Associations in where

[kvaggelakos]

I want to find all objects that don't have an associated model. The problem however is that nobrainer does not see the associative model as an attribute when building where queries, which I guess makes sense. I am unsure how to solve this problem though. Any ideas/help would be great.

To give you an idea for what I am trying to do by example: Profile:

has_one :github, dependent: :destroy

Github:

belongs_to :profile, required: true

Now I am trying to execute something like this:

pry(main)> Profile.where(:github.undefined => true)
NoBrainer::Error::UnknownAttribute: `github' is not a valid attribute of Profile
from ~/.rvm/gems/ruby-2.1.3/gems/nobrainer-0.29.0/lib/no_brainer/document/attributes.rb:158:in `ensure_valid_key!'

[kvaggelakos]

bump

[nviennot]

Oops sorry i thought I had replied to this already.

So has_one is like a has_many. It has no data. So you cannot query it at a class level. You'll have to do something more evolved to do this

[nviennot]

For example, you might want to maintain a integer num_github on the profile model and query it.

[kvaggelakos]

Thanks for the reply @nviennot.

Is this due to limitations in how rethinkdb works or nobrainer? Having a separate field num_github for a has_one relation doesn't make much sense, also it's kind of duplicating data. If possible I rather skip this method.

Would it be possible to do a subquery like an sql where not in style to get all profiles that don't have githubs with nobrainer? Is there a way to run rethinkdb commands straight?

Thanks for this awesome lib and all help.

[nviennot]

Here's what you can do:

class Profile
  include NoBrainer::Document

  has_one :github

  virtual_field :has_github do |doc|
    Github.without_ordering.where(:profile_id => doc['id']).to_rql.is_empty.not
  end
end

Now you can do Profile.where(:has_github => true)... and the has_github value will be returned as a virtual attribute. Essentially, you are computing the "num_github" variable on the fly.

If you know a better way in SQL, or with ActiveRecord, let me know, I'd like to see if I can do like them.

[nviennot]

If you wanted all profiles that had a github, it's easy:

Profile.join(:github).each { ... }

But if you want the ones that don't have a github, you'll have to do the virtual attribute method I'm afraid.