Add JSON middleware (#1400)

docs/middleware/list.md

@@ -27,6 +27,8 @@ base64 representation.
 * [`Multipart`][multipart] converts a `Faraday::Request#body` hash of key/value pairs into a
 multipart form request.
 * [`UrlEncoded`][url_encoded] converts a `Faraday::Request#body` hash of key/value pairs into a url-encoded request body.
+* [`Json Request`][json-request] converts a `Faraday::Request#body` hash of key/value pairs into a JSON request body.
+* [`Json Response`][json-response] parses response body into a hash of key/value pairs.
 * [`Retry`][retry] automatically retries requests that fail due to intermittent client
 or server errors (such as network hiccups).
 * [`Instrumentation`][instrumentation] allows to instrument requests using different tools.
@@ -44,7 +46,9 @@ before returning it.
 [authentication]:       ./authentication
 [multipart]:            ./multipart
 [url_encoded]:          ./url-encoded
+[json-request]:         ./json-request
 [retry]:                ./retry
 [instrumentation]:      ./instrumentation
+[json-response]:         ./json-response
 [logger]:               ./logger
 [raise_error]:          ./raise-error

docs/middleware/request/instrumentation.md

@@ -5,8 +5,8 @@ permalink: /middleware/instrumentation
 hide: true
 prev_name: Retry Middleware
 prev_link: ./retry
-next_name: Logger Middleware
-next_link: ./logger
+next_name: JSON Response Middleware
+next_link: ./json-response
 top_name: Back to Middleware
 top_link: ./list
 ---

docs/middleware/request/json.md

@@ -0,0 +1,31 @@
+---
+layout: documentation
+title: "JSON Request Middleware"
+permalink: /middleware/json-request
+hide: true
+prev_name: UrlEncoded Middleware
+prev_link: ./url-encoded
+next_name: Retry Middleware
+next_link: ./retry
+top_name: Back to Middleware
+top_link: ./list
+---
+
+The `JSON` request middleware converts a `Faraday::Request#body` hash of key/value pairs into a JSON request body.
+The middleware also automatically sets the `Content-Type` header to `application/json`,
+processes only requests with matching Content-Type or those without a type and
+doesn't try to encode bodies that already are in string form.
+
+### Example Usage
+
+```ruby
+conn = Faraday.new(...) do |f|
+  f.request :json
+  ...
+end
+
+conn.post('/', { a: 1, b: 2 })
+# POST with
+# Content-Type: application/json
+# Body: {"a":1,"b":2}
+```

docs/middleware/request/url_encoded.md

@@ -5,8 +5,8 @@ permalink: /middleware/url-encoded
 hide: true
 prev_name: Multipart Middleware
 prev_link: ./multipart
-next_name: Retry Middleware
-next_link: ./retry
+next_name: JSON Request Middleware
+next_link: ./json-request
 top_name: Back to Middleware
 top_link: ./list
 ---

docs/middleware/response/json.md

@@ -0,0 +1,29 @@
+---
+layout: documentation
+title: "JSON Response Middleware"
+permalink: /middleware/json-response
+hide: true
+prev_name: Instrumentation Middleware
+prev_link: ./instrumentation
+next_name: Logger Middleware
+next_link: ./logger
+top_name: Back to Middleware
+top_link: ./list
+---
+
+The `JSON` response middleware parses response body into a hash of key/value pairs.
+The behaviour can be customized with the following options:
+* **parser_options:** options that will be sent to the JSON.parse method. Defaults to {}.
+* **content_type:** Single value or Array of response content-types that should be processed. Can be either strings or Regex. Defaults to `/\bjson$/`.
+* **preserve_raw:** If set to true, the original un-parsed response will be stored in the `response.env[:raw_body]` property. Defaults to `false`.
+
+### Example Usage
+
+```ruby
+conn = Faraday.new('http://httpbingo.org') do |f|
+  f.response :json, **options
+end
+
+conn.get('json').body
+# => {"slideshow"=>{"author"=>"Yours Truly", "date"=>"date of publication", "slides"=>[{"title"=>"Wake up to WonderWidgets!", "type"=>"all"}, {"items"=>["Why <em>WonderWidgets</em> are great", "Who <em>buys</em> WonderWidgets"], "title"=>"Overview", "type"=>"all"}], "title"=>"Sample Slide Show"}}
+```

docs/middleware/response/logger.md

@@ -3,8 +3,8 @@ layout: documentation
 title: "Logger Middleware"
 permalink: /middleware/logger
 hide: true
-prev_name: Instrumentation Middleware
-prev_link: ./instrumentation
+prev_name: JSON Response Middleware
+prev_link: ./json-response
 next_name: RaiseError Middleware
 next_link: ./raise-error
 top_name: Back to Middleware

lib/faraday.rb

@@ -57,6 +57,8 @@
 #   conn.get '/'
 #
 module Faraday
+  CONTENT_TYPE = 'Content-Type'
+
   class << self
     # The root path that Faraday is being loaded from.
     #

lib/faraday/request.rb

@@ -44,7 +44,8 @@ class Request < Struct.new(
                           :TokenAuthentication,
                           'token_authentication'
                         ],
-                        instrumentation: [:Instrumentation, 'instrumentation']
+                        instrumentation: [:Instrumentation, 'instrumentation'],
+                        json: [:Json, 'json']
 
