JSON and UrlEncoded request middleware now encode body conditionally

These middleware now pay attention to "Content-Type" of the request.
Each will only encode the body if the content-type value matches.

When a body is present but no Content-Type, the middleware higher on
the stack will use its encoding.

This makes it possible to keep both middlewares on the stack and choose
encoding type by Content-Type switching.

lib/faraday/request/json.rb

@@ -1,9 +1,11 @@
 module Faraday
-  class Request::JSON < Faraday::Middleware
+  class Request::JSON < Request::UrlEncoded
+    self.mime_type = 'application/json'.freeze
+
     class << self
       attr_accessor :adapter
     end
-    
+
     # loads the JSON encoder either from yajl-ruby or activesupport
     begin
       begin
@@ -21,12 +23,9 @@ module Faraday
     end
 
     def call(env)
-      if data = env[:body]
-        env[:request_headers]['Content-Type'] = 'application/json'
-
-        unless data.respond_to?(:to_str)
-          env[:body] = self.class.adapter.encode data
-        end
+      match_content_type(env) do |data|
+        # encode with the first successfully loaded adapter
+        env[:body] = self.class.adapter.encode data
       end
       @app.call env
     end

lib/faraday/request/url_encoded.rb

@@ -1,14 +1,31 @@
 module Faraday
   class Request::UrlEncoded < Faraday::Middleware
-    def call(env)
-      if data = env[:body]
-        env[:request_headers]['Content-Type'] = 'application/x-www-form-urlencoded'
+    class << self
+      attr_accessor :mime_type
+    end
+    
+    self.mime_type = 'application/x-www-form-urlencoded'.freeze
 
-        unless data.respond_to?(:to_str)
-          env[:body] = Faraday::Utils.build_nested_query data
-        end
+    def call(env)
+      match_content_type(env) do |data|
+        env[:body] = Faraday::Utils.build_nested_query data
       end
       @app.call env
     end
+    
+    def match_content_type(env)
+      type = request_type(env)
+      
+      if env[:body] and (type.empty? or type == self.class.mime_type)
+        env[:request_headers]['Content-Type'] ||= self.class.mime_type
+        yield env[:body] unless env[:body].respond_to?(:to_str)
+      end
+    end
+    
+    def request_type(env)
+      type = env[:request_headers]['Content-Type'].to_s
+      type = type.split(';', 2).first if type.index(';')
+      type
+    end
   end
 end

test/request_middleware_test.rb

@@ -1,8 +1,10 @@
 require File.expand_path(File.join(File.dirname(__FILE__), 'helper'))
+require 'rack/utils'
 
 class RequestMiddlewareTest < Faraday::TestCase
   def setup
     @conn = Faraday.new do |b|
+      b.request :url_encoded
       b.request :json
       b.adapter :test do |stub|
         stub.post('/echo') do |env|
@@ -12,30 +14,47 @@ class RequestMiddlewareTest < Faraday::TestCase
       end
     end
   end
-  
+
   def test_does_nothing_without_payload
     response = @conn.post('/echo')
     assert_nil response.headers['Content-Type']
     assert response.body.empty?
   end
-  
-  def test_encodes_hash
-    response = @conn.post('/echo', { :fruit => %w[apples oranges] })
+
+  def test_ignores_custom_content_type
+    response = @conn.post('/echo', { :some => 'data' }, 'content-type' => 'application/x-foo')
+    assert_equal 'application/x-foo', response.headers['Content-Type']
+    assert_equal({ :some => 'data' }, response.body)
+  end
+
+  def test_json_encodes_hash
+    response = @conn.post('/echo', { :fruit => %w[apples oranges] }, 'content-type' => 'application/json')
     assert_equal 'application/json', response.headers['Content-Type']
     assert_equal '{"fruit":["apples","oranges"]}', response.body
   end
-  
-  def test_skips_encoding_for_strings
-    response = @conn.post('/echo', '{"a":"b"}')
+
+  def test_json_skips_encoding_for_strings
+    response = @conn.post('/echo', '{"a":"b"}', 'content-type' => 'application/json')
     assert_equal 'application/json', response.headers['Content-Type']
     assert_equal '{"a":"b"}', response.body
   end
-  
-  def test_url_encoded
-    @conn.builder.swap Faraday::Request::JSON, Faraday::Request::UrlEncoded
-    
+
+  def test_url_encoded_no_header
     response = @conn.post('/echo', { :fruit => %w[apples oranges] })
     assert_equal 'application/x-www-form-urlencoded', response.headers['Content-Type']
     assert_equal 'fruit[]=apples&fruit[]=oranges', response.body
   end
+
+  def test_url_encoded_with_header
+    response = @conn.post('/echo', {'a'=>123}, 'content-type' => 'application/x-www-form-urlencoded')
+    assert_equal 'application/x-www-form-urlencoded', response.headers['Content-Type']
+    assert_equal 'a=123', response.body
+  end
+
+  def test_url_encoded_nested
+    response = @conn.post('/echo', { :user => {:name => 'Mislav', :web => 'mislav.net'} })
+    assert_equal 'application/x-www-form-urlencoded', response.headers['Content-Type']
+    expected = { 'user' => {'name' => 'Mislav', 'web' => 'mislav.net'} }
+    assert_equal expected, Rack::Utils.parse_nested_query(response.body)
+  end
 end