Multipart/form-data

HTML & CSS
1

Hi

When uploading a file using HTML, we use the following method in the form tag

multipart/form-data

I know we use it when uploading file but I want to know what does it do? Why cannot we upload a file without this method?

Thanks

2

Because that’s how the HTTP protocol says we do it :slight_smile: It’s called “multipart” because the HTTP request has “multiple parts” – one for the main request body, one for the form data, one for each binary object, separated by multipart boundaries.

RFC 1867: Form-Based File Upload in HTML

Hypertext Transfer Protocol – HTTP/1.1

3

http://www.faqs.org/rfcs/rfc2388.html

4

The default encoding type, application/x-www-form-urlencoded, lists field names and values similar to how they appear in the query parameters in a GET request. For instance,

POST /form.php HTTP/1.1
Host: www.example.com

name=Jane&age=42&skills=html,css

As you can see, this type of encoding is not useful for uploading files, because files can contain any character.

With a multipart/form-data encoding the POST request body is split into multiple parts. Each part is delimited by a special identifier string, which makes it possible for the receiving application to detect the end of the uploaded file’s content.

5

Now that is what I call an “answer” :slight_smile:

many thanks AutisticCuckoo, your 2 minute effort helped me understand the concept and saved an hour of mine from reading a 3 page confusing article.

Thanks again

6

Glad I could help! :slight_smile: