Mixing ActiveRecord find Conditions

I want to find records on a combination of created_on >= some date AND name IN some list of names.

For ">=" I'd have to use sql condition. For "IN" I'd have to use a hash of conditions where the key is :name and the value is the array of names.

Is there a way to combine the two?

From stackoverflow Thanatos

• You can use named scopes in rails 2.1 and above

  Class Test < ActiveRecord::Base
    named_scope :created_after_2005, :conditions => "created_on > 2005-01-01"
    named_scope :named_fred, :conditions => { :name => "fred"}
  end
  

  then you can do

  Test.created_after_2005.named_fred
  

  Or you can give named_scope a lambda allowing you to pass in arguments

  Class Test < ActiveRecord::Base
    named_scope :created_after, lambda {|date| :conditions => ["created_on > ?", date]}
    named_scope :named, lambda{|name| :conditions => { :name => name}}
  end
  

  then you can do

  Test.created_after(Time.now-1.year).named("fred")
  

  From Laurie Young

• For more on named_scopes see Ryan's announcement and the Railscast on named_scopes

  class Person < ActiveRecord::Base
    named_scope :registered, lambda { |time_ago| { :conditions => ['created_at > ?', time_ago] } }
    named_scope :with_names, lambda { |names| { :conditions => { :names => names } } }
  end
  

  If you are going to pass in variables to your scopes you have to use a lambda.

  From Sixty4Bit

• The named scopes already proposed are pretty fine. The clasic way to do it would be:

  names = ["dave", "jerry", "mike"]
  date = DateTime.now
  Person.find(:all, :conidtions => ["created_at > ? AND name IN ?", date, names])
  

  From Honza

• If you're using an older version Rails, Honza's query is close, but you need to add parentheses for the strings that get placed in the IN condition:

  Person.find(:all, :conditions => ["created_at > ? AND name IN (?)", date, names])
  

  Using IN can be a mixed bag: it's fastest for integers and slowest for a list of strings. If you find yourself using just one name, definitely use an equals operator:

  Person.find(:all, :conditions => ["created_at > ? AND name = ?", date, name])
  

  From Josh Schwartzman

• I think I'm either going to use simple AR finders or Searchgasm.

  From Thanatos

• The cool thing about named_scopes is that they work on collections too:

  class Post < ActiveRecord::Base
    named_scope :published, :conditions => {:status => 'published'}
  end
  
  @post = Post.published
  
  @posts = current_user.posts.published
  

  From ismaSan