Rails - Jan 2011 - Active Record Join does not return catesian product

I’m trying to join two tables with active record and not getting what I
expect *surprise*.

Two tables T1 and T2, both have a common key called ID.  Given this
relationship in the Models

class T1 < ActiveRecord::Base
  has_one :T2

class T1 < ActiveRecord::Base
  belongs_to :T1

In the controller I have…
  @results = T1.all(:joins => :T2)
  @results only contains the columns from T1 and none from T2.

If I do a find_by_sql as follows
  @results = T1.find_by_sql("select * from T1, T2 where T1.id =
T2.id")
  @results contains the correct Cartesian product of T1, T2.

Am I missing something in the active record call?

Thanks in advance for your time...
jeff...

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Jeffrey H. wrote in post #975932:
> I’m trying to join two tables with active record and not getting what I
> expect *surprise*.
>
> Two tables T1 and T2, both have a common key called ID.  Given this
> relationship in the Models
>
> class T1 < ActiveRecord::Base
>   has_one :T2
>
> class T1 < ActiveRecord::Base
>   belongs_to :T1
>
> In the controller I have…
>   @results = T1.all(:joins => :T2)
>   @results only contains the columns from T1 and none from T2.
>
> If I do a find_by_sql as follows
>   @results = T1.find_by_sql("select * from T1, T2 where T1.id =
T2.id")
>   @results contains the correct Cartesian product of T1, T2.
>
> Am I missing something in the active record call?
No; rather, you''re missing something in the setup.  Normally the
foreign
key for t2 would be t1.t2_id , not simply t1.id .

I think your DB design has problems, frankly.  You shouldn''t normally
be
trying to match the primary key in one table with the primary key in 
another.  What are you trying to achieve here?
>
> Thanks in advance for your time...
> jeff...
Best,
-- 
Marnen Laibow-Koser
http://www.marnen.org
marnen-sbuyVjPbboAdnm+yROfE0A@public.gmane.org

Sent from my iPhone

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On Jan 19, 4:14 am, "Jeffrey H."
<li...-fsXkhYbjdPsEEoCn2XhGlw@public.gmane.org>
wrote:
> I’m trying to join two tables with active record and not getting what I
> expect *surprise*.
>
> Two tables T1 and T2, both have a common key called ID.  Given this
> relationship in the Models
>
> class T1 < ActiveRecord::Base
>   has_one :T2
>
> class T1 < ActiveRecord::Base
>   belongs_to :T1
>
> In the controller I have…
>   @results = T1.all(:joins => :T2)
>   @results only contains the columns from T1 and none from T2.
>
The select clause defaults to t1.* If you want something else you have
to ask for it

Fred
> If I do a find_by_sql as follows
>   @results = T1.find_by_sql("select * from T1, T2 where T1.id =
T2.id")
>   @results contains the correct Cartesian product of T1, T2.
>
> Am I missing something in the active record call?
>
> Thanks in advance for your time...
> jeff...
>
> --
> Posted viahttp://www.ruby-forum.com/.
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