How to dynamically add wordpress shortcodes

Question

I'm working on a plugin where the user can build a form and then display that form on the front end using a shortcode name of their choice.

In the database I have a list of form names, and the necessary data to render them, but I can't figure out how to dynamically register the shortcode function.

Below is some psudeo code that shows what I want to do. In it I query my database and pull out an object which contains the name of the form and a some json strings which I can parse and use to call a premade function with parameters:

foreach ($dbQuery as $row){
  function $row->formName(){ // I know I can't do this
    $internalFunction = json_decode($row->json)->internalFunctionName; // dynamically refrence predefined function
    $internalFunction(json_decode($row->json)->params); // call the function defined above
    // do other things with the string from the database
  }
  add_shortcode( $row->formName, $row->formName );
}

I looked up if php supports dynamic function names, and I found this SO post which says it only supports dynamic closures. I tried using them but wordpress throws an error saying the shortcode doesn't have a proper callback function. So I think it wants a real function.

I also found a similar question on this site, but didn't see how this would let me define my own code in the function.

Any help would be much appreciated!

Answer 1

Assuming the $row->internalFunction is a function, or the name of a function which already exists, then you can do something like so:

foreach ( $dbQuery as $row ) {
    add_shortcode( $row->formName, $row->internalFunction );
}

So if the formName (shortcode tag) is foo and internalFunction is foo_func, then [foo] will be handled by the foo_func() function:

// The standard/non-dynamic way.
function foo_func( $atts = array() ) {
    return 'something good..';
}
add_shortcode( 'foo', 'foo_func' );

See the Codex for further details/guide.

---

Or here's an example of using closure:

foreach ( $dbQuery as $row ) {
    $func = $row->internalFunction;
    add_shortcode( $row->formName, function ( $atts = array() ) use ( $func ){
        return $func( $atts );
    } );
}

---

Or did I misunderstand your concept?

UPDATE

is there a way I can pass parameters into the internal function

Yes, you can pass custom parameters to the internal function (internalFunction); but you'll do it via the closure:

foreach ( $dbQuery as $row ) {
    $func = $row->internalFunction;
    $params = json_decode( $row->json )->params;
    add_shortcode( $row->formName, function ( $atts = array() ) use ( $func, $params ){
        return $func( $params );
    } );
}

Basically, use the use keyword to make variables in the foreach scope be available in the closure.

And you could even pass the entire $row object..

foreach ( $dbQuery as $row ) {
    add_shortcode( $row->formName, function ( $atts = array() ) use ( $row ){
        $func = $row->internalFunction;
        // Here you can pass $row->formName to the function.
        return $func( json_decode( $row->json )->params );
    } );
}