How to validate a form when the submit button is outside of this form, with angularJs?

Question

I have a form element created with AngularJS with a submit button within it and I would like to put this button outside of this form. How can I do that with Angular and have my form still validated?

e.g main html code:

<div class="sd-chk-steps" ng-show="!step_03" ng-hide="step_03">

<!-- Panel Address -->
<div id="sd-p-chk-1" class="large-8 columns sd-p-chk">
  <div class="cover step_complete" ng-show="step_01" ng-hide="!step_01">
  </div>
  <sd-panel-address >
  <!-- first form -->
  </sd-panel-address>
</div>
<!-- /. Panel Address -->

<!-- Panel delivery -->
<div id="sd-p-chk-2" class="large-8 columns sd-p-chk">
  <div class="cover" ng-show="!step_01" ng-hide="step_01"></div>
  <sd-panel-delivery>
  <!-- second form -->
  </sd-panel-delivery>
  <div class="cover step_complete" ng-show="step_02" ng-hide="!step_02"></div>
</div>
<!-- /. Panel delivery  -->

<!-- Panel payment -->
<div id="sd-p-chk-3" class="large-8 columns sd-p-chk">
  <div class="cover" ng-show="!step_02" ng-hide="step_02"></div>
  <sd-panel-payment>
  <!-- third form -->
  </sd-panel-payment>
</div>
<!-- /. Panel payment -->

<!-- group botton submit -->
<div class="sd-chk-box">
    <div class="sd-chk-box-inner">

        <div class="large-8 columns sd-box-chk-btn sd-chk-btn-sm">
          <button ng-click="clickBtn(shipping.$valid)" type="submit" class="sd-chk-btn sd-button-cta" ng-disabled="shipping.$invalid">
            Next
          </button>
        </div>

        <div class="large-8 columns sd-box-chk-btn sd-chk-btn-sm">
          <button class="sd-chk-btn sd-button-cta" ng-click="clickBtnStep02(formDelivery.$valid)" ng-disabled="formDelivery.$invalid">
            NEXT
          </button>
        </div>

        <div class="large-8 columns sd-box-chk-btn sd-chk-btn-sm">
          <button class="sd-chk-btn sd-button-cta" ng-click="clickBtnStep03(payment.$valid)" ng-disabled="payment.$invalid">
            PLACE ORDER
          </button>
        </div>

    </div>
</div>
<!-- /. group botton submit -->

e.g form html code:

<form id="shipping" class="shipping" name="shipping" 
      novalidate
      ng-submit="form.submit(shipping.$valid)"
      ng-class="{'loading': form.submitting, 'is-el-dirty' : shipping.$dirty || shipping.dirty}">
      <fieldset>
        <div class="row">
          <div class="large-12 columns">
            <label>
              <input type="text" name="name" placeholder="Name" ng-model="form.data.name" required/>
            </label>
            <div class="error" ng-if="shipping.$submitted || shipping.name.$touched" ng-messages="shipping.name.$error">
                <p class="text-msg" ng-message="required">You did not enter your name</p>
            </div>
          </div>
          <div class="large-12 columns">
            <label>
              <input type="text" name="surname" placeholder="Surname" ng-model="form.data.surname" required/>
            </label>
            <div class="error" ng-if="shipping.$submitted || shipping.surname.$touched" ng-messages="shipping.surname.$error">
                <p class="text-msg" ng-message="required">You did not enter your Surname</p>
            </div>
          </div>
        </div>
      </fieldset>
</form>

e.g controller code:

(function() {

  'use strict';

  /**
   * @ngdoc function
   * @name myApp.controller:globalCtrl
   * @description
   * # globalCtrl
   * Controller of the myApp
   */

  var myApp = angular.module('myApp');


  myApp.controller('globalCtrl', function($scope, $locale, $rootScope) {

      // Check if checkbox it's checked
      $scope.checked = true;

      // got to step 2
      $scope.clickBtn = function(form) {
          //valid form
          if (form === true) {
              console.log('Form is valid, $rootScope.step_01= ' + $rootScope.step_01);
              $rootScope.step_01 = true;
              $rootScope.notValidStpe_01 = true;
          }

          //invalid form
          if (form === false) {
              $rootScope.step_01 = false;
              $rootScope.notValidStpe_01 = false;
              console.log('Form is invalid, $rootScope.step_01= ' + $rootScope.step_01);
          }
      };

      // got to step 3
      $scope.clickBtnStep02 = function(form) {
          //valid form
          if (form === true) {
              console.log('Form is valid, $rootScope.step_02 "'+ $rootScope.step_02);
              $rootScope.step_02 = true;
              $rootScope.notValidStpe_02 = true;

          }

          //invalid form
          if (form === false) {
              $rootScope.step_02 = false;
              $rootScope.notValidStpe_02 = false;
              console.log('Form is invalid, $rootScope.step_02= ' + $rootScope.step_02);
          }
      };


      // All steps completed
      $scope.clickBtnStep03 = function(form) {
          //valid form
          if (form === true) {
              console.log('Form is valid, $rootScope.step_03 "'+ $rootScope.step_03);
              $rootScope.step_03 = true;
              $rootScope.notValidStpe_03 = true;

          }

          //invalid form
          if (form === false) {
              $rootScope.step_03 = false;
              $rootScope.notValidStpe_03 = false;
              console.log('Form is invalid, $rootScope.step_03= ' + $rootScope.step_03);
          }
      };

  });

}(window, window.angular));enter code here

e.g app.js code

(function() {

    'use strict';


    var myApp = angular
        .module('myApp', [
            'ngResource',
            'ngAnimate',
            'ngMessages',
            'templates'
        ]);


    myApp.run(function($rootScope) {
        $rootScope.step_01 = false;
        $rootScope.step_02 = false;
        $rootScope.step_03 = false;

        $rootScope.notValidStpe_01 = false;
        $rootScope.notValidStpe_02 = false;
        $rootScope.notValidStpe_03 = false;
    });

}(window, window.angular));

Answer 1

The clue is using the ngForm directive and assign a form name attribute which references to the $rootScope.

<form name="$root.myForm" id="form_id">
    <input type="text" name="myField" required>
</form>

<button form="form_id" ng-disabled="$root.myForm.myfield.$invalid">
    Submit
</button>

That works.