How does one pass an argument to a directive without over-writing parent scope?

Question

I need to create a directive that acts upon table cells where the table rows are rendered using ng-repeat -- to that end I have relied in part on this answer to a question entitled "Calling a function when ng-repeat has finished". Unlike that Q&A however, I need to pass in an argument to my directive, and for this I have relied in part on this answer (to a question entitled "Angularjs - Pass argument to directive").

So in my case I've added fixed-column-tooltip for my directive, and columnselector as its argument to the <tr> as follows:

<tr fixed-column-tooltip columnselector=".td-keyField" ng-repeat="trData in trDataWatch">

But when per the second answer, I added what I've learned is an "isolate scope" to my directive, I no longer had access to the original scope necessary as per the first answer:

'use strict';

angular.module('cmt.cases.directives')

.directive('fixedColumnTooltip', function ($timeout) {
    return {
        restrict: 'A',
        scope: {
            columnselector: '@'
        },
        link: function (scope, element, attr) {
            if (scope.$last === true) { //undefined because not operating on original scope
        ...

Is there a way to maintain access to the original scope, but also have access to the columnselector argument?

Answer 1

You could use,

'use strict';

angular.module('cmt.cases.directives')

.directive('fixedColumnTooltip', function ($timeout) {
    return {
        restrict: 'A',
        scope: {
            columnselector: '@',
            $last: '=$last',
        },
        link: function (scope, element, attr) {
            if (scope.$last === true) {
            ....

the second parameter to scope will pass $last parameter by reference.

EDIT:

Since the $last is only available in the scope of repeat element, you could get it from the element scope, like this

'use strict';

angular.module('cmt.cases.directives')

.directive('fixedColumnTooltip', function ($timeout) {
return {
    srestrict: 'A',
    scope: {
        columnselector: '@',
    },
    link: function (scope, element, attrs) {
      var elemScope = element.scope();
      if (elemScope.$last){
             ......
      }          
    }
}