x/sqlalchemy-migrate
Code Issues Proposed changes

make migrate.schema.ansisql PEP8 clean and add some sphinx docstrings

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jan.dittberner 2009-01-25 12:51:49 +00:00
parent 6e22528e6f
commit 4806e2c9e1
1 changed files with 151 additions and 106 deletions
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103
migrate/changeset/ansisql.py
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@ -1,43 +1,60 @@
"""
Module :mod:`migrate.changeset.ansisql`
---------------------------------------
Extensions to SQLAlchemy for altering existing tables.
At the moment, this isn't so much based off of ANSI as much as things that just
happen to work with multiple databases.
At the moment, this isn't so much based off of ANSI as much as
things that just happen to work with multiple databases.
"""
import sqlalchemy as sa
from sqlalchemy.engine.base import Connection, Dialect
from sqlalchemy.sql.compiler import SchemaGenerator
from sqlalchemy.schema import ForeignKeyConstraint
from migrate.changeset import constraint, exceptions
SchemaIterator = sa.engine.SchemaIterator
class RawAlterTableVisitor(object):
"""Common operations for 'alter table' statements"""
"""Common operations for ``ALTER TABLE`` statements."""
def _to_table(self, param):
"""Returns the table object for the given param object."""
if isinstance(param, (sa.Column, sa.Index, sa.schema.Constraint)):
ret = param.table
else:
ret = param
return ret
def _to_table_name(self, param):
"""Returns the table name for the given param object."""
ret = self._to_table(param)
if isinstance(ret, sa.Table):
ret = ret.fullname
return ret
def _do_quote_table_identifier(self, identifier):
"""Returns a quoted version of the given table identifier."""
return '"%s"'%identifier
def start_alter_table(self, param):
"""Returns the start of an ``ALTER TABLE`` SQL-Statement.
Use the param object to determine the table name and use it
for building the SQL statement.
:param param: object to determine the table from. This may be
a :class:`sqlalchemy.Column`, an :class:`sqlalchemy.Index`,
a :class:`sqlachemy.schema.Constraint`, a
:class:`sqlalchemy.Table` or a table name string
"""
table = self._to_table(param)
table_name = self._to_table_name(table)
self.append('\nALTER TABLE %s ' % self._do_quote_table_identifier(table_name))
self.append('\nALTER TABLE %s ' % \
self._do_quote_table_identifier(table_name))
return table
def _pk_constraint(self, table, column, status):
"""Create a primary key constraint from a table, column
"""Create a primary key constraint from a table, column.
Status: true if the constraint is being added; false if being dropped
"""
if isinstance(column, basestring):
@ -59,12 +76,11 @@ class RawAlterTableVisitor(object):
ret.name = pk
return ret
class AlterTableVisitor(SchemaIterator, RawAlterTableVisitor):
"""Common operations for 'alter table' statements"""
from sqlalchemy.schema import ForeignKeyConstraint
class ANSIColumnGenerator(AlterTableVisitor, SchemaGenerator):
"""Extends ansisql generator for column creation (alter table add col)"""
#def __init__(self, *args, **kwargs):
@ -96,38 +112,44 @@ class ANSIColumnGenerator(AlterTableVisitor,SchemaGenerator):
# else:
self.execute()
def visit_table(self, table):
pass
class ANSIColumnDropper(AlterTableVisitor):
"""Extends ansisql dropper for column dropping (alter table drop col)"""
"""Extends ANSI SQL dropper for column dropping (``ALTER TABLE
DROP COLUMN``)."""
def visit_column(self, column):
"""Drop a column; #33"""
table = self.start_alter_table(column)
self.append(' DROP COLUMN %s'%self._do_quote_column_identifier(column.name))
self.append(' DROP COLUMN %s' % \
self._do_quote_column_identifier(column.name))
self.execute()
#if column.primary_key:
# cons = self._pk_constraint(table,column,False)
# cons.create()
class ANSISchemaChanger(AlterTableVisitor, SchemaGenerator):
"""Manages changes to existing schema elements.
Note that columns are schema elements; "alter table add column" is in
SchemaGenerator.
Note that columns are schema elements; ``ALTER TABLE ADD COLUMN``
is in SchemaGenerator.
All items may be renamed. Columns can also have many of their properties -
type, for example - changed.
Each function is passed a tuple, containing (object,name); where object
is a type of object you'd expect for that function (ie. table for
visit_table) and name is the object's new name. NONE means the name is
unchanged.
Each function is passed a tuple, containing (object,name); where
object is a type of object you'd expect for that function
(ie. table for visit_table) and name is the object's new
name. NONE means the name is unchanged.
"""
def _do_quote_column_identifier(self, identifier):
"""override this function to define how identifiers (table and column names) should be written in the sql.
