Added an example that preprocesses params sent as JSON data.

Author: dblock

README.md

@@ -10,6 +10,7 @@ A [Grape](http://github.com/ruby-grape/grape) API mounted on Rack.
 * [ping](api/ping.rb): a hello world example that returns a JSON document
 * [post_put](api/post_put.rb): a simple `POST` and `PUT` example
 * [post_json](api/post_json.rb): an example that shows a `POST` of JSON data
+* [get_json](api/get_json.rb): an example that pre-processes params sent as JSON data
 * [rescue_from](api/rescue_from.rb): an example of `rescue_from` that wraps all exceptions in an HTTP error code 500
 * [path_versioning](api/path_versioning.rb): an example that uses path-based versioning
 * [header_versioning](api/header_versioning.rb): an example that uses vendor header-based versioning

api/get_json.rb

@@ -0,0 +1,24 @@
+module Acme
+  class GetJson < Grape::API
+    format :json
+    desc 'Flips reticulated in a collection of splines passed as JSON in a query string.'
+    resource :reticulated_splines do
+      before do
+        params.each_pair do |k, v|
+          params[k] = JSON.parse(v) rescue v
+        end
+      end
+      params do
+        requires :splines, type: Array do
+          requires :id, type: Integer
+          requires :reticulated, type: Boolean
+        end
+      end
+      get do
+        params[:splines].map do |spline|
+          spline.merge(reticulated: !spline[:reticulated])
+        end
+      end
+    end
+  end
+end

app/api.rb

@@ -9,6 +9,7 @@ class API < Grape::API
     mount ::Acme::PostPut
     mount ::Acme::WrapResponse
     mount ::Acme::PostJson
+    mount ::Acme::GetJson
     mount ::Acme::ContentType
     mount ::Acme::UploadFile
     mount ::Acme::Entities::API

spec/api/get_json_spec.rb

@@ -0,0 +1,21 @@
+require 'spec_helper'
+
+describe Acme::API do
+  include Rack::Test::Methods
+
+  def app
+    Acme::API
+  end
+
+  it 'flips reticulated in a collection of splines' do
+    get '/api/reticulated_splines', 'splines' => [
+      { id: 1, reticulated: false },
+      { id: 2, reticulated: true }
+    ].to_json
+    expect(last_response.status).to eq(200)
+    expect(last_response.body).to eq([
+      { id: 1, reticulated: true },
+      { id: 2, reticulated: false }
+    ].to_json)
+  end
+end