.Table( tablename or 'no_table', self._metadata(), schema=schema ) idx = sa_schema.Index( name, *[impl._textual_index_column(t, n) for n in columns], **kw) return idx def _parse_table_key(self, table_key): if '.' in table_key: tokens = table_key.split('.') sname = ".".join(tokens[0:-1]) tname = tokens[-1] else: tname = table_key sname = None return (sname, tname) def _ensure_table_for_fk(self, metadata, fk): """create a placeholder Table object for the referent of a ForeignKey. """ if isinstance(fk._colspec, string_types): table_key, cname = fk._colspec.rsplit('.', 1) sname, tname = self._parse_table_key(table_key) if table_key not in metadata.tables: rel_t = sa_schema.Table(tname, metadata, schema=sname) else: rel_t = metadata.tables[table_key] if cname not in rel_t.c: rel_t.append_column(sa_schema.Column(cname, NULLTYPE)) @contextmanager def batch_alter_table( self, table_name, schema=None, recreate="auto", copy_from=None, table_args=(), table_kwargs=util.immutabledict()): """Invoke a series of per-table migrations in batch. Batch mode allows a series of operations specific to a table to be syntactically grouped together, and allows for alternate modes of table migration, in particular the "recreate" style of migration required by SQLite. "recreate" style is as follows: 1. A new table is created with the new specification, based on the migration directives within the batch, using a temporary name. 2. the data copied from the existing table to the new table. 3. the existing table is dropped. 4. the new table is renamed to the existing table name. The directive by default will only use "recreate" style on the SQLite backend, and only if directives are present which require this form, e.g. anything other than ``add_column()``. The batch operation on other backends will proceed using standard ALTER TABLE operations. The method is used as a context manager, which returns an instance of :class:`.BatchOperations`; this object is the same as :class:`.Operations` except that table names and schema names are omitted. E.g.:: with op.batch_alter_table("some_table") as batch_op: batch_op.add_column(Column('foo', Integer)) batch_op.drop_column('bar') The operations within the context manager are invoked at once when the context is ended. When run against SQLite, if the migrations include operations not supported by SQLite's ALTER TABLE, the entire table will be copied to a new one with the new specification, moving all data across as well. The copy operation by default uses reflection to retrieve the current structure of the table, and therefore :meth:`.batch_alter_table` in this mode requires that the migration is run in "online" mode. The ``copy_from`` parameter may be passed which refers to an existing :class:`.Table` object, which will bypass this reflection step. .. note:: The table copy operation will currently not copy CHECK constraints, and may not copy UNIQUE constraints that are unnamed, as is possible on SQLite. :param table_name: name of table :param schema: optional schema name. :param recreate: under what circumstances the table should be recreated. At its default of ``"auto"``, the SQLite dialect will recreate the table if any operations other than ``add_column()`` are present. Other options include ``"always"`` and ``"never"``. :param copy_from: optional :class:`~sqlalchemy.schema.Table` object that will act as the structure of the table being copied. If omitted, table reflection is used to retrieve the structure of the table. :param table_args: a sequence of additional positional arguments that will be applied to the new :class:`~sqlalchemy.schema.Table` when created, in addition to those copied from the source table. This may be used to provide additional constraints such as CHECK constraints that may not be reflected. :param table_kwargs: a dictionary of additional keyword arguments that will be applied to the new :class:`~sqlalchemy.schema.Table` when created, in addition to those copied from the source table. This may be used to provide for additional table options that may not be reflected. .. versionadded:: 0.7.0 .. note:: batch mode requires SQLAlchemy 0.8 or above. .. seealso:: :ref:`batch_migrations` """ impl = batch.BatchOperationsImpl( self, table_name, schema, recreate, copy_from, table_args, table_kwargs) batch_op = BatchOperations(self.migration_context, impl=impl) yield batch_op impl.flush() def get_context(self): """Return the :class:`.MigrationContext` object that's currently in use. """ return self.migration_context def rename_table(self, old_table_name, new_table_name, schema=None): """Emit an ALTER TABLE to rename a table. :param old_table_name: old name. :param new_table_name: new name. :param schema: Optional schema name to operate within. To control quoting of the schema outside of the default behavior, use the SQLAlchemy construct :class:`~sqlalchemy.sql.elements.quoted_name`. .. versionadded:: 0.7.0 'schema' can now accept a :class:`~sqlalchemy.sql.elements.quoted_name` construct. """ self.impl.rename_table( old_table_name, new_table_name, schema=schema ) @util._with_legacy_names([('name', 'new_column_name')]) def alter_column(self, table_name, column_name, nullable=None, server_default=False, new_column_name=None, type_=None, autoincrement=None, existing_type=None, existing_server_default=False, existing_nullable=None, existing_autoincrement=None, schema=None ): """Issue an "alter column" instruction using the current migration context. Generally, only that aspect of the column which is being changed, i.e. name, type, nullability, default, needs to be specified. Multiple changes can also be specified at once and the backend should "do the right thing", emitting each change either separately or together as the backend allows. MySQL has special requirements here, since MySQL cannot ALTER a column without a full specification. When producing MySQL-compatible migration files, it is recommended that the ``existing_type``, ``existing_server_default``, and ``existing_nullable`` parameters be present, if not being altered. Type changes which are against the SQLAlchemy "schema" types :class:`~sqlalchemy.types.Boolean` and :class:`~sqlalchemy.types.Enum` may also add or drop constraints which accompany those types on backends that don't support them natively. The ``existing_server_default`` argument is used in this case as well to remove a previous constraint. :param table_name: string name of the target table. :param column_name: string name of the target column, as it exists before the operation begins. :param nullable: Optional; specify ``True`` or ``False`` to alter the column's nullability. :param server_default: Optional; specify a string SQL expression, :func:`~sqlalchemy.sql.expression.text`, or :class:`~sqlalchemy.schema.DefaultClause` to indicate an alteration to the column's default value. Set to ``None`` to have the default removed. :param new_column_name: Optional; specify a string name here to indicate the new name within a column rename operation. :param ``type_``: Optional; a :class:`~sqlalchemy.types.TypeEngine` type object to specify a change to the column's type. For SQLAlchemy types that also indicate a constraint (i.e. :class:`~sqlalchemy.types.Boolean`, :class:`~sqlalchemy.types.Enum`), the constraint is also generated. :param autoincrement: set the ``AUTO_INCREMENT`` flag of the column; currently understood by the MySQL dialect. :param existing_type: Optional; a :class:`~sqlalchemy.types.TypeEngine` type object to specify the previous type. This is required for all MySQL column alter operations that don't otherwise specify a new type, as well as for when nullability is being changed on a SQL Server column. It is also used if the type is a so-called SQLlchemy "schema" type which may define a constraint (i.e. :class:`~sqlalchemy.types.Boolean`, :class:`~sqlalchemy.types.Enum`), so that the constraint can be dropped. :param existing_server_default: Optional; The existing default value of the column. Required on MySQL if an existing default is not being changed; else MySQL removes the default. :param existing_nullable: Optional; the existing nullability of the column. Required on MySQL if the existing nullability is not being changed; else MySQL sets this to NULL. :param existing_autoincrement: Optional; the existing autoincrement of the column. Used for MySQL's system of altering a column that specifies ``AUTO_INCREMENT``. :param schema: Optional schema name to operate within. To control quoting of the schema outside of the default behavior, use the SQLAlchemy construct :class:`~sqlalchemy.sql.elements.quoted_name`. .. versionadded:: 0.7.0 'schema' can now accept a :class:`~sqlalchemy.sql.elements.quoted_name` construct. """ compiler = self.impl.dialect.statement_compiler( self.impl.dialect, None ) def _count_constraint(constraint): return not isinstance( constraint, sa_schema.PrimaryKeyConstraint) and \ (not constraint._create_rule or constraint._create_rule(compiler)) if existing_type and type_: t = self._table(table_name, sa_schema.Column(column_name, existing_type), schema=schema ) for constraint in t.constraints: if _count_constraint(constraint): self.impl.drop_constraint(constraint) self.impl.alter_column(table_name, column_name, nullable=nullable, server_default=server_default, name=new_column_name, type_=type_, schema=schema, autoincrement=autoincrement, existing_type=existing_type, existing_server_default=existing_server_default, existing_nullable=existing_nullable, existing_autoincrement=existing_autoincrement ) if type_: t = self._table(table_name, sa_schema.Column(column_name, type_), schema=schema ) for constraint in t.constraints: if _count_constraint(constraint): self.impl.add_constraint(constraint) def f(self, name): """Indicate a string name that has already had a naming convention applied to it. This feature combines with the SQLAlchemy ``naming_convention`` feature to disambiguate constraint names that have already had naming conventions applied to them, versus those that have not. This is necessary in the case that the ``"%(constraint_name)s"`` token is used