Field $valid state is not updating after $setValidity(True) - validation

Question

I'm using ui-validate for my validation rules.
<input ng-model=raw.expression
name="expression"
type="text"
required
ui-validate="{serversidevalid : 'validate_serverside($value)'}">
The validation is executed server side, the short version ... in the controller
$scope.validate_serverside = function(expression) {
someValidationFactory
.validate(expression)
.then(function(server_error_message) {
var validity = true,
error_message = false,
input = $scope.my_form['expression'];
if (server_error_message !== undefined) {
validity = false;
error_message = server_error_message;
}
input.$setValidity('serversidevalid',validity);
input.$error.serversidevalid = error_message;
});
Now, after this function is executed with a valid expression - The form's status is valid, The $error key and message are as exepected but the field's $valid / $invalid remains invalid.
How is it possible for the entire form to become valid but the field to remain invalid ?
I tried wrapping the two last statements with $scope.$apply or explicitly trigger $scope.$digest() but the it throws an "digest already in progress". I tried wrapping the thing with $timeout to execute after the digest is done - same undesired result.
appreciate some guidance here.

Answer 1

So I came across this discussion on github and after a quick look at the code I relaized that as of the last couple of month ui-validate support server side validation via promises.
So I dropped the external manipulation of $setValidity and changed my validation as follows
$scope.validate_serverside = function(expression) {
var deferred = $q.defer();
someValidationFactory
.validate(expression)
.then(function(server_error_message) {
if (server_error_message !== undefined)
deferred.reject(false)
else
deferred.resolve(true)
});
return deferred.promise;
}