# Multiple habtm-join between tables **URL:** \ **Category:** Rails\ **Created:** [January 12, 2008, 12:53am UTC](https://www.ruby-forum.com/t/multiple-habtm-join-between-tables/125782 "2008-01-12T00:53:06Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![kaeptnhaddock](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/d26b3c/32.png) [@kaeptnhaddock](https://www.ruby-forum.com/u/kaeptnhaddock)\ **Post date:** [January 12, 2008, 12:53am UTC](https://www.ruby-forum.com/t/multiple-habtm-join-between-tables/125782/1 "2008-01-12T00:53:06Z")
I have a table with institutions and a table with projects with I would like to join twice with a habtm-relation. \*\*\*Model institution has\_and\_belongs\_to\_many :projects, :join\_table =\> “customerinstitutions” ## \*\*\*Model project has\_and\_belongs\_to\_many :institutions, :join\_table =\> “customerinstitutions” This works fine. However, I would also like to define a contractor-relationship between project and institution, so I was trying to redefine the relations like this: \*\*\*Model institution has\_and\_belongs\_to\_many :customerprojects, :class\_name =\> “project”, :join\_table =\> “customerinstitutions” has\_and\_belongs\_to\_many :contractorprojects, :class\_name =\> “project”, :join\_table =\> “contractorprojects” ## \*\*\*Model project has\_and\_belongs\_to\_many :customerinstitutions, :class\_name =\> “institution”, :join\_table =\> “customerinstitutions” has\_and\_belongs\_to\_many :contractorinstitutions, :class\_name =\> “institution”, :join\_table =\> “contractorinstitutions” When I now try to display a project with its customer-institutions, I get the following error: ## \*\*\*Error NoMethodError in ProjectsController#show undefined method `institutions' for # /usr/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/ attribute_methods.rb:205:in`method\_missing’ app/controllers/projects\_controller.rb:17:in `show’ Any ideas what I am doing wrong? I appreciate any help on this. ---
**Author:** ![kaeptnhaddock](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/d26b3c/32.png) [@kaeptnhaddock](https://www.ruby-forum.com/u/kaeptnhaddock)\ **Post date:** [January 12, 2008, 1:54am UTC](https://www.ruby-forum.com/t/multiple-habtm-join-between-tables/125782/2 "2008-01-12T01:54:31Z")
update: the error actually reads as follows: NameError in ProjectsController#show undefined local variable or method `institution’ for #\ RAILS\_ROOT: /home/christof/Dokumente/ror/v1 Application Trace | Framework Trace | Full Trace /usr/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active\_record/ base.rb:1532:in `method_missing' /usr/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/ base.rb:1750:in`compute\_type’ /usr/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active\_record/ reflection.rb:125:in `send' /usr/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/ reflection.rb:125:in`klass’ /usr/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active\_record/ associations/has\_and\_belongs\_to\_many\_association.rb:132:in `construct_sql' /usr/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/ associations/has_and_belongs_to_many_association.rb:6:in`initialize’ /usr/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active\_record/ associations.rb:1032:in `new' /usr/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/ associations.rb:1032:in`customerinstitutions’ app/controllers/projects\_controller.rb:17:in `show’ And it looks like the source of the trouble is this line in the CONTROLLER: @customerinstitutions = @project.customerinstitutions.find(:all, :order =\> “name”) What I don’t understand: why is rails looking for a method called “institution”? ---
**Author:** ![kaeptnhaddock](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/d26b3c/32.png) [@kaeptnhaddock](https://www.ruby-forum.com/u/kaeptnhaddock)\ **Post date:** [January 12, 2008, 1:55am UTC](https://www.ruby-forum.com/t/multiple-habtm-join-between-tables/125782/3 "2008-01-12T01:55:06Z")
On Jan 11, 3:52 pm, kaeptnhaddock [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > \*\*\*Error > NoMethodError in ProjectsController#show > undefined method `institutions' for # /usr/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/ attribute_methods.rb:205:in `method\_missing’ > app/controllers/projects\_controller.rb:17:in `show’ Project has customerinstitutions and contractorinstitutions, and #show is looking for institutions. ///ark ---
**Author:** ![kaeptnhaddock](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/d26b3c/32.png) [@kaeptnhaddock](https://www.ruby-forum.com/u/kaeptnhaddock)\ **Post date:** [January 12, 2008, 9:59am UTC](https://www.ruby-forum.com/t/multiple-habtm-join-between-tables/125782/4 "2008-01-12T09:59:04Z")
> Project has customerinstitutions and contractorinstitutions, and #show > is looking for institutions. But why? Didn’t I specify in the model as well as in the controller, that it should be looking for customerinstitutions? I think the model is fine, for at least I was able to use fixtures like this one to fill data into both the project-table and the join- table: \*\*\*fixture for project project\_one: name: someproject description: blahblah customerinstitutions: institution\_one contractorinstitutions: institution\_two However, if I remove this line from the controller/show, then the error doesn’t appear: @customerinstitutions = @project.customerinstitutions.find(:all, :order =\> “name”) ---
**Author:** ![kaeptnhaddock](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/d26b3c/32.png) [@kaeptnhaddock](https://www.ruby-forum.com/u/kaeptnhaddock)\ **Post date:** [January 14, 2008, 9:14pm UTC](https://www.ruby-forum.com/t/multiple-habtm-join-between-tables/125782/5 "2008-01-14T21:14:25Z")
On Jan 12, 12:58 am, kaeptnhaddock [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > But why? Didn’t I specify in the model as well as in the controller, > that it should be looking for customerinstitutions? Yep, I see what you mean, and I don’t have a clue what’s going on. I’d start stepping through that code in the debugger. ///ark