within a naming convention, so that it can be identified that this particular name should remain fixed. If the :meth:`.Operations.f` is used on a constraint, the naming convention will not take effect:: op.add_column('t', 'x', Boolean(name=op.f('ck_bool_t_x'))) Above, the CHECK constraint generated will have the name ``ck_bool_t_x`` regardless of whether or not a naming convention is in use. Alternatively, if a naming convention is in use, and 'f' is not used, names will be converted along conventions. If the ``target_metadata`` contains the naming convention ``{"ck": "ck_bool_%(table_name)s_%(constraint_name)s"}``, then the output of the following: op.add_column('t', 'x', Boolean(name='x')) will be:: CONSTRAINT ck_bool_t_x CHECK (x in (1, 0))) The function is rendered in the output of autogenerate when a particular constraint name is already converted, for SQLAlchemy version **0.9.4 and greater only**. Even though ``naming_convention`` was introduced in 0.9.2, the string disambiguation service is new as of 0.9.4. .. versionadded:: 0.6.4 """ if conv: return conv(name) else: raise NotImplementedError( "op.f() feature requires SQLAlchemy 0.9.4 or greater.") def add_column(self, table_name, column, schema=None): """Issue an "add column" instruction using the current migration context. e.g.:: from alembic import op from sqlalchemy import Column, String op.add_column('organization', Column('name', String()) ) The provided :class:`~sqlalchemy.schema.Column` object can also specify a :class:`~sqlalchemy.schema.ForeignKey`, referencing a remote table name. Alembic will automatically generate a stub "referenced" table and emit a second ALTER statement in order to add the constraint separately:: from alembic import op from sqlalchemy import Column, INTEGER, ForeignKey op.add_column('organization', Column('account_id', INTEGER, ForeignKey('accounts.id')) ) Note that this statement uses the :class:`~sqlalchemy.schema.Column` construct as is from the SQLAlchemy library. In particular, default values to be created on the database side are specified using the ``server_default`` parameter, and not ``default`` which only specifies Python-side defaults:: from alembic import op from sqlalchemy import Column, TIMESTAMP, func # specify "DEFAULT NOW" along with the column add op.add_column('account', Column('timestamp', TIMESTAMP, server_default=func.now()) ) :param table_name: String name of the parent table. :param column: a :class:`sqlalchemy.schema.Column` object representing the new column. :param schema: Optional schema name to operate within. To control quoting of the schema outside of the default behavior, use the SQLAlchemy construct :class:`~sqlalchemy.sql.elements.quoted_name`. .. versionadded:: 0.7.0 'schema' can now accept a :class:`~sqlalchemy.sql.elements.quoted_name` construct. """ t = self._table(table_name, column, schema=schema) self.impl.add_column( table_name, column, schema=schema ) for constraint in t.constraints: if not isinstance(constraint, sa_schema.PrimaryKeyConstraint): self.impl.add_constraint(constraint) for index in t.indexes: self.impl._exec(sa_schema.CreateIndex(index)) def drop_column(self, table_name, column_name, **kw): """Issue a "drop column" instruction using the current migration context. e.g.:: drop_column('organization', 'account_id') :param table_name: name of table :param column_name: name of column :param schema: Optional schema name to operate within. To control quoting of the schema outside of the default behavior, use the SQLAlchemy construct :class:`~sqlalchemy.sql.elements.quoted_name`. .. versionadded:: 0.7.0 'schema' can now accept a :class:`~sqlalchemy.sql.elements.quoted_name` construct. :param mssql_drop_check: Optional boolean. When ``True``, on Microsoft SQL Server only, first drop the CHECK constraint on the column using a SQL-script-compatible block that selects into a @variable from sys.check_constraints, then exec's a separate DROP CONSTRAINT for that constraint. :param mssql_drop_default: Optional boolean. When ``True``, on Microsoft SQL Server only, first drop the DEFAULT constraint on the column using a SQL-script-compatible block that selects into a @variable from sys.default_constraints, then exec's a separate DROP CONSTRAINT for that default. :param mssql_drop_foreign_key: Optional boolean. When ``True``, on Microsoft SQL Server only, first drop a single FOREIGN KEY constraint on the column using a SQL-script-compatible block that selects into a @variable from sys.foreign_keys/sys.foreign_key_columns, then exec's a separate DROP CONSTRAINT for that default. Only works if the column has exactly one FK constraint which refers to it, at the moment. .. versionadded:: 0.6.2 """ self.impl.drop_column( table_name, self._column(column_name, NULLTYPE), **kw ) def create_primary_key(self, name, table_name, cols, schema=None): """Issue a "create primary key" instruction using the current migration context. e.g.:: from alembic import op op.create_primary_key( "pk_my_table", "my_table", ["id", "version"] ) This internally