Question

I am having great difficulty reading the API for named scopes. Each ‘bid’ has a user_id and an auction_id. I need a scope to return the auctions the user has bid on.

Auction

class Auction < ActiveRecord::Base    has_many :bids    named_scope :current, lambda {      {:conditions => ['scheduled_start < ?', 0.minutes.ago],                        :order => 'scheduled_start asc'}    }    named_scope :scheduled, lambda {      {:conditions => ['scheduled_start > ?', 0.minutes.ago],                        :order => 'scheduled_start asc'}    }  end 

Bid

class Bid < ActiveRecord::Base   belongs_to :user   belongs_to :auction    validates_numericality_of :point, :on => :create   #  # how do I write a named scope to check if a user has bid on an auction?  end 

Answer 1

you might wanna try a has many through association instead of a named scope.

class User < ActiveRecord::Base   has_many :bids   has_many :auctions, :through => :bids end 

Or do it the other way round

class Auction < ActiveRecord::Base   has_many :bids   has_many :users, :through => :bids end 

That way, you can simply write: @auction.users.include?(user)

That is not very clear to read, so lets improve it:

class Auction < ActiveRecord::Base   has_many :bids   has_many :bidders, :through => :bids, :source => :user end 

And now: @auction.bidders.include?(user)

Lastly, you can pass more than one param to a lamda, so (not the best example)

named_scope :for_apple_and_banana, lambda{|apple_id, banana_id| {:conditions => ['apple_id = ? AND banana_id = ?', apple_id, banana_id ]}}