Rails - Feb 2006 - Creating objects with has_many :through relationship

Three tables:

users: id

clients: id

admin_contacts: user_id, client_id


class Client
  has_many :admin_contacts
  has_many :contacts, :through => :admin_contacts, :foreign_key =>
:user_id,
:class_name => ''User''
end


I added the :contacts for ease of use of grabbing the user objects
associated with the admin_contact.

This all works great, I can grab the Users that are admin_contacts for the
client by doing:

users = client.contacts => Array of User objects defined in the
admin_contacts table

To add admin_contacts to a client:

client.admin_contacts << AdminContact.new( :user => user_object )

I also thought this would work, but doesn''t:

client.contacts << user_object

Is this something that should work?


Bob Silva
http://www.railtie.net/

I had the same problem. The way I ''solved'' it was:

 ac = AdminContact.new
 ac.user = user_object
 client.admin_contacts << ac

Why _that_ worked and the other does not, I do not
know but would be willing to hear from someone more
expert than me.

Rob

> Three tables:
>
> users: id
>
> clients: id
>
> admin_contacts: user_id, client_id
>
>
> class Client
>   has_many :admin_contacts
>   has_many :contacts, :through => :admin_contacts, :foreign_key =>
> :user_id,
> :class_name => ''User''
> end
>
>
> I added the :contacts for ease of use of grabbing the user objects
> associated with the admin_contact.
>
> This all works great, I can grab the Users that are admin_contacts for the
> client by doing:
>
> users = client.contacts => Array of User objects defined in the
> admin_contacts table
>
> To add admin_contacts to a client:
>
> client.admin_contacts << AdminContact.new( :user => user_object )
>
> I also thought this would work, but doesn''t:
>
> client.contacts << user_object
>
> Is this something that should work?
>
>
> Bob Silva
> http://www.railtie.net/
>
>
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>

Hi Rob,
>  ac = AdminContact.new
>  ac.user = user_object
>  client.admin_contacts << ac
and
> client.admin_contacts << AdminContact.new( :user => user_object )
are equivalent.

I would think that :through associations have save capabilities. Anyone
smarter than us know the answer? Surely Rick or Ezra know!?!?

Bob Silva
http://www.railtie.net/

> -----Original Message-----
> From: rails-bounces@lists.rubyonrails.org [mailto:rails-
> bounces@lists.rubyonrails.org] On Behalf Of rgordon@mwt.net
> Sent: Saturday, February 25, 2006 8:43 PM
> To: rails@lists.rubyonrails.org
> Subject: Re: [Rails] Creating objects with has_many :through relationship
> 
> I had the same problem. The way I ''solved'' it was:
> 
>  ac = AdminContact.new
>  ac.user = user_object
>  client.admin_contacts << ac
> 
> Why _that_ worked and the other does not, I do not
> know but would be willing to hear from someone more
> expert than me.
> 
> Rob
> 
> 
> > Three tables:
> >
> > users: id
> >
> > clients: id
> >
> > admin_contacts: user_id, client_id
> >
> >
> > class Client
> >   has_many :admin_contacts
> >   has_many :contacts, :through => :admin_contacts, :foreign_key
=>
> > :user_id,
> > :class_name => ''User''
> > end
> >
> >
> > I added the :contacts for ease of use of grabbing the user objects
> > associated with the admin_contact.
> >
> > This all works great, I can grab the Users that are admin_contacts for
> the
> > client by doing:
> >
> > users = client.contacts => Array of User objects defined in the
> > admin_contacts table
> >
> > To add admin_contacts to a client:
> >
> > client.admin_contacts << AdminContact.new( :user =>
user_object )
> >
> > I also thought this would work, but doesn''t:
> >
> > client.contacts << user_object
> >
> > Is this something that should work?
> >
> >
> > Bob Silva
> > http://www.railtie.net/
> >
> >
> > _______________________________________________
> > Rails mailing list
> > Rails@lists.rubyonrails.org
> > http://lists.rubyonrails.org/mailman/listinfo/rails
> >
> 
> 
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails

> Hi Rob,
>
>>  ac = AdminContact.new
>>  ac.user = user_object
>>  client.admin_contacts << ac
>
> and
>
>> client.admin_contacts << AdminContact.new( :user =>
user_object )
>
> are equivalent.
I know, I *understand* them as equivalent, I just did not
experience them as such, neither on my linux both nor
on windows.

I came upon this by absolutely gutting the related
classes and putting back together one line at a time
including a re-gen of db and scaffolding.

It was only when I made the above change did I get it to work.

Here is stack from my original 2/23 post. Is this similar to
what you are seeing?