generates a :class:`~sqlalchemy.schema.Table` object containing the necessary columns, then generates a new :class:`~sqlalchemy.schema.PrimaryKeyConstraint` object which it then associates with the :class:`~sqlalchemy.schema.Table`. Any event listeners associated with this action will be fired off normally. The :class:`~sqlalchemy.schema.AddConstraint` construct is ultimately used to generate the ALTER statement. :param name: Name of the primary key constraint. The name is necessary so that an ALTER statement can be emitted. For setups that use an automated naming scheme such as that described at :ref:`sqla:constraint_naming_conventions` ``name`` here can be ``None``, as the event listener will apply the name to the constraint object when it is associated with the table. :param table_name: String name of the target table. :param cols: a list of string column names to be applied to the primary key constraint. :param schema: Optional schema name to operate within. To control quoting of the schema outside of the default behavior, use the SQLAlchemy construct :class:`~sqlalchemy.sql.elements.quoted_name`. .. versionadded:: 0.7.0 'schema' can now accept a :class:`~sqlalchemy.sql.elements.quoted_name` construct. """ self.impl.add_constraint( self._primary_key_constraint(name, table_name, cols, schema) ) def create_foreign_key(self, name, source, referent, local_cols, remote_cols, onupdate=None, ondelete=None, deferrable=None, initially=None, match=None, source_schema=None, referent_schema=None, **dialect_kw): """Issue a "create foreign key" instruction using the current migration context. e.g.:: from alembic import op op.create_foreign_key( "fk_user_address", "address", "user", ["user_id"], ["id"]) This internally generates a :class:`~sqlalchemy.schema.Table` object containing the necessary columns, then generates a new :class:`~sqlalchemy.schema.ForeignKeyConstraint` object which it then associates with the :class:`~sqlalchemy.schema.Table`. Any event listeners associated with this action will be fired off normally. The :class:`~sqlalchemy.schema.AddConstraint` construct is ultimately used to generate the ALTER statement. :param name: Name of the foreign key constraint. The name is necessary so that an ALTER statement can be emitted. For setups that use an automated naming scheme such as that described at :ref:`sqla:constraint_naming_conventions`, ``name`` here can be ``None``, as the event listener will apply the name to the constraint object when it is associated with the table. :param source: String name of the source table. :param referent: String name of the destination table. :param local_cols: a list of string column names in the source table. :param remote_cols: a list of string column names in the remote table. :param onupdate: Optional string. If set, emit ON UPDATE when issuing DDL for this constraint. Typical values include CASCADE, DELETE and RESTRICT. :param ondelete: Optional string. If set, emit ON DELETE when issuing DDL for this constraint. Typical values include CASCADE, DELETE and RESTRICT. :param deferrable: optional bool. If set, emit DEFERRABLE or NOT DEFERRABLE when issuing DDL for this constraint. :param source_schema: Optional schema name of the source table. :param referent_schema: Optional schema name of the destination table. """ self.impl.add_constraint( self._foreign_key_constraint(name, source, referent, local_cols, remote_cols, onupdate=onupdate, ondelete=ondelete, deferrable=deferrable, source_schema=source_schema, referent_schema=referent_schema, initially=initially, match=match, **dialect_kw) ) def create_unique_constraint(self, name, source, local_cols, schema=None, **kw): """Issue a "create unique constraint" instruction using the current migration context. e.g.:: from alembic import op op.create_unique_constraint("uq_user_name", "user", ["name"]) This internally generates a :class:`~sqlalchemy.schema.Table` object containing the necessary columns, then generates a new :class:`~sqlalchemy.schema.UniqueConstraint` object which it then associates with the :class:`~sqlalchemy.schema.Table`. Any event listeners associated with this action will be fired off normally. The :class:`~sqlalchemy.schema.AddConstraint` construct is ultimately used to generate the ALTER statement. :param name: Name of the unique constraint. The name is necessary so that an ALTER statement can be emitted. For setups that use an automated naming scheme such as that described at :ref:`sqla:constraint_naming_conventions`, ``name`` here can be ``None``, as the event listener will apply the name to the constraint object when it is associated with the table. :param source: String name of the source table. Dotted schema names are supported. :param local_cols: a list of string column names in the source table. :param deferrable: optional bool. If set, emit DEFERRABLE or NOT DEFERRABLE when issuing DDL for this constraint. :param initially: optional string. If set, emit INITIALLY when issuing DDL for this constraint. :param schema: Optional schema name to operate within. To