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import functools
from sqlalchemy.ext.compiler import compiles
from sqlalchemy.schema import DDLElement
from sqlalchemy import types as sqltypes
class AlterTable(DDLElement):
"""Represent an ALTER TABLE statement.
Only the string name and optional schema name of the table
is required, not a full Table object.
"""
def __init__(self, table_name, schema=None):
self.table_name = table_name
self.schema = schema
class RenameTable(AlterTable):
def __init__(self, old_table_name, new_table_name, schema=None):
super(RenameTable, self).__init__(old_table_name, schema=schema)
self.new_table_name = new_table_name
class AlterColumn(AlterTable):
def __init__(self, name, column_name, schema=None,
existing_type=None,
existing_nullable=None,
existing_server_default=None):
super(AlterColumn, self).__init__(name, schema=schema)
self.column_name = column_name
self.existing_type=sqltypes.to_instance(existing_type) \
if existing_type is not None else None
self.existing_nullable=existing_nullable
self.existing_server_default=existing_server_default
class ColumnNullable(AlterColumn):
def __init__(self, name, column_name, nullable, **kw):
super(ColumnNullable, self).__init__(name, column_name,
**kw)
self.nullable = nullable
class ColumnType(AlterColumn):
def __init__(self, name, column_name, type_, **kw):
super(ColumnType, self).__init__(name, column_name,
**kw)
self.type_ = sqltypes.to_instance(type_)
class ColumnName(AlterColumn):
def __init__(self, name, column_name, newname, **kw):
super(ColumnName, self).__init__(name, column_name, **kw)
self.newname = newname
class ColumnDefault(AlterColumn):
def __init__(self, name, column_name, default, **kw):
super(ColumnDefault, self).__init__(name, column_name, **kw)
self.default = default
class AddColumn(AlterTable):
def __init__(self, name, column, schema=None):
super(AddColumn, self).__init__(name, schema=schema)
self.column = column
class DropColumn(AlterTable):
def __init__(self, name, column, schema=None):
super(DropColumn, self).__init__(name, schema=schema)
self.column = column
@compiles(RenameTable)
def visit_rename_table(element, compiler, **kw):
return "%s RENAME TO %s" % (
alter_table(compiler, element.table_name, element.schema),
format_table_name(compiler, element.new_table_name, element.schema)
)
@compiles(AddColumn)
def visit_add_column(element, compiler, **kw):
return "%s %s" % (
alter_table(compiler, element.table_name, element.schema),
add_column(compiler, element.column, **kw)
)
@compiles(DropColumn)
def visit_drop_column(element, compiler, **kw):
return "%s %s" % (
alter_table(compiler, element.table_name, element.schema),
drop_column(compiler, element.column.name, **kw)
)
@compiles(ColumnNullable)
def visit_column_nullable(element, compiler, **kw):
return "%s %s %s" % (
alter_table(compiler, element.table_name, element.schema),
alter_column(compiler, element.column_name),
"DROP NOT NULL" if element.nullable else "SET NOT NULL"
)
@compiles(ColumnType)
def visit_column_type(element, compiler, **kw):
return "%s %s %s" % (
alter_table(compiler, element.table_name, element.schema),
alter_column(compiler, element.column_name),
"TYPE %s" % compiler.dialect.type_compiler.process(element.type_)
)
@compiles(ColumnName)
def visit_column_name(element, compiler, **kw):
return "%s RENAME %s TO %s" % (
alter_table(compiler, element.table_name, element.schema),
format_column_name(compiler, element.column_name),
format_column_name(compiler, element.newname)
)
def quote_dotted(name, quote):
"""quote the elements of a dotted name"""
result = '.'.join([quote(x) for x in name.split('.')])
return result
def format_table_name(compiler, name, schema):
quote = functools.partial(compiler.preparer.quote, force=None)
if schema:
return quote_dotted(schema, quote) + "." + quote(name)
else:
return quote(name)
def format_column_name(compiler, name):
return compiler.preparer.quote(name, None)
def alter_table(compiler, name, schema):
return "ALTER TABLE %s" % format_table_name(compiler, name, schema)
def drop_column(compiler, name):
return 'DROP COLUMN %s' % format_column_name(compiler, name)
def alter_column(compiler, name):
return 'ALTER COLUMN %s' % format_column_name(compiler, name)
def add_column(compiler, column, **kw):
return "ADD COLUMN %s" % compiler.get_column_specification(column, **kw)
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