Comparing input value with value of an array in AngularJS

Question

I have a problem with the validation about existing values. I don't know how to compare two values and add the new value only, when it isn't exist in the Database. I've tried with angular.forEach() but it adds the new object always when the compare (what I'm doing with angular.equals()) isn't false and thats wrong. The object have to be only one time in the database.

Here is my create function:

$scope.createItem = function (createItem) {
   //here I have to define a query to compare createItem.lname with the table list (array items from the db) in the view.

   //That was the code:
   angular.forEach(nameslist, function (value) {
     if (angular.equals(createItem.lname, value.lname)) {
           CrudService.create(createItem).then(
              function () {
                //success code
                $scope.createItem = null;
              },
              function (err) {
               //error code
              });
           }
     }
   });
} 

Can anyone give me some help.. I don't know how to solve it.

Answer 1

var itemAbsent = namelist.map(function(value){
   return value.name;
}).indexOf(createItem.name) < 0;

if (nameAbsent){
   CrudService.create(createItem).then(
          function () {
            //success code
            $scope.createItem = null;
          },
          function (err) {
           //error code
          });
       }
}