Undefined method name for nil when using custom has_many relationship

Question

I'm trying to create the simplest has_many relationship possible for one of my models. It's defined like that:

# i know it doesn't make much sense. I'm using such ridiculous 
# where case to keep things simple for now
has_many :jobs, -> { where(id: 1) }, class_name: SidekiqJob

However, when i' trying to call that relationship in anyway, for example with MyModel.last.jobs, rails throws:

NoMethodError: undefined method `name' for nil:NilClass
from /Volumes/HDD/Users/michal/.rvm/gems/ruby-2.1.1/gems/activerecord-4.0.3/lib/active_record/relation/merger.rb:141:in `block in filter_binds'

Has anyone have any idea on what is going wrong in here?

ruby 2.1.1
rails 4.0.3

edit:

Original association definition:

has_many :jobs, (obj) -> { where('jid LIKE ?', "#{obj.superjob_id}%") }, class_name: SidekiqJob

Where is `name` being called? I don't see it in the code you supplied, just in the error. — Wes Foster, Jul 04 '16 at 15:45
I think has_many only works with objects and not model. jobs method shall work on objects of your model — Vijay Meena, Jul 04 '16 at 15:46
@WesFoster it's not called anywhere. At least not by my code. — mbajur, Jul 04 '16 at 15:46
@VijayMeena you're obviously right, that was a mistake, typo fixed — mbajur, Jul 04 '16 at 15:48
Have you tried different column names inside where, and not id - will it work? What is the purpose of your condition for id here (I got it's simple stub, but what is your goal)? Just in case, relation like `has_many` has option such as `foreign_key` to specify column name of the child table to use for relation. — Pavel Bulanov, Jul 04 '16 at 17:56
The reason because I ask is that I opened Rails source code at the line that you gave - [here](https://github.com/rails/rails/blob/v4.0.3/activerecord/lib/active_record/relation/merger.rb#L141). The call is happening from [this](https://github.com/rails/rails/blob/v4.0.3/activerecord/lib/active_record/relation/merger.rb#L107) method. It might be that your where clause somehow gets eliminated (or eliminates) the where clause that joins two tables (by id column). — Pavel Bulanov, Jul 04 '16 at 17:58
@PavelBulanov i've edited my OP, added original where statement — mbajur, Jul 04 '16 at 21:36
Just in case, it seems that syntax for lamba is different (order of -> and obj), see [here](http://stackoverflow.com/questions/2462203/rails-has-many-with-dynamic-conditions) - should be `has_many :jobs, -> (obj) { ...}` — Pavel Bulanov, Jul 05 '16 at 08:17

SoAwesomeMan · Answer 1 · 2016-07-04T19:10:00.837

has_many :jobs, -> { where(id: 1) }, class_name: SidekiqJob

Without digging into the source to see if something like to_s is called on the class_name value, it appears the syntax is incorrect and would require quotation marks around the class name:

has_many :jobs, -> { where(id: 1) }, class_name: "SidekiqJob"

See RailsGuides here: http://guides.rubyonrails.org/association_basics.html#scopes-for-has-many-where

class Author < ApplicationRecord
  has_many :confirmed_books, -> { where "confirmed = 1" },
    class_name: "Book"
end

From 3_2_release_notes.md: https://github.com/rails/rails/blob/37b36842330b5db1996fda80e387eae3a5781db8/guides/source/3_2_release_notes.md

Allow the :class_name option for associations to take a symbol in addition to a string. This is to avoid confusing newbies, and to be consistent with the fact that other options like :foreign_key already allow a symbol or a string.
has_many :clients, :class_name => :Client # Note that the symbol need to be capitalized

nope, it was not that. I'm still getting the same error. – mbajur Jul 04 '16 at 21:31 — mbajur, Jul 04 '16 at 21:31

score 0 · Accepted Answer · edited May 23 '17 at 12:22

It turned out to be related to ruby/active_record versions. According to this thread: create with has_many through association gets NoMethodError (undefined method `name' for nil:NilClass)

What i've done to "fix" that was to change my ruby version to 2.1.10. Then, i got rid of such errors (cause they've been thrown in more places). Anyway, i am still not able to includes my relation defined as in the OP. It seems that it's not possible to includes relations using custom where statements.

Undefined method name for nil when using custom has_many relationship

edit:

2 Answers2

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