[Sqlalchemy-tickets] [sqlalchemy] #2814: support for overriding existing @compiles directives

[sqlalchemy <mi...@zz...>]

#2814: support for overriding existing @compiles directives
-------------------------+------------------------------------
 Reporter:  zzzeek       |           Owner:  zzzeek
     Type:  enhancement  |          Status:  new
 Priority:  medium       |       Milestone:  0.9.xx
Component:  ext          |        Severity:  major - 1-3 hours
 Keywords:               |  Progress State:  in queue
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 perhaps sending it in as a **kw.

 {{{
 #!python
 from sqlalchemy.ext.compiler import compiles
 from alembic.ddl.base import AddColumn

 # ideally, the @compiles system would have some way of getting
 # us the "existing" @compiles decorator, so this part is the
 # hack
 specs = AddColumn.__dict__.get('_compiler_dispatcher').specs
 existing_dispatch = specs.get('mysql', specs['default'])

 @compiles(AddColumn, "mysql")
 def add_column(element, compiler, **kw):
     text = existing_dispatch(element, compiler, **kw)
     if "after" in element.column.info:
         text += " AFTER %s" % element.column.info['after']
     return text

 from sqlalchemy import Column, Integer
 from alembic.migration import MigrationContext
 from alembic.operations import Operations

 ctx = MigrationContext.configure(dialect_name="mysql", opts={"as_sql":
 True})
 op = Operations(ctx)

 op.add_column("t", Column('y', Integer))

 op.add_column("t", Column('x', Integer, info={"after": "y"}))
 }}}

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Ticket URL: <http://www.sqlalchemy.org/trac/ticket/2814>
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