CODEWITHSUNDEEP
ruby-on-railspolymorphic-associations
Confused in California
Confused in California

Reputation: 23

Rails 3 polymorphic association raising a NameError

I have the following 2 models:

class FuzzyDate < ActiveRecord::Base
  belongs_to :fuzzy_dateable, :polymorphic => true
end

class Device < ActiveRecord::Base
  has_one :received_date, :as => :fuzzy_dateable
end

with the following schema:

  create_table "devices", :force => true do |t|
    t.string   "meid"
    t.datetime "created_at"
    t.datetime "updated_at"
  end

  create_table "fuzzy_dates", :force => true do |t|
    t.date     "date"
    t.integer  "fuzz"
    t.integer  "fuzzy_dateable_id"
    t.string   "fuzzy_dateable_type"
    t.datetime "created_at"
    t.datetime "updated_at"
  end

Let's fire up the console, shall we?

>> d = Device.create(:meid => "A")
=> #<Device id: 1, meid: "A", created_at: "2010-12-16 06:52:55", updated_at: "2010-12-16 06:52:55">
>> fd = FuzzyDate.create(:date => Date.today, :fuzz => 3)
=> #<FuzzyDate id: 1, date: "2010-12-15", fuzz: 3, fuzzy_dateable_id: nil, fuzzy_dateable_type: nil, created_at: "2010-12-16 06:53:04", updated_at: "2010-12-16 06:53:04">
>> fd.fuzzy_dateable = d
=> #<Device id: 1, meid: "A", created_at: "2010-12-16 06:52:55", updated_at: "2010-12-16 06:52:55">
>> fd
=> #<FuzzyDate id: 1, date: "2010-12-15", fuzz: 3, fuzzy_dateable_id: 1, fuzzy_dateable_type: "Device", created_at: "2010-12-16 06:53:04", updated_at: "2010-12-16 06:53:04">

Ok, so far, so good. Let's go from the other direction:

>> d.received_date
NameError: uninitialized constant Device::ReceivedDate
        from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.3/lib/active_record/base.rb:1199:in `compute_type'
        from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.3/lib/active_record/reflection.rb:162:in `send'
        from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.3/lib/active_record/reflection.rb:162:in `klass'
        from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.3/lib/active_record/reflection.rb:198:in `quoted_table_name'
        from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.3/lib/active_record/associations/has_one_association.rb:97:in `construct_sql'
        from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.3/lib/active_record/associations/has_one_association.rb:7:in `initialize'
        from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.3/lib/active_record/associations.rb:1450:in `new'
        from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.3/lib/active_record/associations.rb:1450:in `received_date'
        from (irb):5
>>

Doh! I've done a bunch of Googleing, and the answers I found are all along the lines of incorrectly using plural model names, which is not the case here. I've spent a couple evenings banging my head against this, so any guidance would be greatly appreciated.

Upvotes: 2

Views: 1759

Answers (1)

DanneManne
DanneManne

Reputation: 21180

The problem here is that in your Device model, you name the association :received_date and that will by default look for a ReceivedDate model unless you tell it otherwise.

I'd say you can choose from either one of these solutions.

No. 1

class Device < ActiveRecord::Base
  has_one :received_date, :as => :fuzzy_dateable, :class_name => "FuzzyDate"
end

No. 2

class Device < ActiveRecord::Base
  has_one :fuzzy_date, :as => :fuzzy_dateable
end

Upvotes: 7

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