8d6ce64cd0
In SQLA 0.9 there is now a native .quote attribute on many objects. Conditionally use this instead of the old method if the attribute exists, to remove deprecation messages (and prepare for when the other way will be fully removed). Change-Id: I3c5fada13e044c1c4102acc0455226ce1524f2e2
314 lines
11 KiB
Python
314 lines
11 KiB
Python
"""
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Extensions to SQLAlchemy for altering existing tables.
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At the moment, this isn't so much based off of ANSI as much as
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things that just happen to work with multiple databases.
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"""
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import StringIO
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import sqlalchemy as sa
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from sqlalchemy.schema import SchemaVisitor
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from sqlalchemy.engine.default import DefaultDialect
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from sqlalchemy.sql import ClauseElement
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from sqlalchemy.schema import (ForeignKeyConstraint,
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PrimaryKeyConstraint,
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CheckConstraint,
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UniqueConstraint,
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Index)
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from migrate import exceptions
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import sqlalchemy.sql.compiler
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from migrate.changeset import constraint
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from migrate.changeset import util
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from sqlalchemy.schema import AddConstraint, DropConstraint
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from sqlalchemy.sql.compiler import DDLCompiler
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SchemaGenerator = SchemaDropper = DDLCompiler
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class AlterTableVisitor(SchemaVisitor):
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"""Common operations for ``ALTER TABLE`` statements."""
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# engine.Compiler looks for .statement
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# when it spawns off a new compiler
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statement = ClauseElement()
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def append(self, s):
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"""Append content to the SchemaIterator's query buffer."""
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self.buffer.write(s)
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def execute(self):
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"""Execute the contents of the SchemaIterator's buffer."""
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try:
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return self.connection.execute(self.buffer.getvalue())
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finally:
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self.buffer.truncate(0)
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def __init__(self, dialect, connection, **kw):
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self.connection = connection
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self.buffer = StringIO.StringIO()
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self.preparer = dialect.identifier_preparer
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self.dialect = dialect
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def traverse_single(self, elem):
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ret = super(AlterTableVisitor, self).traverse_single(elem)
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if ret:
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# adapt to 0.6 which uses a string-returning
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# object
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self.append(" %s" % ret)
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def _to_table(self, param):
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"""Returns the table object for the given param object."""
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if isinstance(param, (sa.Column, sa.Index, sa.schema.Constraint)):
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ret = param.table
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else:
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ret = param
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return ret
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def start_alter_table(self, param):
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"""Returns the start of an ``ALTER TABLE`` SQL-Statement.
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Use the param object to determine the table name and use it
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for building the SQL statement.
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:param param: object to determine the table from
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:type param: :class:`sqlalchemy.Column`, :class:`sqlalchemy.Index`,
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:class:`sqlalchemy.schema.Constraint`, :class:`sqlalchemy.Table`,
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or string (table name)
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"""
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table = self._to_table(param)
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self.append('\nALTER TABLE %s ' % self.preparer.format_table(table))
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return table
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class ANSIColumnGenerator(AlterTableVisitor, SchemaGenerator):
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"""Extends ansisql generator for column creation (alter table add col)"""
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def visit_column(self, column):
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"""Create a column (table already exists).
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:param column: column object
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:type column: :class:`sqlalchemy.Column` instance
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"""
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if column.default is not None:
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self.traverse_single(column.default)
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table = self.start_alter_table(column)
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self.append("ADD ")
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self.append(self.get_column_specification(column))
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for cons in column.constraints:
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self.traverse_single(cons)
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self.execute()
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# ALTER TABLE STATEMENTS
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# add indexes and unique constraints
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if column.index_name:
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Index(column.index_name,column).create()
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elif column.unique_name:
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constraint.UniqueConstraint(column,
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name=column.unique_name).create()
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# SA bounds FK constraints to table, add manually
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for fk in column.foreign_keys:
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self.add_foreignkey(fk.constraint)
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# add primary key constraint if needed
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if column.primary_key_name:
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cons = constraint.PrimaryKeyConstraint(column,
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name=column.primary_key_name)
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cons.create()
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def add_foreignkey(self, fk):
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self.connection.execute(AddConstraint(fk))
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class ANSIColumnDropper(AlterTableVisitor, SchemaDropper):
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"""Extends ANSI SQL dropper for column dropping (``ALTER TABLE
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DROP COLUMN``).
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"""
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def visit_column(self, column):
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"""Drop a column from its table.
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:param column: the column object
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:type column: :class:`sqlalchemy.Column`
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"""
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table = self.start_alter_table(column)
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self.append('DROP COLUMN %s' % self.preparer.format_column(column))
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self.execute()
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class ANSISchemaChanger(AlterTableVisitor, SchemaGenerator):
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"""Manages changes to existing schema elements.
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Note that columns are schema elements; ``ALTER TABLE ADD COLUMN``
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is in SchemaGenerator.
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All items may be renamed. Columns can also have many of their properties -
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type, for example - changed.
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Each function is passed a tuple, containing (object, name); where
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object is a type of object you'd expect for that function
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(ie. table for visit_table) and name is the object's new
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name. NONE means the name is unchanged.
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"""
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def visit_table(self, table):
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"""Rename a table. Other ops aren't supported."""
