CODEWITHSUNDEEP
ruby-on-railsactiverecord
steharro
steharro

Reputation: 1079

Using a scope with .last is returning an AssociationRelation in view

A Client has many Statuses. To get the latest status I'm using the following scope on Status.

scope :latest, -> { order(:created_at).last }

This works as expected in the Rails Console.

client = Client.last
client.statuses.latest
=> #<Status id:...
client.statuses.latest.stage
=> 1

However, it doesn't work as expected in the view. (This is part of a dynamic form where f.object is a Client object). 

<%= f.object.statuses.latest.inspect %>

This returns a Status object as expected: #<Status id:...

But if I now try to access an attribute on the object, <%= f.object.statuses.latest.stage %> I get the following error.

undefined method `stage' for #<ActiveRecord::AssociationRelation []>

Which has thrown me, because it should be a Status object. Adding to my confusion, if I try a nonexistent attribute, such as <%= f.object.statuses.latest.foobar %>, I get the following error.

undefined method `foobar' for #<Status:0x007ff615fcdb28>

Update

I tried setting a Client object as an instance variable in the controller to test, and it works as expected. This problem only seems to happen when accessing the Client through the form object.

Is this a bug or some kind on limitation? Anyway around it?

Update 2

Found a way to fix this.

<%= f.object.statuses.latest.stage unless f.object.statuses.latest.blank? %>

I don't understand why this works, because latest isn't blank and returns a stage, so if anyone can explain it would be appreciated.

Upvotes: 4

Views: 2655

Answers (1)

SomeDudeSomewhere
SomeDudeSomewhere

Reputation: 3940

Please note that All scope methods will return an ActiveRecord::Relation.

I would refactor your model like this to get around this and still get the same functionality. 

 class Status < ActiveRecord::Base
    ....
    scope :newest, -> { order(:created_at) }

    def self.latest
       Status.newest.first
    end
 end

And you should be able to just call

client = Client.last
client.statuses.latest

Upvotes: 3

Related Questions