Hi I have a has_many :through. It''s a basic mapping of Project id .... User id .... TeamMembers project_id user_id role What I would like to do is have different roles so I can have in the project model has_many :core_members, :through => :team_members, :source => :user but I would like to limit this to only those with the "core" role in the team members table for this project. Any ideas? -------------- next part -------------- An HTML attachment was scrubbed... URL: http://wrath.rubyonrails.org/pipermail/rails/attachments/20060510/216edd1c/attachment.html
On 5/10/06, Daniel N <has.sox@gmail.com> wrote: [...]> What I would like to do is have different roles so I can have in the project > model > > has_many :core_members, :through => :team_members, :source => :user > > but I would like to limit this to only those with the "core" role in the > team members table for this project. > > Any ideas?You can specify :conditions in your has_many statement. So for example: has_many :core_members, :through => :team_members, :source => :user, :conditions => "team_members.role = ''core''" or similar. -- Bosko Milekic <bosko.milekic@gmail.com>
Thanx Bosko, That worked great. I have one question for this tho... How do I have a has_one for this situation where the role is leader? ie each project only has_one :leader but I can''t specify the through condition. I don''t really want to put a leader_id field in the projects table. I would like to keep all team members regardless of their role in the team_members table. Any ideas how I could do this? I have tried for quite a few hours now and the only way I have found to impelment it is to write my own leader and leader= methods in the project model. On 5/11/06, Bosko Milekic <bosko.milekic@gmail.com> wrote:> > On 5/10/06, Daniel N <has.sox@gmail.com> wrote: > [...] > > What I would like to do is have different roles so I can have in the > project > > model > > > > has_many :core_members, :through => :team_members, :source => :user > > > > but I would like to limit this to only those with the "core" role in the > > team members table for this project. > > > > Any ideas? > > You can specify :conditions in your has_many statement. So for example: > > has_many :core_members, :through => :team_members, :source => :user, > :conditions => "team_members.role = ''core''" > > or similar. > > -- > Bosko Milekic <bosko.milekic@gmail.com> > _______________________________________________ > Rails mailing list > Rails@lists.rubyonrails.org > http://lists.rubyonrails.org/mailman/listinfo/rails >-------------- next part -------------- An HTML attachment was scrubbed... URL: http://wrath.rubyonrails.org/pipermail/rails/attachments/20060510/b9db9013/attachment.html
Bosko Milekic wrote:> On 5/10/06, Daniel N <has.sox@gmail.com> wrote: >> What I would like to do is have different roles so I can have in the project >> model >> >> has_many :core_members, :through => :team_members, :source => :user >> >> but I would like to limit this to only those with the "core" role in the >> team members table for this project. >> >> Any ideas? > > You can specify :conditions in your has_many statement. So for example: > > has_many :core_members, :through => :team_members, :source => :user, > :conditions => "team_members.role = ''core''" > > or similar.That works just fine, but I like to do it with a special association in the join model, then use that as the :source in the containing model. That localizes the condition to the proper scope, allows potential reuse, and best of all you don''t have to name the table in the :conditions. I have a full example of that on my blog (and the :uniq stuff might be useful in this situation as well): http://blog.hasmanythrough.com/articles/2006/05/06/through_gets_uniq By the way, Daniel, there is no has_one :through association. -- Josh Susser http://blog.hasmanythrough.com -- Posted via http://www.ruby-forum.com/.
