add custom error formatter

.rubocop_todo.yml

@@ -1,20 +1,48 @@
-# This configuration was generated by `rubocop --auto-gen-config`
-# on 2015-01-13 18:47:14 -0500 using RuboCop version 0.28.0.
+# This configuration was generated by
+# `rubocop --auto-gen-config`
+# on 2017-10-09 10:22:52 -0500 using RuboCop version 0.41.2.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
 # versions of RuboCop, may require this file to be generated again.
 
-# Offense count: 25
-# Configuration parameters: AllowURI, URISchemes.
+# Offense count: 1
 Metrics/AbcSize:
-  Max: 20
+  Max: 18
 
-# Offense count: 7
+# Offense count: 1
+Metrics/CyclomaticComplexity:
+  Max: 9
+
+# Offense count: 1
+# Configuration parameters: AllowHeredoc, AllowURI, URISchemes.
+# URISchemes: http, https
+Metrics/LineLength:
+  Max: 87
+
+# Offense count: 1
+# Configuration parameters: CountComments.
+Metrics/MethodLength:
+  Max: 18
+
+# Offense count: 1
+Metrics/PerceivedComplexity:
+  Max: 11
+
+# Offense count: 5
 Style/Documentation:
-  Enabled: false
+  Exclude:
+    - 'spec/**/*'
+    - 'test/**/*'
+    - 'lib/grape-active_model_serializers/endpoint_extension.rb'
+    - 'lib/grape-active_model_serializers/error_formatter.rb'
+    - 'lib/grape-active_model_serializers/formatter.rb'
+    - 'lib/grape-active_model_serializers/options_builder.rb'
+    - 'lib/grape-active_model_serializers/serializer_resolver.rb'
 
 # Offense count: 2
-# Configuration parameters: Exclude.
+# Configuration parameters: ExpectMatchingDefinition, Regex, IgnoreExecutableScripts.
 Style/FileName:
-  Enabled: false
+  Exclude:
+    - 'lib/grape-active_model_serializers.rb'
+    - 'spec/grape-active_model_serializers_spec.rb'

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ### 1.5.2 (Next)
 
+* [#76](https://github.com/ruby-grape/grape-active_model_serializers/pull/76): Add custom error formatter - [@xn](https://github.com/xn).
 * Your contribution here.
 
 ### 1.5.1 (April 25, 2017)

Gemfile

@@ -2,7 +2,7 @@ source 'https://rubygems.org'
 
 gemspec
 
-case version = ENV['GRAPE_VERSION'] || '~> 0.10.0'
+case version = ENV['GRAPE_VERSION'] || '~> 1.0.0'
 when 'HEAD'
   gem 'grape', github: 'intridea/grape'
 else

grape-active_model_serializers.gemspec

@@ -18,6 +18,7 @@ Gem::Specification.new do |gem|
 
   gem.add_dependency 'grape', '>= 0.8.0'
   gem.add_dependency 'active_model_serializers', '>= 0.10.0'
+  gem.add_dependency 'multi_json', '~> 1.0'
 
   gem.add_development_dependency 'listen', '~> 3.0.7'
   gem.add_development_dependency 'rspec'

lib/grape-active_model_serializers.rb

@@ -1,6 +1,7 @@
 require 'active_model_serializers'
 require 'grape'
 require 'grape-active_model_serializers/endpoint_extension'
+require 'grape-active_model_serializers/error_formatter'
 require 'grape-active_model_serializers/formatter'
 require 'grape-active_model_serializers/serializer_resolver'
 require 'grape-active_model_serializers/options_builder'

lib/grape-active_model_serializers/error_formatter.rb

@@ -0,0 +1,56 @@
+module Grape
+  module ErrorFormatter
+    module ActiveModelSerializers
+      extend Base
+
+      class << self
+        def call(message, backtrace, options = {}, env = nil, original_exception = nil)
+          result = if respond_to? :present
+                     wrap_message(present(message, env))
+                   else
+                     wrap_message(message)
+                   end
+
+          rescue_options = options[:rescue_options] || {}
+          if rescue_options[:backtrace] && backtrace && !backtrace.empty?
+            result = result.merge(backtrace: backtrace)
+          end
+          if rescue_options[:original_exception] && original_exception
+            result = result
+                     .merge(original_exception: original_exception.inspect)
+          end
+          if ::Grape.const_defined? :Json
+            ::Grape::Json.dump(result)
+          else
+            ::MultiJson.dump(result)
+          end
+        end
+
+        private
+
+        def wrap_message(message)
+          if active_model?(message)
+            ::ActiveModelSerializers::SerializableResource.new(
+              message,
+              serializer: ActiveModel::Serializer::ErrorSerializer
+            ).as_json
+          elsif ok_to_pass_through?(message)
+            message
+          else
+            { error: message }
+          end
+        end
+
+        def active_model?(message)
+          message.respond_to?(:errors) &&
+            message.errors.is_a?(ActiveModel::Errors)
+        end
+
+        def ok_to_pass_through?(message)
+          message.is_a?(Exceptions::ValidationErrors) ||
+            message.is_a?(Hash)
+        end
+      end
+    end
+  end
+end

spec/grape-active_model_serializers/error_formatter_spec.rb

@@ -0,0 +1,81 @@
+require 'spec_helper'
+require 'grape-active_model_serializers/error_formatter'
+
+describe Grape::ErrorFormatter::ActiveModelSerializers do
+  subject { Grape::ErrorFormatter::ActiveModelSerializers }
+  let(:backtrace) { ['Line:1'] }
+  let(:options) { Hash.new }
+  let(:env) { { 'api.endpoint' => app.endpoints.first } }
+  let(:original_exception) { StandardError.new('oh noes!') }
+
+  let(:app) { Class.new(Grape::API) }
+
+  before do
+    ActiveModel::Serializer.config.adapter = :json_api
+    app.format :json
+    app.formatter :jsonapi, Grape::Formatter::ActiveModelSerializers
+    app.error_formatter :jsonapi, Grape::ErrorFormatter::ActiveModelSerializers
+
+    app.namespace('space') do |ns|
+      ns.get('/', root: false) do
+        error!(message)
+      end
+    end
+  end
+
+  describe '#call' do
+    context 'message is an activemodel' do
+      let(:message) {
+        class Foo
+          include ActiveModel::Model
+          attr_accessor :name
+          def initialize(attributes = {})
+            super
+            errors.add(:name, 'We don\'t like bears')
+          end
+        end
+        Foo.new(name: 'bar')
+      }
+      it 'formats the error' do
+        result = subject
+                 .call(message, backtrace, options, env, original_exception)
+        json_hash = JSON.parse(result)
+
+        expected_result = {
+          'errors' => [
+            {
+              'source' => {
+                'pointer' => '/data/attributes/name'
+              },
+              'detail' => 'We don\'t like bears'
+            }
+          ]
+        }
+
+        expect(json_hash == expected_result).to eq(true)
+      end
+    end
+
+    context 'message is hash like' do
+      let(:message) { { 'errors' => ['error'] } }
+      it 'passes the message through' do
+        result = subject
+                 .call(message, backtrace, options, env, original_exception)
+        json_hash = JSON.parse(result)
+
+        expect(json_hash == message).to eq(true)
+      end
+    end
+
+    context 'message is text' do
+      let(:message) { 'error' }
+      it 'wraps the error' do
+        result = subject
+                 .call(message, backtrace, options, env, original_exception)
+        json_hash = JSON.parse(result)
+
+        expect(json_hash == { 'error' => message }).to eq(true)
+      end
+    end
+  end
+end