select2.js

gistfile1.js

up.compiler(".django-select2", function(element) {
    var $modal = $(".up-modal-content");
    var options = {};

    if ($modal.length > 0) {
        // https://select2.org/troubleshooting/common-problems
        options.dropdownParent = $modal;
        options.width = "100%";
    }

    $(element).djangoSelect2(options);

    $(element).on('select2:select', function (e) {
        if (element.form.method.toLowerCase() === "get") {
            up.submit(element.form);
        }
    });

    return function() {
        $(element).select2("destroy");
    }
});