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The Request Object

4:29 with Andrew Chalkley and Joel Kraft

A closer look at Express's Request object.

HTML Forms

Documentation

What body-parser Does Under the Hood

What is body-parser doing? In case you're curious, here's a little code that reads the body of an incoming request and logs it to the console. This is just a flavor of how using body-parser is making your life easier!

  let bodyString = ''
  req.on('data', chunk => bodyString += chunk.toString());
  req.on('end', () => {
    console.log(bodyString);
  });

Note that even after bodyString has been read completely, it still needs to be turned from a string into data your application can use, all of which is taken care of by body-parser.

  • 0:00

    Remember when we wrote out first route by hand and had to use a request and

  • 0:05

    response object for the route handler.

  • 0:08

    We've been using the response object to return a response to the client.

  • 0:12

    But we haven't been using the request object yet, apart from declaring it.

  • 0:18

    Let's look at the express documentation for the request object.

  • 0:22

    There are quite a few properties that you can access on the request.

  • 0:28

    The one we're most interested in is the body property.

  • 0:33

    This is where our form response will end up.

  • 0:36

    Notice though, that by default it is undefined.

  • 0:41

    To put the form responses into the body, we'll need what is called Middleware.

  • 0:47

    Middleware is basically some code that fits in the middle of a request or

  • 0:51

    a response.

  • 0:53

    Middleware does something to the incoming data and

  • 0:56

    hands the result of to the rest of your application.

  • 1:00

    We'll look more deeply at Middleware later in this course.

  • 1:04

    But we don't really need to know a lot about it yet.

  • 1:06

    I will show you how to install some middleware in a moment.

  • 1:10

    First, though,

  • 1:11

    let's use the console to take a look at the request object more closely.

  • 1:16

    In the app.js file,

  • 1:19

    I'll add a line in the post route to print out the request object to the console.

  • 1:25

    I'll save it and then go back to the browser to create a new request.

  • 1:31

    Our code will run.

  • 1:34

    I don't need a name right now, and I'll click on Submit.

  • 1:39

    Moving to the console where Express is running,

  • 1:41

    you can see that the request object includes a lot of information.

  • 1:46

    We will look too closely at the request.

  • 1:48

    I just wanted you to get an appreciation for

  • 1:51

    the amount of work expressed as to simplify our job as developers.

  • 1:56

    Most of the time, we don't need many of these properties.

  • 1:58

    We'll just access a select few.

  • 2:02

    I'll clear this screen, and then we'll switch back to the app.js file.

  • 2:06

    I'm just going to examine the body property now.

  • 2:11

    If I submit the form now using my name And switch to the console,

  • 2:19

    as you can see, I get undefined, just as the documents promised.

  • 2:25

    Let's install the middleware, called for by the docs.

  • 2:30

    It's called body parser and it will process the incoming form submission data

  • 2:34

    into a format that's easier for our program to read.

  • 2:39

    I'll go to the terminal and then I'll type,

  • 2:45

    npm install body-parser.

  • 2:51

    When that's done, I can require it in my app.js file at the top.

  • 3:09

    Now, we'll tell Express to use it.

  • 3:12

    Body-parser contains several parses, the different ways the clients can send data.

  • 3:19

    HTML forms normally encode the data they send the same way URLs do.

  • 3:25

    So, we'll need to use the urlencode parser.

  • 3:32

    We'll pass in an object, turning

  • 3:37

    off the parser's extended option.

  • 3:46

    Don´t worry too much about this line of code.

  • 3:49

    To be honest,

  • 3:50

    I have to look this up everytime I need to include it in my Express applications.

  • 3:56

    I've included more information about how forms and data and

  • 3:59

    how body-parser works in the teacher's notes.

  • 4:03

    Now, let's submit a name.

  • 4:06

    In the console, you can see the body property has now a username property.

  • 4:14

    Our app is now able to understand the information it's getting from our form.

  • 4:19

    Next, we'll use that information to send something meaningful back to the client.

  • 4:24

    While we do this, let's take a closer look at the response objects in the next video.

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