add selected value from dropdown list to database angularjs php mysql

i have a dropdown list and i can access the selected name through ng_model directive(selectedName) but My problem is when i try to pass the selected option value to the database it pass a null value the query get executed and text box values are passing properly the issue is with the dropdown option values.. what went wrong .. in the controller or with the php code mysqli_real_escape_string part. it's confused .. any help

<select data-ng-model="selectedName" ng-options="item for item in names">
</select>

var app = angular.module('myApp', []);
app.controller('myCtrl',  function($scope)  {
$scope.names = ["7G", "8G", "13G", "15G", "23G","26G"];


   app.controller("usercontroller", function($scope, $http){
    $scope.insertData = function(){
        $http.post(
            "insert.php",
            {'selectedName':$scope.selectedName, 
'selectedProject':$scope.selectedProject,  'user':$scope.user}
        ).success(function(data){
            alert(data);
        });
    }


$connect = mysqli_connect("localhost","root","","microlinks");  
$data = json_decode(file_get_contents("php://input"));
if(count($data) > 0){
$frequency = mysqli_real_escape_string($connect, $data->selectedName);
$project = mysqli_real_escape_string($connect, $data->selectedProject);
   $user = mysqli_real_escape_string($connect, $data->user);


$query = "insert into links(frequency,project,user,date) values ('$frequency','$project', '$user',)";

if(mysqli_query($connect, $query))
{
    echo "Hello World";
}
else
{
    echo 'Error';
}
}