Code snippet to access a REST API and request JSON data

Abstract

This code snippet is a subset of Code snippet to make an HTTP call and request data. This code snippet accesses a REST API, requests for JSON data and returns parsed JSON data the response.

Logic

Import the HTTPBuilder and the request methods.
Access the REST API by creating a new HTTP instance.
Request the JSON data passing the method, the content type, and the request configuration closure to the request method.
Return the parsed JSON data from the response.

Snippet

import groovyx.net.http.HTTPBuilder
import static groovyx.net.http.Method.GET
import static groovyx.net.http.ContentType.JSON
 
// initialize a new builder and give a default URL
def http = new HTTPBuilder("<URL>")
 
http.request(GET,JSON) { req ->
 
  response.success = { resp, jsonData ->
    assert resp.status == 200
	
	return jsonData
  }
 
  // called only for a 404 (not found) status code:
  response."404" = { resp ->
    log.error ("Not found")
  }
}

Placeholders

Placeholder	Description	Example
`<URL`>	`URL`	`http://free.currencyconverterapi.com/api/v5/convert?q=EUR_USD&compact=y`
`<methodName>`	`Name of the request method`	`GET`
`<contentType>`	`Type of the content requested for`	`JSON`

Context

The outcome of the code snippet depends on the content type passed to the request method. You could use this code, for example, to get a specific currency conversion rate.

import groovyx.net.http.HTTPBuilder
import static groovyx.net.http.Method.GET
import static groovyx.net.http.ContentType.JSON
 
// initialize a new builder and give a default URL
def http = new HTTPBuilder("http://free.currencyconverterapi.com/api/v5/convert?q=EUR_USD&compact=y")
 
http.request(GET,JSON) { req ->
 
  response.success = { resp, jsonData ->
    assert resp.status == 200
    if(jsonData){
      return jsonData
    }
    else{
      log.warn("No data returned")
      return null
    }
  }
 
  // called only for a 404 (not found) status code:
  response."404" = { resp ->
    log.error ("Not found")
  }
}

Use cases

On creation of the issue, convert the entered "Bidding amount" from Euros to Dollars.

Reference

HTTPBuilder
Groovy Documentation