     # @param request_method [String]
     # @yield [request] for block customization, if block given
@@ -138,11 +139,11 @@ def marshal_dump
     # @param serialised [Hash] the serialised object.
     def marshal_load(serialised)
       self.http_method = serialised[:http_method]
-      self.body        = serialised[:body]
-      self.headers     = serialised[:headers]
-      self.path        = serialised[:path]
-      self.params      = serialised[:params]
-      self.options     = serialised[:options]
+      self.body = serialised[:body]
+      self.headers = serialised[:headers]
+      self.path = serialised[:path]
+      self.params = serialised[:params]
+      self.options = serialised[:options]
     end
 
     # @return [Env] the Env for this Request

lib/faraday/request/json.rb

@@ -0,0 +1,55 @@
+# frozen_string_literal: true
+
+require 'json'
+
+module Faraday
+  class Request
+    # Request middleware that encodes the body as JSON.
+    #
+    # Processes only requests with matching Content-type or those without a type.
+    # If a request doesn't have a type but has a body, it sets the Content-type
+    # to JSON MIME-type.
+    #
+    # Doesn't try to encode bodies that already are in string form.
+    class Json < Middleware
+      MIME_TYPE = 'application/json'
+      MIME_TYPE_REGEX = %r{^application/(vnd\..+\+)?json$}.freeze
+
+      def on_request(env)
+        match_content_type(env) do |data|
+          env[:body] = encode(data)
+        end
+      end
+
+      private
+
+      def encode(data)
+        ::JSON.generate(data)
+      end
+
+      def match_content_type(env)
+        return unless process_request?(env)
+
+        env[:request_headers][CONTENT_TYPE] ||= MIME_TYPE
+        yield env[:body] unless env[:body].respond_to?(:to_str)
+      end
+
+      def process_request?(env)
+        type = request_type(env)
+        body?(env) && (type.empty? || type.match?(MIME_TYPE_REGEX))
+      end
+
+      def body?(env)
+        (body = env[:body]) && !(body.respond_to?(:to_str) && body.empty?)
+      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
+end
+
+Faraday::Request.register_middleware(json: Faraday::Request::Json)

lib/faraday/response.rb

@@ -22,7 +22,8 @@ def on_complete(env)
 
     register_middleware File.expand_path('response', __dir__),
                         raise_error: [:RaiseError, 'raise_error'],
-                        logger: [:Logger, 'logger']
+                        logger: [:Logger, 'logger'],
+                        json: [:Json, 'json']
 
     def initialize(env = nil)
       @env = Env.from(env) if env
@@ -42,6 +43,7 @@ def reason_phrase
     def headers
       finished? ? env.response_headers : {}
     end
+
     def_delegator :headers, :[]
 
     def body

lib/faraday/response/json.rb

@@ -0,0 +1,54 @@
+# frozen_string_literal: true
+
+require 'json'
+
+module Faraday
+  class Response
+    # Parse response bodies as JSON.
+    class Json < Middleware
+      def initialize(app = nil, options = {})
+        super(app)
+        @parser_options = options[:parser_options]
+        @content_types = Array(options[:content_type] || /\bjson$/)
+        @preserve_raw = options[:preserve_raw]
+      end
+
+      def on_complete(env)
+        process_response(env) if parse_response?(env)
+      end
+
+      private
+
+      def process_response(env)
+        env[:raw_body] = env[:body] if @preserve_raw
+        env[:body] = parse(env[:body])
+      rescue StandardError, SyntaxError => e
+        raise Faraday::ParsingError.new(e, env[:response])
+      end
+
+      def parse(body)
+        ::JSON.parse(body, @parser_options || {}) unless body.strip.empty?
+      end
+
+      def parse_response?(env)
+        process_response_type?(env) &&
+          env[:body].respond_to?(:to_str)
+      end
+
+      def process_response_type?(env)
+        type = response_type(env)
+        @content_types.empty? || @content_types.any? do |pattern|
+          pattern.is_a?(Regexp) ? type.match?(pattern) : type == pattern
+        end
+      end
+
+      def response_type(env)
+        type = env[:response_headers][CONTENT_TYPE].to_s
+        type = type.split(';', 2).first if type.index(';')
+        type
+      end
+    end
+  end
+end
+
+Faraday::Response.register_middleware(json: Faraday::Response::Json)

lib/faraday/response/logger.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require 'forwardable'
+require 'logger'
 require 'faraday/logging/formatter'
 
 module Faraday
@@ -11,10 +12,7 @@ class Response
     class Logger < Middleware
       def initialize(app, logger = nil, options = {})
         super(app)
-        logger ||= begin
-          require 'logger'
-          ::Logger.new($stdout)
-        end
+        logger ||= ::Logger.new($stdout)
         formatter_class = options.delete(:formatter) || Logging::Formatter
         @formatter = formatter_class.new(logger: logger, options: options)
         yield @formatter if block_given?