Angular and spring REST API : NULL POINTER EXCEPTION - angularjs

Question

I GET NullPointerException with status code : 400
I am pushing data into a JsonObject and then post it to my back end (Spring ) and get the field using Json mapper (data.get("Field name").asText;.
I also tried get(index) and data.path but this return null, where as in the debug console It indicates that Json objects were received, what is it that makes these fields to be null?
Is it because this data is not directly from ng-model, or is it because I have pushed it into json object using Angular, because I am getting 400 erro code.
MY ANGULAR JS :
app.controller("OrderOperationsCtrl", function($scope, $http,$window) {
$http.get(productURL).then(function(response) {
$scope.productData = response.data;
$scope.newData = [];
$scope.total = 0.0;
$scope.sync = function(bool,productData,submit){
if(bool === true){
var numberOrdered = 0;
numberOrdered++;
$scope.total = $scope.total + productData.price;
var newD = $scope.newData.push({
"numberOrdered":numberOrdered,
"customerId":localStorage.getItem('takealot_customer'),
"id":productData.id,
"total":$scope.total
});
$scope.sender = $scope.newData;
console.log(" NewD " + $scope.newData);
}
if(submit === true){
$http.put(orderURL,JSON.stringify($scope.sender)).then(function(response){
if(response.data)
console.log("Order created !");
},function(response){
console.log("Error creating Order !");
console.log(response.status);
});
MY SPRING CONTROLLER UPDATE
public ResponseEntity createOrder(#RequestBody OrderOperations[] operation) throws OrderOperationsNotFoundException, IOException{
logger.info("recieved json String " + operation);
services.createOrder(operation);
return new ResponseEntity(HttpStatus.OK);
}
CONSOLE OUTPUT :
Hibernate: select products0_.id as id1_3_, products0_.category as category2_3_, products0_.description as descript3_3_, products0_.name as name4_3_, products0_.price as price5_3_, products0_.quantity as quantity6_3_, products0_.supplier as supplier7_3_ from products products0_
2017-11-03 11:34:41.689 INFO 10504 --- [nio-8080-exec-9]
c.p.C.OrderOperationsController : recieved json String
[{"numberOrdered":1,"customerId":null,"id":1,"total":78.32,"$$hashKey":"object:17"},
{"numberOrdered":1,"customerId":null,"id":2,"total":156.70999999999998,"$$hashKey":"object:19"},
{"numberOrdered":1,"customerId":null,"id":1,"total":235.02999999999997,"$$hashKey":"object:21"}]
THanks in advance

Answer 1

First of all you dont need to map the json into the OrderOperation Object.
Spring will automatically convert the JSON Object into OrderOperations by passing as Parameter
public ResponseEntity createOrder(#RequestBody OrderOperations operation)
And i think you get the Nullpointer while you parsing the Data

Answer 2

Finally I have got a solution. some weeks ago.
- For those who are still struggling to save multiple objects from JSON array
see below ... I hope this helps someone else.
public List<String> createOrder(#RequestBody OrderOperations[] json) throws OrderOperationsNotFoundException, IOException{
logger.info("recieved json String " + json);
List<String> response = new ArrayList<String>();
for(OrderOperations op : json){
services.createOrder(op);
response.add("saved order : " + op.toString());
}
return response;
}