discourse/app/assets/javascripts/discourse/controllers/request-group-membership-form.js.es6

import computed from 'ember-addons/ember-computed-decorators';
import { popupAjaxError } from 'discourse/lib/ajax-error';
import DiscourseURL from 'discourse/lib/url';
import ModalFunctionality from 'discourse/mixins/modal-functionality';

export default Ember.Controller.extend(ModalFunctionality, {
  loading: false,
  reason: Ember.computed.alias('model.membership_request_template'),

  @computed('model.name')
  title(groupName) {
    return I18n.t('groups.membership_request.title', { group_name: groupName });
  },

  @computed('loading', 'reason')
  disableSubmit(loading, reason) {
    return (loading || Ember.isEmpty(reason));
  },

  actions: {
    requestMember() {
      if (this.currentUser) {
        this.set('loading', true);

        this.get('model').requestMembership(this.get('reason')).then(result => {
          DiscourseURL.routeTo(result.relative_url);
        }).catch(popupAjaxError).finally(() => {
          this.set('loading', false);
        });
      } else {
        this._showLoginModal();
      }
    }
  }
});