Index() throws an AttributeError when called with an object using declarative base

[Former user]

Currently, Index() can't be called with an object using the declarative layer. The result is:

AttributeError: 'InstrumentedAttribute' object has no attribute 'table'

However, using the columns directly works fine, but looks a bit ugly:

Index('viewforum', Topic.__table__.c.forum_id,
      Topic.__table__.c.sticky, Topic.__table__.c.last_post_id)

Many thanks,[BR] Christoph (aka tux21b)

[Mike Bayer]

though this is problematic; if you say Index('foo', MyClass.foo), its going to force compilation of MyClass' mapper, which can cause problems if dependent classes and tables have not yet been defined. We might further want Index to defer getting the list of columns until create() is called, but then if your mapping has problems, you're going to have ORM errors within metadata.create_all() which is pretty nasty.

So it might be nice to get change the frigging _CompileOnAttr nastiness to be more of a complete InstrumentedAttribute at mapper construction time. A quick workaround would be to put a working __clause_element__() method on _CompileOnAttr.

[Former user]

(original author: ged)

[Mike Bayer]

implemented in 209e888e1bda69924b364ae3394016acef0e9d41.

[Mike Bayer]

Removing milestone: 0.5.xx (automated comment)