What does it mean http request body?

Question

Upon reading stuffs about POST and get methods here there is a statement like \" when used post method it uses HTTP request Body . What Does it mean \" HTTP request body\".?

Answer 1

The following html

:

  Name: 
   Check
  Upload file: 
  Send the file

will send this HTTP request (which is a type of HTTP message):

POST / HTTP/1.1
Host: localhost:8000
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:50.0) Gecko/20100101 Firefox/50.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Upgrade-Insecure-Requests: 1
Content-Type: multipart/form-data; boundary=---------------------------8721656041911415653955004498
Content-Length: 465

-----------------------------8721656041911415653955004498
Content-Disposition: form-data; name="myTextField"

Test
-----------------------------8721656041911415653955004498
Content-Disposition: form-data; name="myCheckBox"

on
-----------------------------8721656041911415653955004498
Content-Disposition: form-data; name="myFile"; filename="test.txt"
Content-Type: text/plain

Simple file.
-----------------------------8721656041911415653955004498--

Lines POST / HTTP/1.1 to Content-Length: 465 are the HTTP headers, whilst the rest -- following the empty line -- corresponds to the HTTP message body (also known as content).

So how do you access this data in the back-end/server-side?
Different server-languages (e.g. Go-lang, Node.js and PHP... etc) have different ways to parse the http body from a http post request. In Node.js it is common to use body-parser which is a parsing middleware function (see example below).

// Node.js
// OBSERVE THAT YOU NEED THE BODY-PARSER MIDDLEWARE IN ORDER TO DO THIS!
⋮
var data1 = req.body.myTextField;
var data2 = req.body.myCheckBox;
var data3 = req.body.myFile;
⋮

More information about bodies:

Bodies can be broadly divided into two categories:

1. Single-resource bodies, consisting of one single file, defined by the two headers: Content-Type and Content-Length.
2. Multiple-resource bodies, consisting of a multipart body, each containing a different bit of information. This is typically associated with HTML Forms.

Sources:

• MDN