Adding first_or_create, first_or_create!, first_or_new and first_or_build to Active Record.

This let's you write things like:

    User.where(:first_name => "Scarlett").first_or_create!(:last_name => "Johansson", :hot => true)

Related to #2420.

2 files changed, 44 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index 374791deb1..2979ad1cb3 100644
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -442,6 +442,7 @@ module ActiveRecord #:nodoc:
 
     class << self # Class methods
       delegate :find, :first, :first!, :last, :last!, :all, :exists?, :any?, :many?, :to => :scoped
+      delegate :first_or_create, :first_or_create!, :first_or_new, :first_or_build, :to => :scoped
       delegate :destroy, :destroy_all, :delete, :delete_all, :update, :update_all, :to => :scoped
       delegate :find_each, :find_in_batches, :to => :scoped
       delegate :select, :group, :order, :except, :reorder, :limit, :offset, :joins, :where, :preload, :eager_load, :includes, :from, :lock, :readonly, :having, :create_with, :to => :scoped
diff --git a/activerecord/lib/active_record/relation.rb b/activerecord/lib/active_record/relation.rb
index 15fd1a58c8..461237c7ad 100644
--- a/activerecord/lib/active_record/relation.rb
+++ b/activerecord/lib/active_record/relation.rb
@@ -94,6 +94,49 @@ module ActiveRecord
       scoping { @klass.create!(*args, &block) }
     end
 
+    # Tries to load the first record; if it fails, then <tt>create</tt> is called with the same arguments as this method.
+    #
+    # Expects arguments in the same format as <tt>Base.create</tt>.
+    #
+    # ==== Examples
+    #   # Find the first user named Scarlett or create a new one.
+    #   User.where(:first_name => 'Scarlett').first_or_create(:last_name => 'Johansson')
+    #   # => <User id: 1, first_name: 'Scarlett', last_name: 'Johansson'>
+    #
+    #   # Find the first user named Scarlett or create one with a different last name.
+    #   # We already have one Scarlett, so she'll be returned.
+    #   User.where(:first_name => 'Scarlett').first_or_create do |user|
+    #     user.last_name = "O'Hara"
+    #   end
+    #   # => <User id: 1, first_name: 'Scarlett', last_name: 'Johansson'>
+    #
+    #   # Find the first user named Andy or create several at a time.
+    #   User.where(:first_name => 'Andy').first_or_create([{:last_name => 'García'}, {:last_name => 'Mejía'}])
+    #   # => [#<User id: 2, first_name: 'Andy', last_name: 'García'>,
+    #         #<User id: 3, first_name: 'Andy', last_name: 'Mejía'>]
+    #
+    #   # Find the first user with last name García or create several at a time.
+    #   User.where(:last_name => 'García').first_or_create([{:first_name => 'Jorge'}, {:first_name => 'Andy'}])
+    #   # => <User id: 2, first_name: 'Andy', last_name: 'García'>
+    def first_or_create(*args, &block)
+      first || create(*args, &block)
+    end
+
+    # Like <tt>first_or_create</tt> but calls <tt>create!</tt> so an exception is raised if the created record is invalid.
+    #
+    # Expects arguments in the same format as <tt>Base.create</tt>.
+    def first_or_create!(*args, &block)
+      first || create!(*args, &block)
+    end
+
+    # Like <tt>first_or_create</tt> but calls <tt>new</tt> instead of <tt>create</tt>.
+    #
+    # Expects arguments in the same format as <tt>Base.new</tt>.
+    def first_or_new(*args, &block)
+      first || new(*args, &block)
+    end
+    alias :first_or_build :first_or_new
+
     def respond_to?(method, include_private = false)
       arel.respond_to?(method, include_private)     ||
         Array.method_defined?(method)               ||