control quoting of the schema outside of the default behavior, use the SQLAlchemy construct :class:`~sqlalchemy.sql.elements.quoted_name`. .. versionadded:: 0.7.0 'schema' can now accept a :class:`~sqlalchemy.sql.elements.quoted_name` construct. """ self.impl.add_constraint( self._unique_constraint(name, source, local_cols, schema=schema, **kw) ) def create_check_constraint(self, name, source, condition, schema=None, **kw): """Issue a "create check constraint" instruction using the current migration context. e.g.:: from alembic import op from sqlalchemy.sql import column, func op.create_check_constraint( "ck_user_name_len", "user", func.len(column('name')) > 5 ) CHECK constraints are usually against a SQL expression, so ad-hoc table metadata is usually needed. The function will convert the given arguments into a :class:`sqlalchemy.schema.CheckConstraint` bound to an anonymous table in order to emit the CREATE statement. :param name: Name of the check constraint. The name is necessary so that an ALTER statement can be emitted. For setups that use an automated naming scheme such as that described at :ref:`sqla:constraint_naming_conventions`, ``name`` here can be ``None``, as the event listener will apply the name to the constraint object when it is associated with the table. :param source: String name of the source table. :param condition: SQL expression that's the condition of the constraint. Can be a string or SQLAlchemy expression language structure. :param deferrable: optional bool. If set, emit DEFERRABLE or NOT DEFERRABLE when issuing DDL for this constraint. :param initially: optional string. If set, emit INITIALLY when issuing DDL for this constraint. :param schema: Optional schema name to operate within. To control quoting of the schema outside of the default behavior, use the SQLAlchemy construct :class:`~sqlalchemy.sql.elements.quoted_name`. .. versionadded:: 0.7.0 'schema' can now accept a :class:`~sqlalchemy.sql.elements.quoted_name` construct. """ self.impl.add_constraint( self._check_constraint( name, source, condition, schema=schema, **kw) ) def create_table(self, name, *columns, **kw): """Issue a "create table" instruction using the current migration context. This directive receives an argument list similar to that of the traditional :class:`sqlalchemy.schema.Table` construct, but without the metadata:: from sqlalchemy import INTEGER, VARCHAR, NVARCHAR, Column from alembic import op op.create_table( 'account', Column('id', INTEGER, primary_key=True), Column('name', VARCHAR(50), nullable=False), Column('description', NVARCHAR(200)), Column('timestamp', TIMESTAMP, server_default=func.now()) ) Note that :meth:`.create_table` accepts :class:`~sqlalchemy.schema.Column` constructs directly from the SQLAlchemy library. In particular, default values to be created on the database side are specified using the ``server_default`` parameter, and not ``default`` which only specifies Python-side defaults:: from alembic import op from sqlalchemy import Column, TIMESTAMP, func # specify "DEFAULT NOW" along with the "timestamp" column op.create_table('account', Column('id', INTEGER, primary_key=True), Column('timestamp', TIMESTAMP, server_default=func.now()) ) The function also returns a newly created :class:`~sqlalchemy.schema.Table` object, corresponding to the table specification given, which is suitable for immediate SQL operations, in particular :meth:`.Operations.bulk_insert`:: from sqlalchemy import INTEGER, VARCHAR, NVARCHAR, Column from alembic import op account_table = op.create_table( 'account', Column('id', INTEGER, primary_key=True), Column('name', VARCHAR(50), nullable=False), Column('description', NVARCHAR(200)), Column('timestamp', TIMESTAMP, server_default=func.now()) ) op.bulk_insert( account_table, [ {"name": "A1", "description": "account 1"}, {"name": "A2", "description": "account 2"}, ] ) .. versionadded:: 0.7.0 :param name: Name of the table :param \*columns: collection of :class:`~sqlalchemy.schema.Column` objects within the table, as well as optional :class:`~sqlalchemy.schema.Constraint` objects and :class:`~.sqlalchemy.schema.Index` objects. :param schema: Optional schema name to operate within. To control quoting of the schema outside of the default behavior, use the SQLAlchemy construct :class:`~sqlalchemy.sql.elements.quoted_name`. .. versionadded:: 0.7.0 'schema' can now accept a :class:`~sqlalchemy.sql.elements.quoted_name` construct. :param \**kw: Other keyword arguments are passed to the underlying :class:`sqlalchemy.schema.Table` object created for the command. :return: the :class:`~sqlalchemy.schema.Table` object corresponding to the parameters given. .. versionadded:: 0.7.0 - the :class:`~sqlalchemy.schema.Table` object is returned. """ table = self._table(name, *columns, **kw) self.impl.create_table(table) return table def drop_table(self, name, **kw): """Issue a "drop table" instruction using the current migration context. e.g.:: drop_table("accounts") :param name: Name of the table :param schema: Optional schema name to