表单中的HTTP排序变量

Question

given a form like the following

<form action="/page" method="POST>
    <input type="hidden" name="input" value="12" />
    <input type="hidden" name="input" value="24" />
</form>

Using Google Chrome 31.x and PHP 5.5, /page now has a $_POST variable for input of 24

This happens because when the $_POST array is created, The value is over written in the array. And the latter value is the value which is preserved.

Most browsers Ive tested this is the case, But Is there any HTTP spec / browser spec which says that form inputs should be sent in the order they are defined ? Or could an update in the future (or an old browser) send these updates in the reverse order for example ? or a random order ?

Edit:

to give more context, It will not be used like the above in all cases. only in a certain case.

The first form element is a SELECT box, But depending on the options chosen, Javascript will be able to change the value, Without changing the Select box value

Answer 1

Regardless of the order in which HTTP sends your two values, PHP can only have one value for $_POST['input'].

To solve this, use array notation:

<form action="/page" method="POST>
    <input type="hidden" name="input[]" value="12" />
    <input type="hidden" name="input[]" value="24" />
</form>

Now you'll have an array $_POST['input'] with both values.

To answer your question about the spec, see this page:

http://www.w3.org/TR/html401/interact/forms.html#h-17.13.4

See the bullets for the application/x-www-form-urlencoded default content type.

The control names/values are listed in the order they appear in the document. The name is separated from the value by '=' and name/value pairs are separated from each other by '&'.