How to achieve that "ui-sref" be conditionally executed?

I want to validate certain condition before the browser follow the link dynamically created by ui-router.

I was looking into $rootscope.$on('$stateChangeStart', ..) but I have no access to the controller.$scope from there. I also need to use this in several places in the application and would be cumbersome.

Keep in mind that ui-sref is linked to ui-sref-active (work together), so i can't remove ui-sref and, by say, to use $state.$go('some-state') inside a function called with ng-click.

The condition should be evaluated inside a $scope function and on on-click event (before-transition with the ability to cancel it)

I need something like this:

<li ui-sref-active="active">
      <a ui-sref="somestate" ui-sref-if="model.validate()">Go Somestate</a>
</li>

I tried:

<li ui-sref-active="active">
      <a ui-sref="somestate" ng-click="$event.preventDefault()">Go Somestate</a>
</li>

<li ui-sref-active="active">
      <a ui-sref="somestate" ng-click="$event.stopImmediatePropagation()">Go Somestate</a>
</li>

And

<li ui-sref-active="active">
    <a ui-sref="somestate">
       <span ng-click="$event.stopPropagation();">Go Somestate</span>
    </a>
</li>

Even

<li ui-sref-active="active">
      <a ui-sref="somestate" onclick="return false;">Go Somestate</a>
</li>

But does not work.

SANDBOX

This answer inspired me to create a directive that allows me to interrupt the chain of events that end up changing state. For convenience and other uses also prevents the execution of ng-click on the same element.

javascript

module.directive('eatClickIf', ['$parse', '$rootScope',
  function($parse, $rootScope) {
    return {
      // this ensure eatClickIf be compiled before ngClick
      priority: 100,
      restrict: 'A',
      compile: function($element, attr) {
        var fn = $parse(attr.eatClickIf);
        return {
          pre: function link(scope, element) {
            var eventName = 'click';
            element.on(eventName, function(event) {
              var callback = function() {
                if (fn(scope, {$event: event})) {
                  // prevents ng-click to be executed
                  event.stopImmediatePropagation();
                  // prevents href 
                  event.preventDefault();
                  return false;
                }
              };
              if ($rootScope.$$phase) {
                scope.$evalAsync(callback);
              } else {
                scope.$apply(callback);
              }
            });
          },
          post: function() {}
        }
      }
    }
  }
]);

html

<li ui-sref-active="active">
      <a ui-sref="somestate" eat-click-if="!model.isValid()">Go Somestate</a>
</li>

PLUNKER

You can use a scope function that will either returns :

no state
an existing state

like so :

HTML :

<li ui-sref-active="active">
      <a ui-sref="{{checkCondition()}}">Go Somestate</a>
</li>

JS scope :

$scope.checkCondition = function() {
    return model.validate()
        ? 'someState'
        : '-' // hack: must return a non-empty string to prevent JS console error
}

href attribute will be created only when the function returns an existing state string.

Alternatively, you could do a (ugly) :

<li ui-sref-active="active">
      <a ui-sref="somestate" ng-if="model.validate()">Go Somestate</a>
      <span ng-if="!model.validate()">Go Somestate</span>
</li>

Hope this helps

The easiest workaround to conditionally achieve routing without tinkering with directives, scope etc was a workaround i found here - https://github.com/angular-ui/ui-router/issues/1489

<a ui-sref="{{condition ? '.childState' : '.'}}"> Conditional Link </a>

How to achieve that "ui-sref" be conditionally executed?

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