Mel Mel - 1 year ago 73
Ruby Question

Rails 4 - chaining model associations to access associated methods

I have models for User, Profile and Organisation Request. The associations are:


has_one :profile, dependent: :destroy
has_one :organisation_request, through: :profile
accepts_nested_attributes_for :organisation_request


belongs_to :user
belongs_to :organisation

Organisation Request

belongs_to :profile
# belongs_to :user#, through: :profile
belongs_to :organisation

In my user model, I have a method called full_name (which I use to format the presentation of a user's name.

I'm trying to access that full_name method in my organisation_requests model.

I'm trying to do that by writing the following method in my organisation requests model:

def related_user_name

When I try to use this in my organisation requests index, like this:

<%= link_to orgReq.related_user_name, organisation_request.profile_path( %>

I get an error that says:

undefined method `user' for nil:NilClass

When I try to use this idea in the rails console, with:

o = OrganisationRequest.last

OrganisationRequest Load (0.4ms) SELECT "organisation_requests".* FROM "organisation_requests" ORDER BY "organisation_requests"."id" DESC LIMIT 1
=> #<OrganisationRequest id: 2, profile_id: 1, organisation_id: 1, created_at: "2016-08-01 22:48:52", updated_at: "2016-08-01 22:48:52">
2.3.0p0 :016 > o.profile.user.formal_name
Profile Load (0.5ms) SELECT "profiles".* FROM "profiles" WHERE "profiles"."id" = $1 LIMIT 1 [["id", 1]]
User Load (0.5ms) SELECT "users".* FROM "users" WHERE "users"."id" = $1 LIMIT 1 [["id", 1]]
=> " John Test"

The concept seems to work in the console?
Can anyone see where I've gone wrong?

Answer Source

have you checked all of your organisation requests have profile? may be this not best practice try use profile.try(:user).try(:full_name)

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