Rails - Jan 2006 - single table inheritance: change object ''type'' after create?

Hey folks,

I''m trying to keep track of couple of different kinds of
"entities" in
my rails app: "people", "organizations", and
"committees".  I have a
single Entities table in the database, and I''m using Single Table 
Inheritance to keep the different subclasses in the same table, with a 
field "type".

My problem comes when allowing the user to correct a mistake -- say, 
change a "committee" to a more general "organization". 
@entity.update_attributes({:type=>"Organization"}) doesn''t
change the
database.  I can understand that ruby doesn''t want me changing the
class
of an existing object.  However, is there a way I can make this change, 
while keeping the entity''s same "id" (so I don''t
have to change
everywhere that''s referenced)?

Thanks a bunch for your help,
Asa

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Posted via http://www.ruby-forum.com/.

Asa Hopkins wrote:
> I''m trying to keep track of couple of different kinds of
"entities" in
> my rails app: "people", "organizations", and
"committees".  I have a
> single Entities table in the database, and I''m using Single Table 
> Inheritance to keep the different subclasses in the same table, with a 
> field "type".
> 
> My problem comes when allowing the user to correct a mistake -- say, 
> change a "committee" to a more general "organization". 
> @entity.update_attributes({:type=>"Organization"})
doesn''t change the
> database.  I can understand that ruby doesn''t want me changing the
class
> of an existing object.  However, is there a way I can make this change, 
> while keeping the entity''s same "id" (so I
don''t have to change
> everywhere that''s referenced)?
The STI "type" attribute is protected from mass assignment, so instead
use:

    @entity.update_attribute( :type, ''Organization'' )

or

    @entity[:type] = ...
    ...
    @entity.save


-- 
We develop, watch us RoR, in numbers too big to ignore.

Thanks!  That worked right away.

Asa

Mark Reginald James wrote:
> 
> The STI "type" attribute is protected from mass assignment, so
instead
> use:
> 
>     @entity.update_attribute( :type, ''Organization'' )
> 
> or
> 
>     @entity[:type] = ...
>     ...
>     @entity.save
> 
> 
> --
> We develop, watch us RoR, in numbers too big to ignore.

-- 
Posted via http://www.ruby-forum.com/.