Question

In a Rails app I’m setting up nested routes

resource Country do
  resource State
  resource City
  resource User
  resource Post
end

I now want to display users that have posted within a country at ../country/1/users

In the User controller I have:

def index 
  @user = User.includes(:posts, :city, :state, :country)
  @user = @users.where("states.country_id = ?", params[:country_id]) if params[:country_id]
  @active_users = @users.where('posts_count > ?', 0).ranked_scope
end

I’m, getting:

PG::Error: ERROR:  column reference "posts_count" is ambiguous
LINE 1: ...untry_id" WHERE (states.country_id = '1') AND (posts_co...

I’m not sure if this is because:

1. There is a posts_count column on User, City, State, Country models and the query does not know which on to use. If so, what is the correct syntax to specify the table?
2. I’m stringing together two where clauses incorrectly.
3. Something else….?

I’d appreciate any suggestions or ideas.

Answer 1

OK, I eventually got to the bottom of this. The following query was incorrect

@users = @users.where("states.country_id = ?", params[:country_id]) if params[:country_id]

Post belongs to User, and Post has one Country through State. Without a direct relationship in one direction between USer and Country, I modified the query to

@users = @users.where(id: Country.find(params[:country_id]).users.uniq if params[:country_id]

(and double checked all my model relationships were properly configured).

Works!

The error message was not very helpful in tracking this down though!