Added a DSL to declare 'error_formatter' in API settings.

CHANGELOG.markdown

@@ -4,8 +4,9 @@
 * [#265](https://github.com/intridea/grape/issues/264): Fix: Moved `ValidationError` into `Grape::Exceptions` - [@thepumpkin1979](https://github.com/thepumpkin1979).
 * [#269](https://github.com/intridea/grape/pull/269): Fix: `LocalJumpError` will not be raised when using explict return in API methods - [@simulacre](https://github.com/simulacre).
 * [#86](https://github.com/intridea/grape/issues/275): Fix Path-based versioning not recognizing '/' route - [@walski](https://github.com/walski).
-* [#277](https://github.com/intridea/grape/pull/277): Added a DSL to declare `formatter` in API settings - [@tim-vandecasteele](https://github.com/tim-vandecasteele).
 * [#273](https://github.com/intridea/grape/pull/273): Disabled formatting via `serializable_hash` and added support for `format :serializable_hash` in API settings - [@dblock](https://github.com/dblock).
+* [#277](https://github.com/intridea/grape/pull/277): Added a DSL to declare `formatter` in API settings - [@tim-vandecasteele](https://github.com/tim-vandecasteele).
+* [#284](https://github.com/intridea/grape/pull/284): Added a DSL to declare `error_formatter` in API settings - [@dblock](https://github.com/dblock).
 * Your contribution here.
 
 0.2.2

README.markdown

@@ -501,6 +501,29 @@ class Twitter::API < Grape::API
 end
 ```
 
+Custom error formatters for existing and additional types can be defined with a proc.
+
+``` ruby
+class Twitter::API < Grape::API
+  error_formatter :txt, lambda { |message, backtrace, options| "error: #{message} from #{backtrace}" }
+end
+```
+
+You can also use a module or class.
+
+``` ruby
+module CustomFormatter
+  def self.call(message, backtrace, options)
+    { message: message, backtrace: backtrace }
+  end
+end
+
+class Twitter::API < Grape::API
+  error_format :custom
+  error_formatter :custom, CustomFormatter
+end
+```
+
 You can rescue all exceptions with a code block. The `rack_response` wrapper
 automatically sets the default error code and content-type.
 
@@ -589,7 +612,7 @@ Serialization takes place automatically.
 Your API can declare additional types to support. Response format is determined by the
 request's extension, an explicit `format` parameter in the query string, or `Accept` header.
 
-Custom formatters for additional types can be defined with a proc.
+Custom formatters for existing and additional types can be defined with a proc.
 
 ``` ruby
 class Twitter::API < Grape::API
@@ -613,7 +636,7 @@ class Twitter::API < Grape::API
 end
 ```
 
-You can also set the default format. Available formats are the following.
+You can set the default format. Available formats are the following.
 
 * `:json`: use object's `to_json` when available, otherwise call `MultiJson.dump`
 * `:xml`: use object's `to_xml` when available, usually via `MultiXml`, otherwise call `to_s`

lib/grape/api.rb

@@ -130,10 +130,15 @@ def format(new_format = nil)
         new_format ? set(:format, new_format.to_sym) : settings[:format]
       end
 
+      # Specify a custom formatter for a contnet-type.
       def formatter(content_type, new_formatter)
         settings.imbue(:formatters, content_type.to_sym => new_formatter)
       end
 
+      def error_formatter(format, new_formatter)
+        settings.imbue(:error_formatters, format.to_sym => new_formatter)
+      end
+
       # Specify the format for error messages.
       # May be `:json` or `:txt` (default).
       def error_format(new_format = nil)

lib/grape/endpoint.rb

@@ -378,6 +378,7 @@ def build_middleware
         :rescue_all => settings[:rescue_all],
         :rescued_errors => aggregate_setting(:rescued_errors),
         :format => settings[:error_format] || :txt,
+        :error_formatters => settings[:error_formatters],
         :rescue_options => settings[:rescue_options],
         :rescue_handlers => merged_setting(:rescue_handlers)
 

lib/grape/error_formatter/base.rb

@@ -11,14 +11,14 @@ class << self
         }
 
         def formatters(options)
-          FORMATTERS.merge(options[:formatters] || {})
+          FORMATTERS.merge(options[:error_formatters] || {})
         end
 
         def formatter_for(api_format, options = {})
           spec = formatters(options)[api_format]
           case spec
           when nil
-            lambda { |obj| obj }
+            lambda { |message, backtrace, options| message }
           when Symbol
             method(spec)
           else

lib/grape/middleware/error.rb

@@ -11,6 +11,7 @@ def default_options
         :default_message => "",
         :format => :txt,
         :formatters => {},
+        :error_formatters => {},
         :rescue_all => false, # true to rescue all exceptions
         :rescue_options => { :backtrace => false }, # true to display backtrace
         :rescue_handlers => {}, # rescue handler blocks
@@ -61,7 +62,7 @@ def rack_response(message, status = options[:default_status], headers = { 'Conte
       def format_message(message, backtrace, status)
         formatter = Grape::ErrorFormatter::Base.formatter_for(options[:format], options)
         throw :error, :status => 406, :message => "The requested format #{options[:format]} is not supported." unless formatter
-        formatter.send formatter.respond_to?(:encode) ? :encode : :call, message, backtrace, options
+        formatter.call(message, backtrace, options)
       end
 
     end

spec/grape/api_spec.rb

@@ -879,7 +879,7 @@ class CommunicationError < RuntimeError; end
       last_response.body.should eql "rain!"
     end
 
-    it 'should rescue all errros and return :txt with backtrace' do
+    it 'should rescue all errors and return :txt with backtrace' do
       subject.rescue_from :all, :backtrace => true
       subject.error_format :txt
       subject.get '/exception' do
@@ -889,6 +889,25 @@ class CommunicationError < RuntimeError; end
       last_response.body.start_with?("rain!\r\n").should be_true
     end
 
+    context "class" do
+      before :each do
+        class CustomErrorFormatter
+          def self.call(message, backtrace, options)
+            "message: #{message} @backtrace"
+          end
+        end
+      end
+      it 'should return a custom error format' do
+        subject.rescue_from :all, :backtrace => true
+        subject.error_formatter :txt, CustomErrorFormatter
+        subject.get '/exception' do
+          raise "rain!"
+        end
+        get '/exception'
+        last_response.body.should == "message: rain! @backtrace"
+      end
+    end
+
     it 'should rescue all errors and return :json' do
       subject.rescue_from :all
       subject.error_format :json
@@ -981,7 +1000,7 @@ class CommunicationError < RuntimeError; end
         last_response.body.should eql '{"custom_formatter":"hash"}'
       end
     end
-    context "custom formatter with a class" do
+    context "custom formatter class" do
       module CustomFormatter
         def self.call(object)
           "{\"custom_formatter\":\"#{object[:some]}\"}"

spec/grape/middleware/exception_spec.rb

@@ -109,8 +109,10 @@ def app
         use Grape::Middleware::Error,
           :rescue_all => true,
           :format => :custom,
-          :formatters => {
-            :custom => lambda { |message, backtrace, options| { :custom_formatter => message }.inspect }
+          :error_formatters => {
+            :custom => lambda { |message, backtrace, options| 
+              { :custom_formatter => message }.inspect 
+            }
           }
         run ExceptionApp
       end