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Node.js Basics

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Getting the Response Body

5:17 with Reggie Williams

In this video, we'll get the body from the response using something called a Stream.

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Due to a recent change in the routing of our website the path as shown in the video is no longer working. You'll want to change the URL to be:

// Connect to the API URL 
https://teamtreehouse.com/profiles/csalgado.json

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    We need more than just a status code to complete our goal of getting a student's 0:00
    profile information. 0:03
    So we can retrieve their badge count and total number of JavaScript points. 0:05
    We can get more info from the body of the response. 0:09
    Let's go back to the docs. 0:13
    The response object is a data event that gets emitted when 0:14
    a piece of data like student data from an API comes in. 0:19
    Let's check out what happens when this event occurs in our code. 0:24
    We can add a handler for the data event and 0:28
    give it a console.dir statement to print out the response. 0:30
    In Node, we handle events using the on method. 0:34
    We pass the on method two arguments, an event to watch for and 0:38
    a callback function to run when that event occurs. 0:42
    Similar to addEventListener. 0:45
    In this case, the event to watch for is the data event. 0:48
    The data event occurs when data is received by our program. 0:51
    Passing around large amounts of data is best done with a certain type of data. 0:55
    Buffers. 1:00
    All data types like strings are useful for humans, machines use binary data or 1:04
    data in the forms of ones and zeros. 1:08
    Large amounts of binary data are called streams and can be stored using buffers. 1:11
    We'll add a console.dir statement to get a better idea of what buffers look like. 1:16
    When we run our code, something interesting should happen. 1:22
    So first watch for the data event on the response object. 1:33
    And we'll pass the data in to the callback function, 1:42
    console.dir(data); Back to 1:53
    the terminal, there's our buffers. 2:00
    Now, this data isn't really readable or useful for us in this format. 2:08
    But don't worry, we'll fix that. 2:13
    Because the data comes in piece by piece, we can define a variable to store 2:17
    the response and concatenate data to it until the stream is complete. 2:21
    I'll create a variable named body to store the response body and 2:30
    set it to an empty string for now. 2:33
    Inside this event handler, instead of printing out the response, 2:36
    Let's add the data. 2:43
    We know this data is in the form of a buffer. 2:53
    We'll want to convert that to a string, so that we can use it. 2:56
    How will we know when the request has ended? 3:04
    Along with the data event, there's also an end event that's emitted 3:09
    when there is no more data to be consumed from the stream. 3:13
    This tells us when all the data has been sent. 3:18
    And we can handle this event just like other events in our callback. 3:21
    So on the response object, we'll watch for the end event. 3:30
    And when this happens, we'll run a callback function, 3:36
    Print out the body object or the body string in this case, save. 3:47
    And our entire response body is returned. 4:01
    Now in this format, the data isn't super readable or usable. 4:04
    We'll fix that, we wanna make this string an object so it's easier to interact with. 4:10
    As an object, we can access only the properties we want. 4:16
    Converting a string to a data structure is called parsing. 4:19
    JSON is a native JavaScript object, so 4:23
    we can use one of its methods to parse our string. 4:25
    The JSON parse method takes a string and returns a JSON object. 4:28
    We'll run JSON.parse on our body, Save. 4:41
    Now try printing this out. 4:50
    Now our data is an object and it's much more readable. 5:00
    We get an array with all of Carlos's badges and point totals. 5:04
    In the next video we'll wrap up our project's main functionality and 5:10
    add the ability to search for different users. 5:14

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