Effective form processing using php - php

Question

I'm working on some project and I want to process requests from forms in several templates. The question is how is to invoke a proper function in the handling scrip. Although, I've been coding for a while, I still cant come up with anything better then using a variable in a hidden field:
if ($_POST['somehiddenfield'] == 1) {
some_function_1();//doesnt matter if its a function or a method
}
if ($_POST['somehiddenfield'] == 2) {
$mainclass->somemethod();
}
//goes on indefinitely
Also I want to keep everything in a single handler file, where my main class is invoked. So is there a more effective way than using if ... else?

Answer 1

I'd do the following:
still have a hidden field, but let it contain something like the form name
<input type="hidden" name="formName" value="post">
Then you can do something like that in the consuming php script:
<?php
// whatever class you use... this is just a simple dummy
class FormsProcessor {
public function post($params) {
echo "processing post form";
}
}
$formName = "post"; // would be $formName = filter_input(INPUT_POST, $_POST['formName'],FILTER_SANITIZE_STRING,FILTER_FLAG_STRIP_HIGH);
// BUT BE SURE TO SANITIZE THE INPUT!!!
$params = []; // dummy
$formsProcessor = new FormsProcessor();
// here's the trick.
$formsProcessor->{$formName}($params);
// to be even safer you could check first if this method_exists()
// and/or if it's in a list of allowed methods.
Be aware that there mustn't be any other methods in this class that the user shouldn't invoke. You could go around that by really compose the method name of two parts:
$methodName = $formName."Processor";
//....
$formsProcessor->{$methodName}();`

Answer 2

I would keep a key=>value array hardcoded with all the possible options. Pass the hidden input field, check if there are any intersections between your post values and the keys of the hardcoded options and call any matching values as functions.
$map = [
'yourHiddenField' => 'myFunctionName',
'anotherHiddenField' => 'myOtherFunctionName',
'yourOtherHiddenField' => 'yetAnotherfunctionName',
];
$intersection = array_intersect(array_keys($map), array_keys($_POST));
foreach ($intersection as $key) {
$this->{$map[$key])();
}
This code hasn't been tested.
EDIT:
Be careful with allowing ANY input to be ran without predefining which functions you should allow to be ran.
Example of how dangerous it could be even with sanitisation:
class Test {
public $i = 1;
function __construct(){
$this->i++;
}
}
$formVariable = '__construct';
$t = new Test();
$t->{$formVariable}();
echo $t->i;