1.简介
随着 Mobile App 的增多，很多时候我们在做用 Rails 做 API Base 项目时，rails 自带的 C 和 V 层显得过于繁杂，grape 可以帮助我们快速的构建和 Rails 完美融合的 API 接口。

2.安装

#gemfile 添加：
gem 'grape', '~> 1.0.2' #当前稳定版本

app文件下创建api文件夹，相关接口都在这

#在config/application.rb 下添加
config.paths.add File.join('app', 'api'), glob: File.join('**', '*.rb')
config.autoload_paths += Dir[Rails.root.join('app', 'api', '*')]

3.编写相关接口（简单写了两种写法）

#app/api/test_api.rb
class TestAPI < Grape::API #需大写
  format :json
  get 'get_test' do
    {message: "Hello #{params[:name]} via get"}
  end
  post 'post_test' do
    {message: "Hello #{params[:name]} via post"}
  end
  resource :user do
    desc "Return a user."
    get :test  do
      @user = User.first
    end
  end
end

routes.rb:

mount TestAPI => '/'

分别执行：

#根据你运行端口号
$ curl localhost:3000/get_test?name=test  
#=> {"message":"Hello test via get"}
$ curl -d 'name=test'  localhost:3056/post_test 
#=>{"message":"Hello test via post"}
$ curl localhost:3000/user/test
#=> user的属性值{id:...}

也可以定义一个文件夹（例如app/api/twitter/api.rb）：

module Twitter
  class API < Grape::API
    version 'v1', using: :header, vendor: 'twitter'
    # version 'v1', using: :path
    format :json
    # prefix :api

    resource :grade_schools do
      desc 'Return grade_schools 20 records'
      get :index do
        GradeSchool.limit(20)
      end

      desc 'Return a grade_school.'
      params do
        requires :id, type: Integer, desc: 'GradeSchool id.'
      end
      route_param :id do
        get do
          GradeSchool.find(params[:id])
        end
      end

      desc 'Create a grade_school.'
      params do
        requires :grade_school, type: String, desc: 'grade_school paramters.'
      end
      post do
        GradeSchool.create!({ name: params[:name],
                              grade: params[:grade] })
      end

      desc 'Update a grade_school.'
      params do
        requires :id, type: String, desc: 'grade_school ID.'
        requires :grade, type: String, desc: 'Your grade_school.grade'
      end
      put ':id' do
        GradeSchool.find(params[:id]).update({grade: params[:grade]})
      end

      desc 'Delete a grade_school.'
      params do
        requires :id, type: String, desc: 'grade_school ID.'
      end
      delete ':id' do
        GradeSchool.find(params[:id]).destroy
      end
    end
  end
end

routes.rb

 mount Twitter::API => '/'

一套增删改查访问操作

相关链接：https://github.com/ruby-grape/grape