Merge pull request #559 from alces-software/validation-errors-can-have-metadata

Validation errors can have metadata added to them

Author: lgebhardt

lib/jsonapi/exceptions.rb

@@ -355,10 +355,11 @@ def errors
     end
 
     class ValidationErrors < Error
-      attr_reader :error_messages, :resource_relationships
+      attr_reader :error_messages, :error_metadata, :resource_relationships
 
       def initialize(resource)
         @error_messages = resource.model_error_messages
+        @error_metadata = resource.validation_error_metadata
         @resource_relationships = resource.class._relationships.keys
         @key_formatter = JSONAPI.configuration.key_formatter
       end
@@ -380,7 +381,13 @@ def json_api_error(attr_key, message)
                            status: :unprocessable_entity,
                            title: message,
                            detail: "#{format_key(attr_key)} - #{message}",
-                           source: { pointer: pointer(attr_key) })
+                           source: { pointer: pointer(attr_key) },
+                           meta: metadata_for(attr_key, message))
+      end
+
+      def metadata_for(attr_key, message)
+        return if error_metadata.nil?
+        error_metadata[attr_key] ?  error_metadata[attr_key][message] : nil
       end
 
       def pointer(attr_or_relationship_name)

lib/jsonapi/resource.rb

@@ -120,6 +120,29 @@ def model_error_messages
       _model.errors.messages
     end
 
+    # Add metadata to validation error objects.
+    #
+    # Suppose `model_error_messages` returned the following error messages
+    # hash:
+    #
+    #   {password: ["too_short", "format"]}
+    #
+    # Then to add data to the validation error `validation_error_metadata`
+    # could return:
+    #
+    #   {
+    #     password: {
+    #       "too_short": {"minimum_length" => 6},
+    #       "format": {"requirement" => "must contain letters and numbers"}
+    #     }
+    #   }
+    #
+    # The specified metadata is then be merged into the validation error
+    # object.
+    def validation_error_metadata
+      {}
+    end
+
     # Override this to return resource level meta data
     # must return a hash, and if the hash is empty the meta section will not be serialized with the resource
     # meta keys will be not be formatted with the key formatter for the serializer by default. They can however use the