WP_REST_Request::set_param() ignores parameter order.

[TimothyBlynJacobs]

WP_Rest_Request::get_param() traverses through the parameter order but WP_Rest_Request::set_param() does not. For JSON requests, this means that changing a parameter with set_param() will have no affect on get_param().

Example Code:

$request = new WP_REST_Request();
$request->add_header( 'content-type', 'application/json' );
$request->set_method( 'POST' );
$request->set_body( wp_json_encode( [
	'param' => 'hi'
] ) );

echo $request->get_param( 'param' ); // hi
$request->set_param( 'param', 'hello' );
echo $request->get_param( 'param' ); // hi

Patch incoming.

[rmccue]

Good catch! I didn't get to this previously, but good to go for 4.8, because it's a bugfix.

Patch looks good, but I'd rather avoid using reset(), since it modifies the array. We know $order is an indexed array, so $first = $order[0] is fine.

[TimothyBlynJacobs]

Great, thanks! Should I upload another patch?

[jnylen0]

Use [0] instead of reset; whitespace fixes; use array() instead of []

[jnylen0]

@TimothyBlynJacobs in general, yes, if a patch has known issues then it is always useful to have a refreshed version on the ticket.

40344.2.diff​ addresses the following issues:

• Use [0] instead of reset to get the first element of the array
• Core (including unit tests) cannot use [ 'key' => 'value' ] array syntax; we still support PHP 5.2
• Trailing whitespace on blank lines

Patch LGTM as well. I'll commit when tests pass locally.

[TimothyBlynJacobs]

Awesome, thanks @jnylen0!

[jnylen0]

In 40815:

REST API: Fix changing parameters with set_param() for some requests.

Prior to this commit, WP_Rest_Request::get_param() traversed through the parameter order but WP_Rest_Request::set_param() did not. For JSON requests (and likely other situations as well), this meant that changing a parameter with set_param() would have no effect on get_param().

Props TimothyBlynJacobs.
Fixes #40344.