Question

How do I create a nested form for 2 scaffolded models?

I have a Syllabus model, which has many Missions. Previously, the only way to create Missions was through the Syllabus nested form (which I made with Railscasts). Yesterday, I decided that users should be able to create Missions by itself, so I scaffolded the Missions while skipping the migrations, so it created all the controllers and views for the existing Missions Model.

So here’s the problem: I can now create Missions by itself, but when I try to create Missions through the Syllabus nested form, it gives me an error “undefined method `difficulty’ for #<\Mission:0xb372ffc.>” I’m guessing it’s trying to pass in the Syllabus attributes to the Missions attribute, which isn’t defined in the Missions schema. (difficulty is an attribute only for Syllabus).

To sum up: Nested forms worked with “builder” when I only had Model for Missions, but when I scaffolded the Missions so it could exist by itself, I couldn’t use the nested form.

Because there were more than a couple files that may affect this, I created a gist.
https://gist.github.com/2631734

Btw, these are the params that should be passed in

{"utf8"=>"✓",
"authenticity_token"=>"YxkzNmIJl0jBA467tdHP2zqNv22DgKrzSx+WCFgwKtk=",
"syllabus"=>
    {"category"=>"Technology and Internet",
    "difficulty"=>"Beginner",
    "title"=>"missions testing",
    "description"=>"deccrip",
    "missions_attributes"=>
        {"0"=>
            {"_destroy"=>"false",
            "title"=>"plz",
            "content"=>"<p>\r\n\tdad</p>\r\n"
            }
        }
    },
    "commit"=>"Create Syllabus"
}

Answer 1

I figured it out, but it is really messy… I’m sure there’s a better way to do it, but after struggling with this for a few days, I’m more than happy with this solution:

  @syllabus = Syllabus.new(:title => params[:syllabus][:title], :category => params[:syllabus][:category], :difficulty => params[:syllabus][:difficulty], :description => params[:syllabus][:description], :author_id => current_user)

  @syllabus.save!

  params[:syllabus][:missions_attributes].each do |a, b|

    @mission = Mission.new(:title => b[:title], :content => b[:content], :syllabus_id => @syllabus.id, :author_id => current_user, :category => @syllabus.category)

    @mission.save!

    end