I need to create a custom formfield like so:


But the data I want to populate the list with is in a json file. So I can't really do a PHP for each, or if I do, I need to somehow do a JS for each at the same time.

Any advice you can provide to steer me, even to resources would be appreciated.

  • 2
    In your code for the custom field can you not just read the json string in from the file and use the php function json_decode to get an associative array which is easy to work with? May 27, 2020 at 20:33
  • You can mark that as the answer @RobbieJackson that was enough to help me on my way. Thanks a million.
    – Eoin
    Jun 13, 2020 at 14:53
  • 1
    Glad it worked ok. I'll leave it to you to include the solution if you like, and mark it correct, as I think you're probably better placed to explain the details. That would be useful to help anyone else who had the same issue. Jun 13, 2020 at 21:03

1 Answer 1


Here was the final answer which was placed in mod_modulename/models/fields/stackexchangesites.php

// Check to ensure this file is included in Joomla!
defined('_JEXEC') or die('Restricted access');

// load the list class

// The class name must always be the same as the filename (in camel case).  
// Extend the list class
class JFormFieldStackexchangesites extends JFormFieldList

    //The field class must know its own type through the variable $type.
    protected $type = 'Stackexchangesites';

    // declare the function to get options
    public function getOptions()

        // assign JSON to a variable
        $json = '{"items":[{"aliases":["http://www.stackoverflow.com","http://facebook.stackoverflow.com"],.....~';

        // decode the JSON, and set it as an associative array
        $sites = json_decode($json, true);

        // set the value of i so we can iterate over it
        $i = 0;

        // run a foreach on our JSON to get the values for our options
        foreach($sites['items'] as $site)
            // find the api_site_parameter
            $stackExchangesSitesOptions[] = $site['api_site_parameter'];

            // iterate our i

        // Merge any additional options in the XML definition.
        $options = array_merge(parent::getOptions(), $stackExchangesSitesOptions);
        return $options;

Finally, in my XML

        <fields name="params">
            // add field path so it knows where to look
            <fieldset name="basic" addfieldpath="/modules/mod_kou_stack_exchange/models/fields">
                // include your field
                        label="Stackexchange Sites"

All the field does is create a dropdown with a list of all the stackexchange sites. The final output of the module loads questions from a stack exchange site based on the user.

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