4.1Customizing the API

4 Running the Application

Now, if we run our app, we can try out the RESTful API that Grails has generated for us. Start up the app using a local installation of Grails 3.2.4 or one of the provided wrappers: ./gradlew bootRun or ./grailsw run-app

$ ./grailsw run-app

Now we can exercise the API using cURL or another API tool.

Make a GET request to /vehicle to get a list of Vehicles:

$ curl -X "GET" "http://localhost:8080/vehicle"

HTTP/1.1 200
X-Application-Context: application:development
Content-Type: application/json;charset=UTF-8
Transfer-Encoding: chunked
Date: Fri, 06 Jan 2017 19:28:49 GMT
Connection: close

[{"id":1,"driver":{"id":1},"make":{"id":1},"model":{"id":1},"name":"Pickup"},
{"id":2,"driver":{"id":1},"make":{"id":1},"model":{"id":2},"name":"Economy"},
{"id":3,"driver":{"id":2},"make":{"id":2},"model":{"id":3},"name":"Minivan"}]

Make a GET request to /driver/1 to get a particular Driver instance:

$ curl -X "GET" "http://localhost:8080/driver/1"

HTTP/1.1 200
X-Application-Context: application:development
Content-Type: application/json;charset=UTF-8
Transfer-Encoding: chunked
Date: Fri, 06 Jan 2017 22:10:33 GMT
Connection: close

{"id":1,"name":"Susan","vehicle":[{"id":2},{"id":1}]}

Make a POST request to /driver to create a new Driver instance:

$ curl -X "POST" "http://localhost:8080/driver" \
      -H "Content-Type: application/json; charset=utf-8" \
      -d '{"name":"Edward"}'

HTTP/1.1 201
X-Application-Context: application:development
Location: http://localhost:8080/driver/3
Content-Type: application/json;charset=UTF-8
Transfer-Encoding: chunked
Date: Fri, 06 Jan 2017 21:55:59 GMT
Connection: close

{"id":3,"name":"Edward"}

Make a PUT request to /vehicle to update a Vehicle instance:

$ curl -X "PUT" "http://localhost:8080/vehicle/1" \
       -H "Content-Type: application/json; charset=utf-8" \
       -d '{"name":"Truck","id":1}'

HTTP/1.1 200
X-Application-Context: application:development
Location: http://localhost:8080/vehicle/1
Content-Type: application/json;charset=UTF-8
Transfer-Encoding: chunked
Date: Fri, 06 Jan 2017 22:12:31 GMT
Connection: close

{"id":1,"driver":{"id":1},"make":{"id":1},"model":{"id":1},"name":"Truck"}

4.1 Customizing the API

By default, the RESTful URLs generated by Grails provide only the IDs of associated objects.

HTTP/1.1 200
X-Application-Context: application:development
Content-Type: application/json;charset=UTF-8
Transfer-Encoding: chunked
Date: Fri, 06 Jan 2017 23:55:33 GMT
Connection: close

{"id":1,"name":"Pickup","make":{"id":1},"driver":{"id":1}}

This is sufficient for many usages, but we’ll need to get a bit more data for our React component in a moment. This is an excellent place for JSON Views. Let’s create a new JSON view to render our Vehicle list:

$ mkdir grails-app/views/vehicle/

By convention, any JSON views in the corresponding view directory for a restful controller (like those generated by @Resource) will be used in lieu of the default JSON representation. Now we can customize our JSON output for each Vehicle by creating a new JSON template for Vehicle:

$ vim grails-app/views/vehicle/_vehicle.gson

Edit the file to include the following:

grails-app/views/vehicle/_vehicle.gson

import demo.Vehicle

model {
    Vehicle vehicle
}
json {
    id vehicle.id

    name vehicle.name

    make name: vehicle.make.name,
        id: vehicle.make.id

    model name: vehicle.model.name,
            id: vehicle.model.id

    driver name: vehicle.driver.name,
        id: vehicle.driver.id
}

Now when we access our API, we’ll see the name and id of each make, model, and driver are included.

HTTP/1.1 200
X-Application-Context: application:development
Content-Type: application/json;charset=UTF-8
Transfer-Encoding: chunked
Date: Sat, 07 Jan 2017 00:24:18 GMT
Connection: close

{"id":1,"name":"Pickup","make":{"name":"Nissan","id":1},"model":{"name":"Titan","id":1},"driver":{"name":"Susan","id":1}}

<< 3Writing the Application

5Writing our React components >>

Table of Contents

4 Running the Application

4.1 Customizing the API