What are the precise rules/PHP function for encoding strings into POST arrays?

Question

Just getting into PHP web development. I've got an HTML form where a user checks some series of dynamically-generated checkboxes, and submits via POST. On the PHP side, I want to check which of the check-boxes were clicked.

I have an array $full_list, and am doing something like

$selected_checkboxes = array_filter($full_list, function($item) {
    array_key_exists($item, $_POST);
  }

I run into problems when a list item is named, for example "Peanut Butter", since in the POST array it is named "Peanut_Butter".

I could certainly just str_replace " " with "_" before checking array_key_exists, but I imagine that there is a more fundamental encoding problem here; specifically, I'm not sure of exactly what layer transforms normal strings in HTML Forms (value="Peanut Butter") into "Peanut_Butter".

So:

what layer is responsible for this conversion? Is it the browser?
what are the exact conversion rules, and is there a PHP function out there that will replicate that exact conversion?

Community · Accepted Answer · 2017-05-23 12:15:53Z

3

The accepted answer by Byron Whitlock is wrong. PHP is indeed the culprit here. See the PHP manual:

Dots and spaces in variable names are converted to underscores. For example <input name="a.b" /> becomes $_REQUEST["a_b"].

Also refer to the answers of this similar question.

edited May 23, 2017 at 12:15

CommunityBot

11 silver badge

answered Aug 9, 2015 at 23:22

le_m

20.4k10 gold badges70 silver badges78 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Byron Whitlock · Accepted Answer · 2010-05-26 22:22:26Z

-1

PHP doesn't do this. There is something on the client side that is converting spaces to underscores.

The browser should encode each variable using the equivalent of urlencode(). PHP will automatically decode these strings so it is transparent for the programmer.

edit The equivalent in javaScript is escape(). But it is very very likely there is some js code manually converting spaces to underscores.

edited May 26, 2010 at 22:22

answered May 26, 2010 at 22:12

Byron Whitlock

54.2k29 gold badges129 silver badges170 bronze badges

6 Comments

AlexeyMK Over a year ago

Thanks. Would a urlencode be sufficient to replicate whatever happens on the client code, then?

Byron Whitlock Over a year ago

You can just use firebug or fiddler. create a simpel <form><input name=bleh></form> and then put in some text. Look on the net panel in firebug to see what the browser sends. If you aren using firefox, grab fiddler and do the same thing. I promise though, you have some javascript rewriting your strings.

AlexeyMK Over a year ago

I'm sure I do, and I'll look at that. I'm more interested, though, in what function on the PHP server side replicates whatever browsers are doing. Also, am I approaching this problem the wrong way? I can't be the first to need to check which of a series of form checkboxes have been clicked.

AlexeyMK Over a year ago

Looking at escape - it doesn't convert spaces to underscores, but to %20's. This is what's confusing me :)

le_m Over a year ago

it would be nice if this incorrect but accepted answer could be fixed to prevent spreading misinformation.

|

Collectives™ on Stack Overflow

What are the precise rules/PHP function for encoding strings into POST arrays?

2 Answers 2

Comments

6 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

6 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related