是否可以在Rails 4的LEFT OUTER JOIN JOIN中添加条件？

Question

Given this structure:

class Account < ActiveRecord::Base
    has_many :users
    has_many :teams
    validates :name, presence: true
end

class User < ActiveRecord::Base
    belongs_to :account
    has_and_belongs_to_many :teams
    validates :name, presence: true
end

class Team < ActiveRecord::Base
    belongs_to :account
    has_and_belongs_to_many :users
    validates :name, presence: true
end

The objective is to obtain a list/array of all the team ids/names for an account, along with a flag indicating whether a given user belongs to the team or not.

In SQL I can get this result with something like:

SELECT teams.id, teams.name, 
     teams_users.team_id IS NOT NULL AS member FROM teams 
    LEFT OUTER JOIN teams_users ON 
        (teams.id = teams_users.team_id AND team_users.user_id = ?)
    WHERE teams.account_id = ?

Is there a Rails 4 / ActiveRecord way to get the same result? Every attempt I've made has pushed the teams_users.user_id = ? condition into the WHERE clause, which only returns a list of teams for which the user is a member, rather than all the teams associated with the account.

Answer 1

It should be possible with the string form of joins . Sanitize any user input before interpolating into the string.

Team.select(:id, :name).
  select("teams_users.team_id IS NOT NULL AS member FROM teams").
  joins("LEFT OUTER JOIN teams_users ON (teams.id = teams_users.team_id AND team_users.user_id = #{current_user.id})").
  where(account_id: account.id)