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6ab79eb412
Adding a column is implemented for mysql, postgresql and sqlite. Droping and altering a column is only implemented for mysql and postgresql for the moment. Quick&dirty tests has been done for sqlite and mysql only.
90 lines
3.5 KiB
Python
90 lines
3.5 KiB
Python
# -*- coding: utf-8 -*-
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import os
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import sqlalchemy as sqla
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from sqlalchemy.ext.compiler import compiles
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## @file sqlalter.py
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# This file defines all DDL (data definition langage) for the ALTER TABLE instructions
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#
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# It uses the SqlAlchemy compilation and quoting methos to generate SQL
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class AddColumn(sqla.schema.DDLElement):
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""" Defines the ddl for adding a column to a table """
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def __init__(self,table, column):
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""" Instanciate the DDL
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@param table sqlalchemy.Table: A sqlalchemy table object
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@param column sqlalchemy.Column: A sqlalchemy column object
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"""
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self.col = column
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self.table = table
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@compiles(AddColumn, 'mysql')
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@compiles(AddColumn, 'postgresql')
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@compiles(AddColumn, 'sqlite')
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def visit_add_column(element, ddlcompiler, **kw):
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""" Compiles the AddColumn DDL for mysql, postgresql and sqlite"""
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prep = ddlcompiler.sql_compiler.preparer
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tname = prep.format_table(element.table)
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colname = prep.format_column(element.col)
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return 'ALTER TABLE %s ADD COLUMN %s %s'%(tname, colname, element.col.type)
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@compiles(AddColumn)
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def visit_add_column(element, ddlcompiler, **kw):
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raise NotImplementedError('Add column not yet implemented for '+str(ddlcompiler.dialect.name))
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class DropColumn(sqla.schema.DDLElement):
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""" Defines the DDL for droping a column from a table """
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def __init__(self, table, column):
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""" Instanciate the DDL
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@param table sqlalchemy.Table: A sqlalchemy table object
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@param column sqlalchemy.Column: A sqlalchemy column object representing the column to drop
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"""
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self.col = column
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self.table = table
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@compiles(DropColumn,'mysql')
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@compiles(DropColumn, 'postgresql')
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def visit_drop_column(element, ddlcompiler, **kw):
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""" Compiles the DropColumn DDL for mysql & postgresql """
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prep = ddlcompiler.sql_compiler.preparer
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tname = prep.format_table(element.table)
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colname = prep.format_column(element.col)
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return 'ALTER TABLE %s DROP COLUMN %s'%(tname, colname)
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@compiles(DropColumn)
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def visit_drop_column(element, ddlcompiler, **kw):
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raise NotImplementedError('Drop column not yet implemented for '+str(ddlcompiler.dialect.name))
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class AlterColumn(sqla.schema.DDLElement):
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""" Defines the DDL for changing the type of a column """
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def __init__(self, table, column):
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""" Instanciate the DDL
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@param table sqlalchemy.Table: A sqlalchemy Table object
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@param column sqlalchemy.Column: A sqlalchemy Column object representing the new column
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"""
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self.col = column
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self.table = table
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@compiles(AlterColumn, 'mysql')
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def visit_alter_column(element, ddlcompiler, **kw):
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""" Compiles the AlterColumn DDL for mysql """
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prep = ddlcompiler.sql_compiler.preparer
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tname = prep.format_table(element.table)
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colname = prep.format_column(element.col)
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return 'ALTER TABLE %s ALTER COLUMN %s %s'%(tname, colname, element.col.type)
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@compiles(AlterColumn, 'postgresql')
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def visit_alter_column(element, ddlcompiler, **kw):
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""" Compiles the AlterColumn DDL for postgresql """
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prep = ddlcompiler.sql_compiler.preparer
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tname = prep.format_table(element.table)
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colname = prep.format_column(element.col)
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return 'ALTER TABLE %s ALTER COLUMN %s TYPE %s'%(tname, colname, element.col.type)
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@compiles(AlterColumn)
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def visit_alter_column(element, ddlcompiler, **kw):
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raise NotImplementedError('Alter column not yet implemented for '+str(ddlcompiler.dialect.name))
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