Custom validation depending on another input - angularjs

Question

The idea is very simple. I have two inputs, and I validate them only if both are touched. At least one has to be different than 0. Where am I going wrong?
The HTML
<div class="form-group" ng-class="{'has-error' : (myForm.$submitted || myForm.for.$touched) && myForm.for.$invalid }">
<label class="col-md-4 control-label" for="for">For</label>
<div class="col-md-8">
<input class="form-control" id="for" name="for" ng-model="item.for" ng-required="(some expression)" type="number" one-not-zero="item.against" one-not-zero-touched="myForm.against.$touched"/>
<div ng-messages="myForm.for.$error" role="alert" ng-show="(myForm.$submitted || myForm.for.$touched) && myForm.for.$invalid">
<div class="help-block" ng-message="required">
REQUIRED
</div>
<div class="help-block" ng-message="oneNotZero">At least one has to be different than 0</div>
</div>
</div>
</div>
<div class="form-group" class="{'has-error' : (myForm.$submitted || myForm.against.$touched) && myForm.against.$invalid }">
<label class="col-md-4 control-label" for="against">Against</label>
<div class="col-md-8">
<input class="form-control" id="against" name="against" ng-model="item.against" ng-required="(some expression) " type="number" one-not-zero="item.for" one-not-zero-touched="myForm.for.$touched"/>
<div ng-messages="myForm.against.$error" role="alert" ng-show="(myForm.$submitted || myForm.against.$touched) && myForm.against.$invalid">
<div class="help-block" ng-message="required">
REQUIRED
</div>
<div class="help-block" ng-message="oneNotZero">At least one has to be different than 0</div>
</div>
</div>
</div>
The Directive
var oneNotZero = function() {
return {
restrict: "A",
require: "ngModel",
scope: {
oneNotZero: "=",
oneNotZeroTouched: "="
},
link: function(scope, element, attrs, ctrl) {
ctrl.$validators.oneNotZero = function (modelValue, viewValue) {
return scope.oneNotZeroTouched ? !((viewValue == 0) && (scope.oneNotZero == 0)) : true;
};
}
};
};
myModule.directive("oneNotZero", oneNotZero);
EDIT: I made some progress, changed the code to my latest version, but it doesn't fully work. If I don't make any changes to the values, and just go trough the inputs until I get to the submit button and hit enter, the validation doesn't fire. SHould I $watch the changes on the inputs?

Answer 1

This will submit the form if at least one field is not 0 else will display an error message.
<form name="myForm" novalidate>
<input name="for" ng-model="item.for" type="number" required>
<input name="against" ng-model="item.against" type="number" required>
<input type="submit" value="Submit">
<div ng-show="myForm.$submitted && (item.for == 0 || item.against == 0)">
At leat one field must be different from 0.
</div>
</form>