for instance, in postgres, double quotes should surround the identifier
"""override this function to define how identifiers (table and
column names) should be written in the SQL. For instance, in
PostgreSQL, double quotes should surround the identifier
"""
return identifier
@ -147,7 +169,8 @@ class ANSISchemaChanger(AlterTableVisitor,SchemaGenerator):
if 'nullable' in keys:
self._run_subvisit(delta, self._visit_column_nullable)
if 'server_default' in keys:
# Skip 'default': only handle server-side defaults, others are managed by the app, not the db.
# Skip 'default': only handle server-side defaults, others
# are managed by the app, not the db.
self._run_subvisit(delta, self._visit_column_default)
#if 'primary_key' in keys:
# #self._run_subvisit(delta,self._visit_column_primary_key)
@ -156,6 +179,7 @@ class ANSISchemaChanger(AlterTableVisitor,SchemaGenerator):
# self._visit_column_foreign_key(delta)
if 'name' in keys:
self._run_subvisit(delta, self._visit_column_name)
def _run_subvisit(self, delta, func, col_name=None, table_name=None):
if table_name is None:
table_name = self._to_table(delta.table)
@ -178,6 +202,7 @@ class ANSISchemaChanger(AlterTableVisitor,SchemaGenerator):
column_foreign_key = None
cons.drop()
cons.create()
def _visit_column_primary_key(self, delta):
table = delta.table
col = getattr(table.c, delta.current_name)
@ -185,26 +210,31 @@ class ANSISchemaChanger(AlterTableVisitor,SchemaGenerator):
cons = self._pk_constraint(table, col, pk)
cons.drop()
cons.create()
def _visit_column_nullable(self, table_name, col_name, delta):
nullable = delta['nullable']
table = self._to_table(delta)
self.start_alter_table(table_name)
self.append("ALTER COLUMN %s "%self._do_quote_column_identifier(col_name))
self.append("ALTER COLUMN %s " % \
self._do_quote_column_identifier(col_name))
if nullable:
self.append("DROP NOT NULL")
else:
self.append("SET NOT NULL")
def _visit_column_default(self, table_name, col_name, delta):
server_default = delta['server_default']
# Dummy column: get_col_default_string needs a column for some reason
dummy = sa.Column(None, None, server_default=server_default)
default_text = self.get_column_default_string(dummy)
self.start_alter_table(table_name)
self.append("ALTER COLUMN %s "%self._do_quote_column_identifier(col_name))
self.append("ALTER COLUMN %s " % \
self._do_quote_column_identifier(col_name))
if default_text is not None:
self.append("SET DEFAULT %s"%default_text)
else:
self.append("DROP DEFAULT")
def _visit_column_type(self, table_name, col_name, delta):
type = delta['type']
if not isinstance(type, sa.types.AbstractType):
@ -213,11 +243,16 @@ class ANSISchemaChanger(AlterTableVisitor,SchemaGenerator):
#type_text = type.engine_impl(self.engine).get_col_spec()
type_text = type.dialect_impl(self.dialect).get_col_spec()
self.start_alter_table(table_name)
self.append("ALTER COLUMN %s TYPE %s"%(self._do_quote_column_identifier(col_name),type_text))
self.append("ALTER COLUMN %s TYPE %s" % \
(self._do_quote_column_identifier(col_name),
type_text))
def _visit_column_name(self, table_name, col_name, delta):
new_name = delta['name']
self.start_alter_table(table_name)
self.append('RENAME COLUMN %s TO %s'%(self._do_quote_column_identifier(col_name), self._do_quote_column_identifier(new_name)))
self.append('RENAME COLUMN %s TO %s' % \
(self._do_quote_column_identifier(col_name),
self._do_quote_column_identifier(new_name)))
def visit_index(self, param):
"""Rename an index; #36"""
@ -230,10 +265,11 @@ class ANSISchemaChanger(AlterTableVisitor,SchemaGenerator):
class ANSIConstraintCommon(AlterTableVisitor):
"""
Migrate's constraints require a separate creation function from SA's:
Migrate's constraints are created independently of a table; SA's are
created at the same time as the table.
Migrate's constraints require a separate creation function from
SA's: Migrate's constraints are created independently of a table;
SA's are created at the same time as the table.
"""
def get_constraint_name(self, cons):
if cons.name is not None:
ret = cons.name
@ -241,7 +277,9 @@ class ANSIConstraintCommon(AlterTableVisitor):
ret = cons.name = cons.autoname()
return ret
class ANSIConstraintGenerator(ANSIConstraintCommon):
def get_constraint_specification(self, cons, **kwargs):
if isinstance(cons, constraint.PrimaryKeyConstraint):
col_names = ','.join([i.name for i in cons.columns])
@ -263,6 +301,7 @@ class ANSIConstraintGenerator(ANSIConstraintCommon):
else:
raise exceptions.InvalidConstraintError(cons)
return ret
def _visit_constraint(self, constraint):
table = self.start_alter_table(constraint)
self.append("ADD ")
@ -279,7 +318,9 @@ class ANSIConstraintGenerator(ANSIConstraintCommon):
def visit_migrate_check_constraint(self, *p, **k):
return self._visit_constraint(*p, **k)
class ANSIConstraintDropper(ANSIConstraintCommon):
def _visit_constraint(self, constraint):
self.start_alter_table(constraint)
self.append("DROP CONSTRAINT ")
@ -295,8 +336,10 @@ class ANSIConstraintDropper(ANSIConstraintCommon):
def visit_migrate_check_constraint(self, *p, **k):
return self._visit_constraint(*p, **k)
class ANSIFKGenerator(AlterTableVisitor, SchemaGenerator):
"""Extends ansisql generator for column creation (alter table add col)"""
def __init__(self, *args, **kwargs):
self.fk = kwargs.get('fk', None)
if self.fk:
@ -315,6 +358,7 @@ class ANSIFKGenerator(AlterTableVisitor,SchemaGenerator):
def visit_table(self, table):
pass
class ANSIDialect(object):
columngenerator = ANSIColumnGenerator
columndropper = ANSIColumnDropper
@ -324,5 +368,6 @@ class ANSIDialect(object):
@classmethod
def visitor(self, name):
return getattr(self, name)
def reflectconstraints(self, connection, table_name):
raise NotImplementedError()