12 Tips of Christmas - 10 Building API's with GrapeAs I work more and more with Ember, grasping onto well structured API's becomes increasingly valuable. Thanks to Grape, building an API out of your Rails application is very easy.
To start, add grape to your Gemfile, like so and run
As we're ultimately serving up a response to requests from the client, we're going to house our API in our controllers directory. As Grape supports versioned API's we're going to keep that structure in place when we begin to create our API. So, first things first, let's create a
base.rbfile to mount our versioned API's
Now let's create our other
# app/controllers/api/base.rb module API class Base < Grape::API mount API::V1::Base end end
base.rbfile in our V1 directory so we can mount the resources this version of the API will support.
Let's also setup our routes to support our new API
# app/controllers/api/v1/base.rb module API class Base < Grape::API mount API::V1::Users mount API::V1::Posts end end
This makes our users and posts API available at http://localhost:3000/api/v1/users.json and http://localhost:3000/api/v1/posts.json respectively (assuming you're exporting out JSON).
# config/routes.rb mount API::Base => '/api'
So let's take a look at what our API's might look like:
In this very simple example, we declare the version and the format in which we will return.
module API module V1 class Posts < Grape::API version 'v1' format :json resource :posts do desc "Return 10 most recent posts" get do Post.most_recent.limit(10) end desc 'Find a specific post' params do requires :id, type: Integer, desc: "The ID of the post" end get ':id' do Post.find(params[:id) end end end end end
We also declare the resource we're going to work with, along with our two
GETrequests we accept, one that returns the 10 most recent posts and one that will return a post determined by the id parameter supplied.
You'll notice that this is starting to look alot like our regular controllers, as well it should. We can also expand on this to start allowing users to make
PATCHrequests as well.
With our params block , we can specify what parameters we accept as well as in what format they should come, much like Rails' strong parameters.
We also have the ability to document our API as we go with our description methods, this is far far easier to do as you're building up the API so I highly encourage you to do it as you go.
In the next post we'll take a look at restricting the data coming back out of our API
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