You have a nil object when you didn''t expect it!
You might have expected an instance of Array.
The error occured while evaluating nil.[]

RAILS_ROOT: ./script/../config/..
Application Trace | Framework Trace | Full Trace

c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.13.2/lib/active_record/base.rb:1509:in
`read_attribute''
c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.13.2/lib/active_record/base.rb:1198:in
`id''


c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.13.2/lib/active_record/base.rb:1209:in
`quoted_id''
c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.13.2/lib/active_record/associations/has_many_association.rb:169:in
`construct_sql''


c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.13.2/lib/active_record/associations/has_many_association.rb:8:in
`initialize''
c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.13.2/lib/active_record/associations.rb:753:in
`new''


c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.13.2/lib/active_record/associations.rb:753:in
`endorsees''
c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.13.2/lib/active_record/associations.rb:749:in
`endorsees''

#{RAILS_ROOT}/app/controllers/claim_admin_controller.rb:50:in `create''

#{RAILS_ROOT}/app/controllers/claim_admin_controller.rb:47:in `each''
#{RAILS_ROOT}/app/controllers/claim_admin_controller.rb:47:in `create''

#{RAILS_ROOT}/app/controllers/claim_admin_controller.rb:32:in `each''

#{RAILS_ROOT}/app/controllers/claim_admin_controller.rb:32:in
`create''
>
> I would think that :through associations have save capabilities. Anyone
> smarter than us know the answer? Surely Rick or Ezra know!?!?
>
> Bob Silva
> http://www.railtie.net/
>
>
>> -----Original Message-----
>> From: rails-bounces@lists.rubyonrails.org [mailto:rails-
>> bounces@lists.rubyonrails.org] On Behalf Of rgordon@mwt.net
>> Sent: Saturday, February 25, 2006 8:43 PM
>> To: rails@lists.rubyonrails.org
>> Subject: Re: [Rails] Creating objects with has_many :through
>> relationship
>>
>> I had the same problem. The way I ''solved'' it was:
>>
>>  ac = AdminContact.new
>>  ac.user = user_object
>>  client.admin_contacts << ac
>>
>> Why _that_ worked and the other does not, I do not
>> know but would be willing to hear from someone more
>> expert than me.
>>
>> Rob
>>
>>
>> > Three tables:
>> >
>> > users: id
>> >
>> > clients: id
>> >
>> > admin_contacts: user_id, client_id
>> >
>> >
>> > class Client
>> >   has_many :admin_contacts
>> >   has_many :contacts, :through => :admin_contacts, :foreign_key
=>
>> > :user_id,
>> > :class_name => ''User''
>> > end
>> >
>> >
>> > I added the :contacts for ease of use of grabbing the user objects
>> > associated with the admin_contact.
>> >
>> > This all works great, I can grab the Users that are admin_contacts
for
>> the
>> > client by doing:
>> >
>> > users = client.contacts => Array of User objects defined in the
>> > admin_contacts table
>> >
>> > To add admin_contacts to a client:
>> >
>> > client.admin_contacts << AdminContact.new( :user =>
user_object )
>> >
>> > I also thought this would work, but doesn''t:
>> >
>> > client.contacts << user_object
>> >
>> > Is this something that should work?
>> >
>> >
>> > Bob Silva
>> > http://www.railtie.net/
>> >
>> >
>> > _______________________________________________
>> > Rails mailing list
>> > Rails@lists.rubyonrails.org
>> > http://lists.rubyonrails.org/mailman/listinfo/rails
>> >
>>
>>
>> _______________________________________________
>> Rails mailing list
>> Rails@lists.rubyonrails.org
>> http://lists.rubyonrails.org/mailman/listinfo/rails
>
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>

Bob-

	I ran into a similar problem trying to save objects across  
the :through relationship name like your :contacts. Its been a little  
while(2-3 weeks?) since I ran into the problem and dug into the  
source of :through. I ended up with the conclusion that it wasn''t in  
there to make that work correctly yet. It might have changed, I  
haven''t had a lot of time recently to troll over the patch list on  
trac. But last time I ran into this it was an equal pain as you are  
having now and so i ended up not using :through relationship names to  
save related objects through like that.

	It seems like a natural thing to want to do though, I mean save  
objects using the through set up. Not sure what the best workaround  
is right now.

-Ezra

	
On Feb 25, 2006, at 8:34 PM, Bob Silva wrote:
> Three tables:
>
> users: id
>
> clients: id
>
> admin_contacts: user_id, client_id
>
>
> class Client
>   has_many :admin_contacts
>   has_many :contacts, :through => :admin_contacts, :foreign_key  
> => :user_id,
> :class_name => ''User''
> end
>
>
> I added the :contacts for ease of use of grabbing the user objects
> associated with the admin_contact.
>
> This all works great, I can grab the Users that are admin_contacts  
> for the
> client by doing:
>
> users = client.contacts => Array of User objects defined in the
> admin_contacts table
>
> To add admin_contacts to a client:
>
> client.admin_contacts << AdminContact.new( :user => user_object )
>
> I also thought this would work, but doesn''t:
>
> client.contacts << user_object
>
> Is this something that should work?
>
>
> Bob Silva
> http://www.railtie.net/
>
>
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>