discourse-data-explorer/assets/javascripts/discourse/components/param-field.js.es6

export default Ember.TextField.extend({
  value: function(key, value, previousValue) {
    if (arguments.length > 1) {
      this.get('params')[this.get('pname')] = value;
    }
    return this.get('params')[this.get('pname')];
  }.property()
});