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self.start_alter_table(table)
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q = util.safe_quote(table)
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self.append("RENAME TO %s" % self.preparer.quote(table.new_name, q))
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self.execute()
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def visit_index(self, index):
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"""Rename an index"""
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if hasattr(self, '_validate_identifier'):
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# SA <= 0.6.3
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self.append("ALTER INDEX %s RENAME TO %s" % (
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self.preparer.quote(
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self._validate_identifier(
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index.name, True), index.quote),
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self.preparer.quote(
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self._validate_identifier(
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index.new_name, True), index.quote)))
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elif hasattr(self, '_index_identifier'):
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# SA >= 0.6.5, < 0.8
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self.append("ALTER INDEX %s RENAME TO %s" % (
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self.preparer.quote(
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self._index_identifier(
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index.name), index.quote),
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self.preparer.quote(
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self._index_identifier(
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index.new_name), index.quote)))
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else:
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# SA >= 0.8
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class NewName(object):
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"""Map obj.name -> obj.new_name"""
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def __init__(self, index):
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self.name = index.new_name
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self._obj = index
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def __getattr__(self, attr):
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if attr == 'name':
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return getattr(self, attr)
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return getattr(self._obj, attr)
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self.append("ALTER INDEX %s RENAME TO %s" % (
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self._prepared_index_name(index),
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self._prepared_index_name(NewName(index))))
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self.execute()
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def visit_column(self, delta):
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"""Rename/change a column."""
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# ALTER COLUMN is implemented as several ALTER statements
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keys = delta.keys()
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if 'type' in keys:
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self._run_subvisit(delta, self._visit_column_type)
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if 'nullable' in keys:
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self._run_subvisit(delta, self._visit_column_nullable)
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if 'server_default' in keys:
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# Skip 'default': only handle server-side defaults, others
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# are managed by the app, not the db.
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self._run_subvisit(delta, self._visit_column_default)
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if 'name' in keys:
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self._run_subvisit(delta, self._visit_column_name, start_alter=False)
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def _run_subvisit(self, delta, func, start_alter=True):
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"""Runs visit method based on what needs to be changed on column"""
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table = self._to_table(delta.table)
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col_name = delta.current_name
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if start_alter:
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self.start_alter_column(table, col_name)
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ret = func(table, delta.result_column, delta)
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self.execute()
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def start_alter_column(self, table, col_name):
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"""Starts ALTER COLUMN"""
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self.start_alter_table(table)
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q = util.safe_quote(table)
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self.append("ALTER COLUMN %s " % self.preparer.quote(col_name, q))
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def _visit_column_nullable(self, table, column, delta):
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nullable = delta['nullable']
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if nullable:
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self.append("DROP NOT NULL")
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else:
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self.append("SET NOT NULL")
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def _visit_column_default(self, table, column, delta):
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default_text = self.get_column_default_string(column)
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if default_text is not None:
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self.append("SET DEFAULT %s" % default_text)
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else:
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self.append("DROP DEFAULT")
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def _visit_column_type(self, table, column, delta):
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type_ = delta['type']
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type_text = str(type_.compile(dialect=self.dialect))
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self.append("TYPE %s" % type_text)
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def _visit_column_name(self, table, column, delta):
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self.start_alter_table(table)
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q = util.safe_quote(table)
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col_name = self.preparer.quote(delta.current_name, q)
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new_name = self.preparer.format_column(delta.result_column)
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self.append('RENAME COLUMN %s TO %s' % (col_name, new_name))
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class ANSIConstraintCommon(AlterTableVisitor):
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"""
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Migrate's constraints require a separate creation function from
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SA's: Migrate's constraints are created independently of a table;
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SA's are created at the same time as the table.
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"""
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def get_constraint_name(self, cons):
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"""Gets a name for the given constraint.
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If the name is already set it will be used otherwise the
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constraint's :meth:`autoname <migrate.changeset.constraint.ConstraintChangeset.autoname>`
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method is used.
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:param cons: constraint object
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"""
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if cons.name is not None:
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ret = cons.name
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else:
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ret = cons.name = cons.autoname()
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return ret
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def visit_migrate_primary_key_constraint(self, *p, **k):
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self._visit_constraint(*p, **k)
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def visit_migrate_foreign_key_constraint(self, *p, **k):
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self._visit_constraint(*p, **k)
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def visit_migrate_check_constraint(self, *p, **k):
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self._visit_constraint(*p, **k)
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def visit_migrate_unique_constraint(self, *p, **k):
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self._visit_constraint(*p, **k)
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class ANSIConstraintGenerator(ANSIConstraintCommon, SchemaGenerator):
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def _visit_constraint(self, constraint):
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constraint.name = self.get_constraint_name(constraint)
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self.append(self.process(AddConstraint(constraint)))
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self.execute()
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class ANSIConstraintDropper(ANSIConstraintCommon, SchemaDropper):
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def _visit_constraint(self, constraint):
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constraint.name = self.get_constraint_name(constraint)
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self.append(self.process(DropConstraint(constraint, cascade=constraint.cascade)))
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self.execute()
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class ANSIDialect(DefaultDialect):
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columngenerator = ANSIColumnGenerator
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columndropper = ANSIColumnDropper
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schemachanger = ANSISchemaChanger
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constraintgenerator = ANSIConstraintGenerator
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constraintdropper = ANSIConstraintDropper
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