CODEWITHSUNDEEP
ruby-on-rails
Mush
Mush

Reputation: 57

Rails: Finding all Users whose relationship has a specified attribute

I have three models:

class User < ActiveRecord::Base
  has_many :rosterplayers
  has_many :rosters, -> { uniq } ,  :through => :rosterplayers
end

class Roster < ActiveRecord::Base
  has_many :rosterplayers
  has_many :users, -> { uniq }, through: :rosterplayers
end

class Rosterplayer < ActiveRecord::Base
  belongs_to :roster
  belongs_to :user
  validates :user_id, :uniqueness => { :scope => :roster_id }
end

The Rosterplayer table has three columns: user_id, roster_id, and pending (boolean)

Question: Given a roster, how would I retrieve all users that are currently pending?

Attempt: My first attempt was to loop through all the users in the roster:

@team.rosters[0].users.each do |u|
  Rosterplayer.find_by(roster_id: rosters[0].id, user_id: u.id, pending: true)
end

But I feel like there is a better way of doing it.

Upvotes: 3

Views: 628

Answers (1)

MrYoshiji
MrYoshiji

Reputation: 54882

You can achivete this by doing the following:

User.includes(:rosterplayers).where(rosterplayers: { pending: true })

This will return all User records having at least 1 rosterplayer having pending set to true.

Limit the query to a specific roster instance:

User.includes(:rosterplayers).where(rosterplayers: { pending: true, roster_id: your_roster_id })
# your_roster_id can actually be an array of IDs

Additional note: Be carefull with .joins and .includes:

# consider these models
Post 
  belongs_to :user
                #^^
User
  has_many :posts
               #^

# the `includes/joins` methods use the name defined in the model :
User.includes(:posts).where(posts: { title: 'Bobby Table' })
                  #^            ^
# but the `where` uses the pluralized version (table's name) : 
Post.includes(:user).where(users: { name: 'Bobby' })
                #^^^           ^

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