ajax post call causes 400 (Bad Request) on sending array to spring rest controller

Question

I have OneToMany mapping as

@Entity
public class Foo implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long fooId;
    private String fooName;     

    @OneToMany(mappedBy = "foo", cascade = CascadeType.ALL)
    private Set<Bar> bars = new HashSet<Bar>();

    // getters and setters go here
}

and

@Entity
public class Bar implements Serializable {     
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long barId;
    private String barTitle;
    private static final long serialVersionUID = 1L;
    @ManyToOne
    @JoinColumn(name = "fooId")
    private Foo foo;
    // getters and setters go here
}

I've created a FooRestController to save data using ajax

@RequestMapping(value = "/foo/", headers="Accept=*/*", consumes="application/json", method = RequestMethod.POST)
    public ResponseEntity<Void> create(@RequestBody Foo foo) {           
        fooService.saveFoo(foo);
        Set<Bar> bars = foo.getBars();      

        for (Bar bar : bars) {
            barService.savebar(bar);            
        }       

        return new ResponseEntity<Void>(HttpStatus.CREATED);
    }

my ajax POST request is

var barArray = [];
bar[0] = "Bar1";
bar[1] = "Bar2";
$.ajax({
    contentType : 'application/json',
    crossDomain: true,
    type: 'POST',
    url: '/foo/',
    dataType : 'json',
    data : JSON.stringify({        
        'fooName' : 'A',
        'bars' : barArray // this line here causes error 
})

at this point I'm getting error as

POST http://localhost:8080/name/foo/ 400 (Bad Request)

any suggestions for saving barArray of foo.

Note

when ever I send data using Postman as

{

    "fooName": "A",       
   "bars" : [
         {
            "barTitle" : "a"                
         }           
       ]
}

data is inserted and a new foo is created in db.

Answer 1

As for as my approach is concerned the problem is clear that you should send barArray as you are sending it in Postman so write this code

var barArray = [];
bar[0] = "Bar1";
bar[1] = "Bar2";
$.ajax({
    contentType : 'application/json',
    crossDomain: true,
    type: 'POST',
    url: '/foo/',
    dataType : 'json',
    data : JSON.stringify({        
        'fooName' : 'A',
        'bars' : [{
                 "barTitle" : bar[0], 
               },{
                 "barTitle" : bar[1], 
               }]
})

and make a bit change in rest controller for saving fooId in Bar entity in this way

@RequestMapping(value = "/foo/", headers="Accept=*/*", consumes="application/json", method = RequestMethod.POST)
    public ResponseEntity<Void> create(@RequestBody Foo foo) {           
        fooService.saveFoo(foo);
        Set<Bar> bars = foo.getBars();      

        for (Bar bar : bars) {
            bar.setFoo(foo); // this foo object comes from method arg @RequestBody Foo foo above
            barService.savebar(bar);            
        }       

        return new ResponseEntity<Void>(HttpStatus.CREATED);
    }

try it out and hope now you don't see 400 error.