CODEWITHSUNDEEP
ruby-on-railsrubyruby-on-rails-4activerecordmodel
avinodra
avinodra

Reputation: 102

Multiple model error in Rails

I have an application that has three models: company, university and formation.

Relations between these three models are: 

class Company < ActiveRecord::Base
  has_many :formations, dependent: :destroy
end 

class University < ActiveRecord::Base
  has_many :formations, dependent: :destroy
end 

class Formation < ActiveRecord::Base
    #company
    belongs_to :company
    #universities
    belongs_to :university


    def company_name
      (company or university).try(:name)
    end

    def company_name=(name)
      company_or_university = University.where(name: name).first
      company_or_university ||= Company.where(name: name).first_or_create
      self.company = company_or_university
    end
end

So in this application I want to dropdown a list of universities and companies in the same field for formation form that is why I'm using this code in my formation form:

<% companies_or_universities = (Company.all.pluck(:name) + University.all.pluck(:name)).sort %>
<%= f.text_field :company_name, data: {autocomplete_source: companies_or_universities}, required: true, class: "form-control form-newjob" %>

this code works fine, but the problem is when I try to create a new formation and chose university name, I'm getting this error

Company(#-650866168) expected, got University(#-647908008)

for self.company = company_or_university. How can I resolve this problem?

Upvotes: 1

Views: 57

Answers (1)

dgilperez
dgilperez

Reputation: 10796

I think the error is quite explanatory: you cannot use a Company association to store a University, since the expected object is a Company.

I believe that you'll get the result you are looking for if you rewrite your setter like this:

class Formation < ActiveRecord::Base
  def company_name=(name)
    university_from_name = University.where(name: name).first

    if university_from_name
      self.university = university_from_name
      self.company = nil if persisted?
    else
      self.company = Company.where(name: name).first_or_create 
      self.university = nil if persisted?
    end
  end
end

As a side note, I think this implementation may be improved by using a polymorphic association instead of plain associations and custom setter and getter methods.

Upvotes: 1

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