Added support for on-demand loading of items in Select2. Fixes #5038.

web/pgadmin/browser/static/js/node.ui.js

@@ -93,6 +93,57 @@ define([
     );
   });
 
+  /* Define on demand loading of dropdown items.
+   * This also requires ajax option of select2 to be set.
+   * The trick is, ajax: {} will also work even if you're actually not
+   * using ajax.
+   */
+  $.fn.select2.amd.define('select2/onDemandDataAdapter', [
+    'select2/utils',
+    'select2/data/select',
+  ], function (Utils, SelectAdapter) {
+
+    function onDemandDataAdapter ($element, options) {
+      this.$element = $element;
+      this.options = options;
+    }
+    Utils.Extend(onDemandDataAdapter, SelectAdapter);
+    onDemandDataAdapter.prototype.query = function (params, callback) {
+      var data = [];
+      var self = this;
+      if (!params.page) {
+        params.page = 1;
+      }
+      var pageSize = 20;
+
+      var $options = this.$element.children();
+      $options.each(function () {
+        var $option = $(this);
+
+        if (!$option.is('option') && !$option.is('optgroup')) {
+          return;
+        }
+
+        var option = self.item($option);
+
+        var matches = self.matches(params, option);
+
+        if (matches !== null) {
+          data.push(matches);
+        }
+      });
+
+      callback({
+        results: data.slice((params.page - 1) * pageSize, params.page * pageSize),
+        pagination: {
+          more: data.length >= params.page * pageSize,
+        },
+      });
+    };
+
+    return onDemandDataAdapter;
+  });
+
   /*
    * NodeAjaxOptionsControl
    *   This control will fetch the options required to render the select