Hi Josh, Thanx for the eplaination. I''ve been to your blog. I have found it very useful. Thanx. I have read your article that you mentioned but it must of been too late or something because I just couldn''t quite get my head around the relationships that you had. Also I don''t have the uniq option. I''m assuming that this is only available for those on the edge. On 5/11/06, Josh Susser <josh@hasmanythrough.com> wrote:> > Bosko Milekic wrote: > > On 5/10/06, Daniel N <has.sox@gmail.com> wrote: > >> What I would like to do is have different roles so I can have in the > project > >> model > >> > >> has_many :core_members, :through => :team_members, :source => :user > >> > >> but I would like to limit this to only those with the "core" role in > the > >> team members table for this project. > >> > >> Any ideas? > > > > You can specify :conditions in your has_many statement. So for example: > > > > has_many :core_members, :through => :team_members, :source => :user, > > :conditions => "team_members.role = ''core''" > > > > or similar. > > That works just fine, but I like to do it with a special association in > the join model, then use that as the :source in the containing model. > That localizes the condition to the proper scope, allows potential > reuse, and best of all you don''t have to name the table in the > :conditions. I have a full example of that on my blog (and the :uniq > stuff might be useful in this situation as well): > http://blog.hasmanythrough.com/articles/2006/05/06/through_gets_uniq > > By the way, Daniel, there is no has_one :through association. > > -- > Josh Susser > http://blog.hasmanythrough.com > > -- > Posted via http://www.ruby-forum.com/. > _______________________________________________ > Rails mailing list > Rails@lists.rubyonrails.org > http://lists.rubyonrails.org/mailman/listinfo/rails >-------------- next part -------------- An HTML attachment was scrubbed... URL: http://wrath.rubyonrails.org/pipermail/rails/attachments/20060511/c7cd19de/attachment.html
Josh Susser
2006-May-11 15:55 UTC
[Rails] Re: Re: has_many :through scope on join attribute
Daniel ----- wrote:> Hi Josh, > > Thanx for the eplaination. I''ve been to your blog. I have found it > very > useful. Thanx. I have read your article that you mentioned but it must > of > been too late or something because I just couldn''t quite get my head > around > the relationships that you had. Also I don''t have the uniq option. I''m > assuming that this is only available for those on the edge.Right, :uniq is only on edge at the moment. However, for now you can still use the DISTINCT keyword in your :select if you need to remove duplicates. Did you manage to grok what I was doing in those associations? I''m moving the condition into the association in the join model, which from an object-oriented perspective is the right place to put it. You know, data-hiding and encapsulation and all that. If you''re curious what''s going on you should look at the generated SQL in development.log. -- Josh Susser http://blog.hasmanythrough.com -- Posted via http://www.ruby-forum.com/.
Hi Josh,
I can decipher what you have done but I don''t think that I understand
it
well enough to know when to use it yet. I''ll have a play with it.
Would there be a way to specify a validates_uniqueness_of :author
in your example to have only one author per book? Would something like
validates_uniqueness_of :author, :scope => ''book_id'', :if
Proc.new{
self.role = ''author'' }
make it so that there could only be one author per book?
On 5/12/06, Josh Susser <josh@hasmanythrough.com>
wrote:>
> Daniel ----- wrote:
> > Hi Josh,
> >
> > Thanx for the eplaination. I''ve been to your blog. I have
found it
> > very
> > useful. Thanx. I have read your article that you mentioned but it
must
> > of
> > been too late or something because I just couldn''t quite get
my head
> > around
> > the relationships that you had. Also I don''t have the uniq
option. I''m
> > assuming that this is only available for those on the edge.
>
> Right, :uniq is only on edge at the moment. However, for now you can
> still use the DISTINCT keyword in your :select if you need to remove
> duplicates.
>
> Did you manage to grok what I was doing in those associations? I''m
> moving the condition into the association in the join model, which from
> an object-oriented perspective is the right place to put it. You know,
> data-hiding and encapsulation and all that. If you''re curious
what''s
> going on you should look at the generated SQL in development.log.
>
> --
> Josh Susser
> http://blog.hasmanythrough.com
>
> --
> Posted via http://www.ruby-forum.com/.
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>
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Josh Susser
2006-May-12 23:59 UTC
[Rails] Re: Re: Re: has_many :through scope on join attribute
Daniel ----- wrote:> I can decipher what you have done but I don''t think that I understand it > well enough to know when to use it yet. I''ll have a play with it. > > Would there be a way to specify a validates_uniqueness_of :author > in your example to have only one author per book? Would something like > > validates_uniqueness_of :author, :scope => ''book_id'', :if Proc.new{ > self.role = ''author'' } > > make it so that there could only be one author per book?Yes, something like that validation should work, though you want == (not =) in the proc, and I think you''ll need to change :author to user_id. You might need to tweak something else, I haven''t built one of these before. -- Josh Susser http://blog.hasmanythrough.com -- Posted via http://www.ruby-forum.com/.