Ruby-on-rails – Rails .where vs .find

ruby-on-railsruby-on-rails-3

I've noticed that the Model.where method always returns an array even if there is only one result where as the Model.find method doesn't. Is there any reason for this? I thought Model.where was the preferred function since Rails 3.X.

Should I be using Model.find when I expect a single result and Model.where when I expect more than one result?

Best Solution

  • where returns an ActiveRecord::Relation (not an array, even though it behaves much like one), which is a collection of model objects. If nothing matches the conditions, it simply returns an empty relation.

  • find (and its related dynamic find_by_columnname methods) returns a single model object. If nothing is found, an ActiveRecord::RecordNotFound exception is raised (but not with the dynamic find_by_ methods).

    While find can return an Array of records—not a Relation—if given a list of IDs, using where is preferred since Rails 3. Many similar uses of find are now deprecated or gone entirely.

So yes, if you only want and expect a single object, using find is easier, as otherwise you must call Model.where.first.

Note that old-style hash options to find and many dynamic find_ methods are deprecated as of Rails 4.0 (see relevant release notes).