CODEWITHSUNDEEP
ruby-on-railsruby-on-rails-3activerecord
Peter Klipfel
Peter Klipfel

Reputation: 5178

Rails Get Nested Relationship as ActiveRecord object without collect/map

As an example:

A company has_many employees

an employee has_many tasks

I want to get all the tasks in descending order. Ideally, I'd like to do something like Company.all.employees.tasks.order('created_at desc'). Unfortunately, by the time I get through employees, I now have an array of ActiveRecord objects. I've been running into this issue for a while, and I've just been using map and collect, but sorting in descending order makes for more overhead than I want. This can be done with a SQL query so I'm sure I can do it in ActiveRecord, but my research hasn't helped much.

EDIT: The solution should work for any number of models. For example, if a task has_many items and an item has_many sub_items ad infinitum.

Upvotes: 3

Views: 2305

Answers (1)

Rob Di Marco
Rob Di Marco

Reputation: 44952

One approach you can use is to use through

class Company < ActiveRecord::Base
   has_many :employees
   has_many :tasks, through: :employees
end

Then a Company will have tasks for all of it's employees. c Another way to do it would be to use joins. So assuming that a Task belongs_to a Employee and an Employee belongs_to a Company

c = Company.first # for a company...
tasks = Task.where(companies:{id: c.id}).joins(employee: :company)

So I am asking for all tasks where the companies table (and yes it is the table in the where). We use the joins to establish the tables that must be joined to.

Upvotes: 5

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