operate within. To control quoting of the schema outside of the default behavior, use the SQLAlchemy construct :class:`~sqlalchemy.sql.elements.quoted_name`. .. versionadded:: 0.7.0 'schema' can now accept a :class:`~sqlalchemy.sql.elements.quoted_name` construct. :param \**kw: Other keyword arguments are passed to the underlying :class:`sqlalchemy.schema.Table` object created for the command. """ self.impl.drop_table( self._table(name, **kw) ) def create_index(self, name, table_name, columns, schema=None, unique=False, quote=None, **kw): """Issue a "create index" instruction using the current migration context. e.g.:: from alembic import op op.create_index('ik_test', 't1', ['foo', 'bar']) Functional indexes can be produced by using the :func:`sqlalchemy.sql.expression.text` construct:: from alembic import op from sqlalchemy import text op.create_index('ik_test', 't1', [text('lower(foo)')]) .. versionadded:: 0.6.7 support for making use of the :func:`~sqlalchemy.sql.expression.text` construct in conjunction with :meth:`.Operations.create_index` in order to produce functional expressions within CREATE INDEX. :param name: name of the index. :param table_name: name of the owning table. :param columns: a list consisting of string column names and/or :func:`~sqlalchemy.sql.expression.text` constructs. :param schema: Optional schema name to operate within. To control quoting of the schema outside of the default behavior, use the SQLAlchemy construct :class:`~sqlalchemy.sql.elements.quoted_name`. .. versionadded:: 0.7.0 'schema' can now accept a :class:`~sqlalchemy.sql.elements.quoted_name` construct. :param unique: If True, create a unique index. :param quote: Force quoting of this column's name on or off, corresponding to ``True`` or ``False``. When left at its default of ``None``, the column identifier will be quoted according to whether the name is case sensitive (identifiers with at least one upper case character are treated as case sensitive), or if it's a reserved word. This flag is only needed to force quoting of a reserved word which is not known by the SQLAlchemy dialect. :param \**kw: Additional keyword arguments not mentioned above are dialect specific, and passed in the form ``_``. See the documentation regarding an individual dialect at :ref:`dialect_toplevel` for detail on documented arguments. """ self.impl.create_index( self._index(name, table_name, columns, schema=schema, unique=unique, quote=quote, **kw) ) @util._with_legacy_names([('tablename', 'table_name')]) def drop_index(self, name, table_name=None, schema=None): """Issue a "drop index" instruction using the current migration context. e.g.:: drop_index("accounts") :param name: name of the index. :param table_name: name of the owning table. Some backends such as Microsoft SQL Server require this. :param schema: Optional schema name to operate within. To control quoting of the schema outside of the default behavior, use the SQLAlchemy construct :class:`~sqlalchemy.sql.elements.quoted_name`. .. versionadded:: 0.7.0 'schema' can now accept a :class:`~sqlalchemy.sql.elements.quoted_name` construct. """ # need a dummy column name here since SQLAlchemy # 0.7.6 and further raises on Index with no columns self.impl.drop_index( self._index(name, table_name, ['x'], schema=schema) ) @util._with_legacy_names([("type", "type_")]) def drop_constraint(self, name, table_name, type_=None, schema=None): """Drop a constraint of the given name, typically via DROP CONSTRAINT. :param name: name of the constraint. :param table_name: table name. :param ``type_``: optional, required on MySQL. can be 'foreignkey', 'primary', 'unique', or 'check'. :param schema: Optional schema name to operate within. To control quoting of the schema outside of the default behavior, use the SQLAlchemy construct :class:`~sqlalchemy.sql.elements.quoted_name`. .. versionadded:: 0.7.0 'schema' can now accept a :class:`~sqlalchemy.sql.elements.quoted_name` construct. """ t = self._table(table_name, schema=schema) types = { 'foreignkey': lambda name: sa_schema.ForeignKeyConstraint( [], [], name=name), 'primary': sa_schema.PrimaryKeyConstraint, 'unique': sa_schema.UniqueConstraint, 'check': lambda name: sa_schema.CheckConstraint("", name=name), None: sa_schema.Constraint } try: const = types[type_] except KeyError: raise TypeError("'type' can be one of %s" % ", ".join(sorted(repr(x) for x in types))) const = const(name=name) t.append_constraint(const) self.impl.drop_constraint(const) def bulk_insert(self, table, rows, multiinsert=True): """Issue a "bulk insert" operation using the current migration context. This provides a means of representing an INSERT of multiple rows which works equally well in the context of executing on a live connection as well as that of generating a SQL script. In the case of a SQL script, the values are rendered inline into the statement. e.g.:: from alembic import op from datetime import date from sqlalchemy.sql import table, column from sqlalchemy import String, Integer, Date # Create an ad-hoc table to use for the insert