类型'String'是一个意外的参数，期望Mysqli [mysqli_real_escape_string] [重复]

I'm trying to persist an angularjs element in my database.

I'm using mySQL and PHP.

When I try to persist, I obtain this error: Warning: 'dabdsa' of type 'String' is an unexpected argument, expected Mysqli [mysqli_real_escape_string]
Warning: function 'mysqli_real_escape_string' has 2 required arguments, but only 1 were provided [mysqli_real_escape_string]

I dont know what is happening.

My app.js code is:

var app = angular.module("TestIdoneidadApp", []);
                app.controller("TIController", ['$scope','$http', function($scope, $http) {
                    $scope.gestor= '';
                    $scope.entidad= ''; 
                    $scope.save=function(){

                        $scope.xml_object = '<?xml version="1.0" encoding="UTF-8" standalone="yes"?><testIdoneidad>';
                        $scope.xml_object += '<gestor>' + $scope.ti.gestor + '</gestor>';
                        $scope.xml_object += '<entidad>' + $scope.ti.entidad + '</entidad>';
                        $scope.xml_object += '</testIdoneidad>';
                        $http.post("insert.php", {'xml_object':$scope.xml_object});
                        }
                }]);

My insert.php code is:

<?php header('Access-Control-Allow-Origin: *');
header('Access-Control-Allow-Headers: Authorization, Content-Type');
header('Access-Control-Allow-Methods: GET, POST, OPTIONS, DELETE');
$servername = "localhost";
$username = "msandbox";
$password = "msandbox";
$dbname = "angular_db";
$port = "5631";
// Create connection
$conn = mysqli_connect($servername, $username, $password, $dbname, $port);
// Check connection
if (!$conn) {
    die("Connection failed: " . mysqli_connect_error());
}
$data = json_decode(file_get_contents("php://input"));
$xml_object = mysqli_real_escape_string($data->xml_object);
$sql = "INSERT INTO test_idoneidad (xml_object)
VALUES ('".$xml_object."')";

if (mysqli_query($conn, $sql)) {
    echo "New record created successfully";
} else {
    echo "Error: " . $sql . "<br>" . mysqli_error($conn);
}
mysqli_close($conn);
?>

The connection with database is correct, and if i try to insert something like "test" in the Value, this works.

Can someone help me?

Thank you in advice.

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