OmarQureshi.net

Using "or" in Mongoid

17 Jun 2010

Document Databases, Rails, Ruby, Mongoid, MongoDB, and Javascript

Not a very well documented feature here, but, if anyone wants to use something similar to an SQL OR query in MongoDB (using Mongoid) there are two ways, depending on the complexity of the query and the version of Mongo that you have.

Firstly, there is the very easy $in example, represented by saying

scope :in_array, lambda {|arr| where(:in => arr)}

Which is great for the really simple examples – however, for something more substantial, what you’ll need to do is write custom javascript to get what you want

scope :date_constraint, lambda {
  today = Date.today
  js_date = "new Date(#{today.year}, #{today.month}, #{today.day})"
  where("function() {return this.end_date == null || this.end_date >= #{js_date}}")
}

Which is probably not the nicest way of writing such a query, but, its more like a limitation of the Database query language more than a fault with the Mongoid API (which is based on Arel/ActiveModel and fantastic!)