statement. accounts_table = table('account', column('id', Integer), column('name', String), column('create_date', Date) ) op.bulk_insert(accounts_table, [ {'id':1, 'name':'John Smith', 'create_date':date(2010, 10, 5)}, {'id':2, 'name':'Ed Williams', 'create_date':date(2007, 5, 27)}, {'id':3, 'name':'Wendy Jones', 'create_date':date(2008, 8, 15)}, ] ) When using --sql mode, some datatypes may not render inline automatically, such as dates and other special types. When this issue is present, :meth:`.Operations.inline_literal` may be used:: op.bulk_insert(accounts_table, [ {'id':1, 'name':'John Smith', 'create_date':op.inline_literal("2010-10-05")}, {'id':2, 'name':'Ed Williams', 'create_date':op.inline_literal("2007-05-27")}, {'id':3, 'name':'Wendy Jones', 'create_date':op.inline_literal("2008-08-15")}, ], multiinsert=False ) When using :meth:`.Operations.inline_literal` in conjunction with :meth:`.Operations.bulk_insert`, in order for the statement to work in "online" (e.g. non --sql) mode, the :paramref:`~.Operations.bulk_insert.multiinsert` flag should be set to ``False``, which will have the effect of individual INSERT statements being emitted to the database, each with a distinct VALUES clause, so that the "inline" values can still be rendered, rather than attempting to pass the values as bound parameters. .. versionadded:: 0.6.4 :meth:`.Operations.inline_literal` can now be used with :meth:`.Operations.bulk_insert`, and the :paramref:`~.Operations.bulk_insert.multiinsert` flag has been added to assist in this usage when running in "online" mode. :param table: a table object which represents the target of the INSERT. :param rows: a list of dictionaries indicating rows. :param multiinsert: when at its default of True and --sql mode is not enabled, the INSERT statement will be executed using "executemany()" style, where all elements in the list of dictionaries are passed as bound parameters in a single list. Setting this to False results in individual INSERT statements being emitted per parameter set, and is needed in those cases where non-literal values are present in the parameter sets. .. versionadded:: 0.6.4 """ self.impl.bulk_insert(table, rows, multiinsert=multiinsert) def inline_literal(self, value, type_=None): """Produce an 'inline literal' expression, suitable for using in an INSERT, UPDATE, or DELETE statement. When using Alembic in "offline" mode, CRUD operations aren't compatible with SQLAlchemy's default behavior surrounding literal values, which is that they are converted into bound values and passed separately into the ``execute()`` method of the DBAPI cursor. An offline SQL script needs to have these rendered inline. While it should always be noted that inline literal values are an **enormous** security hole in an application that handles untrusted input, a schema migration is not run in this context, so literals are safe to render inline, with the caveat that advanced types like dates may not be supported directly by SQLAlchemy. See :meth:`.execute` for an example usage of :meth:`.inline_literal`. :param value: The value to render. Strings, integers, and simple numerics should be supported. Other types like boolean, dates, etc. may or may not be supported yet by various backends. :param ``type_``: optional - a :class:`sqlalchemy.types.TypeEngine` subclass stating the type of this value. In SQLAlchemy expressions, this is usually derived automatically from the Python type of the value itself, as well as based on the context in which the value is used. """ return impl._literal_bindparam(None, value, type_=type_) def execute(self, sql, execution_options=None): """Execute the given SQL using the current migration context. In a SQL script context, the statement is emitted directly to the output stream. There is *no* return result, however, as this function is oriented towards generating a change script that can run in "offline" mode. For full interaction with a connected database, use the "bind" available from the context:: from alembic import op connection = op.get_bind() Also note that any parameterized statement here *will not work* in offline mode - INSERT, UPDATE and DELETE statements which refer to literal values would need to render inline expressions. For simple use cases, the :meth:`.inline_literal` function can be used for **rudimentary** quoting of string values. For "bulk" inserts, consider using :meth:`.bulk_insert`. For example, to emit an UPDATE statement which is equally compatible with both online and offline mode:: from sqlalchemy.sql import table, column from sqlalchemy import String from alembic import op account = table('account', column('name', String) ) op.execute( account.update().\\ where(account.c.name==op.inline_literal('account 1')).