Model.where（…）.first属性不是nil，而是显示nil

Question

I'm playing with rails console:

a = Event.where("location_id IS NULL")
  Event Load (0.7ms)  SELECT "events".* FROM "events" WHERE (start_date >= '2015-02-20' OR end_date >= '2015-02-20') AND (location_id IS NULL)
 => #<ActiveRecord::Relation [#<Event id: 58, name: "BENNY GREB CLINIC w Hard Rock Cafe Warszawa", start_date: "2015-02-21", end_date: nil, location: "Hard Rock Cafe Warsaw,ul. Złota 59,Warsaw,Poland", logo_url: "https://fbcdn-sphotos-c-a.akamaihd.net/hphotos-ak-...", website: "", facebook: "https://www.facebook.com/events/535924839876600", created_at: "2015-02-19 17:38:29", updated_at: "2015-02-19 17:38:29", logo_file_file_name: nil, logo_file_content_type: nil, logo_file_file_size: nil, logo_file_updated_at: nil, location_id: nil>]> 

So location: "Hard Rock Cafe Warsaw,ul. Złota 59,Warsaw,Poland"

But when I do:

2.2.0 :002 > a.first.location

I get

 => nil 

Why?

Answer 1

You have a location attribute and a location association and rails is using the association. You need to rethink your database structure so they are named differently.

Answer 2

As per the first comment in the question:

You might be using an active record association:

has_one :location

or

belongs_to :location

Active record will give precedence to the relation over the model attribute.

Try adding:

has_one/belongs_to :location, as: 'related_location'

To the model in order to ensure location is always defining the attribute. And you will access to the related location (using the location_id ) using the aliased method.