06 - JSON Response

In this module, we'll return the response as JSON instead of a simple string.

Overview

We now have a proper sequence and a response with some of the stored data, but what if we want to know when the data was stored? We have that in the information in the database, but at the moment it is not coming back in the response. How do we do that? Let's look.

The Code

Go into the testcontroller.js file and add the following method. Add it to the bottom of the file above the export statement.

/*********************
 * Route 6: Return response as JSON
 **********************/
router.post('/six', function (req, res) {
  var testData = req.body.testdata.item;
  TestModel
    .create({
      testdata: testData
    })
    .then(
      function message(testdata) {
        res.json({ //1
          testdata: testdata  //2
        });
      }
    );
});

Analysis

1. In our callback, rather than res.send(), we will invoke the .json() method. This will, of course, package our response as json.

2. The same object that was added to the database is now being sent back to the client and stored in a testdata property.

Testing

Let's use Postman to test this: 1. Make sure your server is running. 2. Open Postman. 3. Open a new request. 4. Change the dropdown to POST. 5. Enter the endpoint into the URL: http://localhost:3000/test/six. 6. Click on the body tab under the url input field. 7. Choose the raw radio button. 8. In the dropdown, choose JSON (application/json). 9. In the empty space add, a JSON object like the one below:

{
    "testdata":{
        "item":"step 6"
    }
}

1. Press send.

2. You should see the following:

   
3. Notice that the data in the response matches the data in the request, but we are also getting back a full JSON object from the database, including timestamp data.

4. You should also go to Postgres and make sure that the data is there and that the testdata column matches the request and response:

screenshot

Summary of the Flow

In this module, the following flow is happening:

1. We make a POST request with Postman.

2. body-parser breaks the request into JSON.

3. The router sends the request to the testcontroller.

4. The controller with the /six endpoint is called.

5. The req.body.testdata.item is captured in the testData variable.

6. We then use the Sequelize create() method to create the object to be sent to the DB.

7. The object is sent and Postgres stores it.

8. After the data is stored, we fire the then() method, which returns a Promise.

9. We call a method that takes in a parameter called testdata. It holds the data for the response.

10. The method sends the data back as JSON this time, and the response goes to Postman.