How to return a list of object as Json in Spring MVC

Question

I'm trying to get a list of objects to render on a Spring 3 MVC app and would like to do this via Ajax.

So in my Spring class I have:

@RequestMapping(value = "/viewSearchEnquiriesAjax", method = RequestMethod.GET, headers = "Accept=application/json")
public @ResponseBody List<Enquiry> getEnquiriesBySearchAjax(@RequestParam String name) {
    Search search =  new Search();
    search.setFirstName(name);
    return searchEnquiries(search);
}

But I get a 500 (Internal Server Error) when this is run. This manifests itself when I'm debugging in the browser as 'GET http://localhost:8080/SpringMVC/viewSearchEnquiriesAjax?name=peter 500 (Internal Server Error)'

I can successfully return a single object with no error. Can the Spring Json mapper(Jackson) convert correctly? Am I missing something fundamental?

My javascript is as follows:

function doAjaxPost() {
// get the form values
var firstName = $('#firstName').val();
$.getJSON("/SpringMVC/viewSearchEnquiriesAjax", { name: firstName }, function(result) {
    alert("Success");
 });

}

My Enquiry object is an Entity:

@Entity
@Table(name = "enquiries")
public class Enquiry implements java.io.Serializable{

    private static final long serialVersionUID = -5093725544297637792L;

    protected Long id;
    protected Date created = new Date();
    ...
    ...

    public Enquiry() {
    }

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "id", unique = true, nullable = false)
    public Long getId() {
        return this.id;
    }

    public void setId(Long id) {
        this.id = id;
    }
   ...
   ...

Answer 1

For Jackson you have to create a strongly typed list class because of type erasure:

public class EnquiryList extends ArrayList<Enquiry> {
}

Then return this list from your controller:

@RequestMapping(value = "/viewSearchEnquiriesAjax", method = RequestMethod.GET, headers = "Accept=application/json")
public @ResponseBody EnquiryList getEnquiriesBySearchAjax(@RequestParam String name) {
    EnquiryList list = new EnquiryList();
    ...
    return list;
}

Also check out this answer on a similar question.