Add build_from method

CHANGELOG.md

@@ -2,6 +2,7 @@
 ## HEAD
 
 * Add facebook user_info_path option to initializer.rb [#63](https://github.com/Sorcery/sorcery/pull/63)
+* Add new function: `build_from` (allows building a user instance from OAuth without saving) [#54](https://github.com/Sorcery/sorcery/pull/54)
 
 ## 0.11.0
 

lib/sorcery/controller/submodules/external.rb

@@ -187,6 +187,15 @@ def create_from(provider_name, &block)
             @user = user_class.create_from_provider(provider_name, @user_hash[:uid], attrs, &block)
           end
 
+          # follows the same patterns as create_from, but builds the user instead of creating
+          def build_from(provider_name, &block)
+            sorcery_fetch_user_hash provider_name
+            config = user_class.sorcery_config
+
+            attrs = user_attrs(@provider.user_info_mapping, @user_hash)
+            @user = user_class.build_from_provider(attrs, &block)
+          end
+
           def user_attrs(user_info_mapping, user_hash)
             attrs = {}
             user_info_mapping.each do |k, v|

lib/sorcery/model/submodules/external.rb

@@ -73,6 +73,21 @@ def create_from_provider(provider, uid, attrs)
             end
             user
           end
+
+          # NOTE: Should this build the authentication as well and return [user, auth]?
+          # Currently, users call this function for the user and call add_provider_to_user after saving
+          def build_from_provider(attrs)
+            user = new
+            attrs.each do |k, v|
+              user.send(:"#{k}=", v)
+            end
+
+            if block_given?
+              return false unless yield user
+            end
+
+            user
+          end
         end
 
         module InstanceMethods