\\ values({'name':op.inline_literal('account 2')}) ) Note above we also used the SQLAlchemy :func:`sqlalchemy.sql.expression.table` and :func:`sqlalchemy.sql.expression.column` constructs to make a brief, ad-hoc table construct just for our UPDATE statement. A full :class:`~sqlalchemy.schema.Table` construct of course works perfectly fine as well, though note it's a recommended practice to at least ensure the definition of a table is self-contained within the migration script, rather than imported from a module that may break compatibility with older migrations. :param sql: Any legal SQLAlchemy expression, including: * a string * a :func:`sqlalchemy.sql.expression.text` construct. * a :func:`sqlalchemy.sql.expression.insert` construct. * a :func:`sqlalchemy.sql.expression.update`, :func:`sqlalchemy.sql.expression.insert`, or :func:`sqlalchemy.sql.expression.delete` construct. * Pretty much anything that's "executable" as described in :ref:`sqlexpression_toplevel`. :param execution_options: Optional dictionary of execution options, will be passed to :meth:`sqlalchemy.engine.Connection.execution_options`. """ self.migration_context.impl.execute( sql, execution_options=execution_options) def get_bind(self): """Return the current 'bind'. Under normal circumstances, this is the :class:`~sqlalchemy.engine.Connection` currently being used to emit SQL to the database. In a SQL script context, this value is ``None``. [TODO: verify this] """ return self.migration_context.impl.bind class BatchOperations(Operations): """Modifies the interface :class:`.Operations` for batch mode. This basically omits the ``table_name`` and ``schema`` parameters from associated methods, as these are a given when running under batch mode. .. seealso:: :meth:`.Operations.batch_alter_table` """ def _noop(self, operation): raise NotImplementedError( "The %s method does not apply to a batch table alter operation." % operation) def add_column(self, column): """Issue an "add column" instruction using the current batch migration context. .. seealso:: :meth:`.Operations.add_column` """ return super(BatchOperations, self).add_column( self.impl.table_name, column, schema=self.impl.schema) def alter_column(self, column_name, **kw): """Issue an "alter column" instruction using the current batch migration context. .. seealso:: :meth:`.Operations.add_column` """ kw['schema'] = self.impl.schema return super(BatchOperations, self).alter_column( self.impl.table_name, column_name, **kw) def drop_column(self, column_name): """Issue a "drop column" instruction using the current batch migration context. .. seealso:: :meth:`.Operations.drop_column` """ return super(BatchOperations, self).drop_column( self.impl.table_name, column_name, schema=self.impl.schema) def create_primary_key(self, name, cols): """Issue a "create priamry key" instruction using the current batch migration context. The batch form of this call omits the ``table_name`` and ``schema`` arguments from the call. .. seealso:: :meth:`.Operations.create_primary_key` """ raise NotImplementedError("not yet implemented") def create_foreign_key( self, name, referent, local_cols, remote_cols, **kw): """Issue a "create foreign key" instruction using the current batch migration context. The batch form of this call omits the ``source`` and ``source_schema`` arguments from the call. e.g.:: with batch_alter_table("address") as batch_op: batch_op.create_foreign_key( "fk_user_address", "user", ["user_id"], ["id"]) .. seealso:: :meth:`.Operations.create_foreign_key` """ return super(BatchOperations, self).create_foreign_key( name, self.impl.table_name, referent, local_cols, remote_cols, schema=self.impl.schema) def create_unique_constraint(self, name, local_cols, **kw): """Issue a "create unique constraint" instruction using the current batch migration context. The batch form of this call omits the ``source`` and ``schema`` arguments from the call. .. seealso:: :meth:`.Operations.create_unique_constraint` """ kw['schema'] = self.impl.schema return super(BatchOperations, self).create_unique_constraint( name, self.impl.table_name, local_cols, **kw) def create_check_constraint(self, name, condition, **kw): """Issue a "create check constraint" instruction using the current batch migration context. The batch form of this call omits the ``source`` and ``schema`` arguments from the call. .. seealso:: :meth:`.Operations.create_check_constraint` """ raise NotImplementedError("not yet implemented") def drop_constraint(self, name, type_=None): """Issue a "drop constraint" instruction using the current batch migration context. The batch form of this call omits the ``table_name`` and ``schema`` arguments from the call. .. seealso:: :meth:`.Operations.drop_constraint` """ return super(BatchOperations, self).drop_constraint( name, self.impl.table_name, type_=type_, schema=self.impl.schema) def create_index(self, name, columns, **kw): """Issue a "create index" instruction using the current batch migration context.""" kw['schema'] = self.impl.schema return super(BatchOperations, self).create_index( name, self.impl.table_name, columns, **kw) def drop_index(self, name, **kw): """Issue a "drop index" instruction using the current batch migration context.""" kw['schema'] = self.impl.schema return super(BatchOperations, self).drop_index( name, self.impl.table_name, **kw)