On a REST api i receive a Json that gets mapped to a Java Object:
#RequestMapping(value = "/example", method = RequestMethod.POST)
public #ResponseBody
ReturnObject doReturn(#RequestBody ProblemObject requestBody)
The object is simple:
public class ProblemObject implements Serializable {
private String field1;
private String field2;
public ProblemObject(String field2) {
this.field2 = field2;
}
public ProblemObject(String field1, String field2) {
this.field1 = field1;
this.field2 = field2;
}
}
The problem is Jackson tries to deserialize even malformed JSON, with not so good results, for example it accepts:
"field1": "test",
"field2": "test"
}
notice no opening brace. This causes the object to get mapped with field1 having a value of "field2" and field2 being null.
It also accepts no comma with even worse results.
For now the only alternative i can think of is implementing a custom deserialiser but that is not optimal imho.
Is there a way to make Jackson more strict?
I would try being more explicit in your #RequestMapping annotation and telling the API what it should be consuming:
#RequestMapping(value = "/example", method = RequestMethod.POST, consumes = MediaType.APPLICATION_JSON_VALUE)
This is apparently a bug in the TokenBuffer in Jackson. An issue has been opened and a Jackson dev has confirmed the bug.
It is due to the single String constructor. Removing the constructor if possible is a temporary workaround.
Related
I am trying to send parameters from UI to Spring MVC controller. My parameter looks like
caseId=23951910&serviceProvided%5B0%5D.id=25989&serviceProvided%5B0%5D.desc=24-Hour+Service&serviceProvided%5B0%5D.duration=1&serviceProvided%5B0%5D.pages=--&serviceProvided%5B1%5D.id=25988&serviceProvided%5B1%5D.desc=3rd+Party+Contact&serviceProvided%5B1%5D.duration=2&serviceProvided%5B1%5D.pages=--&serviceProvided%5B2%5D.id=25980&serviceProvided%5B2%5D.desc=Advice&serviceProvided%5B2%5D.duration=3&serviceProvided%5B2%5D.pages=--&serviceProvided%5B3%5D.id=25982&serviceProvided%5B3%5D.desc=Document+Preparation&serviceProvided%5B3%5D.duration=4&serviceProvided%5B3%5D.pages=--&serviceProvided%5B4%5D.id=DOCREVIEW&serviceProvided%5B4%5D.desc=Document+Review&serviceProvided%5B4%5D.duration=5&serviceProvided%5B4%5D.pages=6
To match this parameter I am using custom class as
Class MyDto {
private Long caseId;
private List<ServiceProvided> serviceProvided;
//getter and setter
}
Class ServiceProvided {
private String id;
private String desc;
private Long duration;
private Long pages;
//getter and setter
}
I have controller as
#RequestMapping(value = "/cases/resolveClaim.htm", method = RequestMethod.POST)
public ModelAndView createClaim(#ModelAttribute("claimInfo") MyDto myDto, BindingResult result) { ... }
I am getting 404 error so I am guessing "serviceProvided" list couldn't match to myDto. So my questions are:
Is this a really a reason I am getting 404 error?
If yes I guess I have to solve with PropertyEditor or Converter? Am I correct?
Is there any example code that I can refer to?
Thanks
I have a method in my controller that should returns a String in JSON. It returns JSON for non primitive types:
#RequestMapping(value = "so", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
ResponseEntity<String> so() {
return new ResponseEntity<String>("This is a String", HttpStatus.OK);
}
The curl response is:
This is a String
The root of the problem is that Spring (via ResponseEntity, RestController, and/or ResponseBody) will use the contents of the string as the raw response value, rather than treating the string as JSON value to be encoded. This is true even when the controller method uses produces = MediaType.APPLICATION_JSON_VALUE, as in the question here.
It's essentially like the difference between the following:
// yields: This is a String
System.out.println("This is a String");
// yields: "This is a String"
System.out.println("\"This is a String\"");
The first output cannot be parsed as JSON, but the second output can.
Something like '"'+myString+'"' is probably not a good idea however, as that won't handle proper escaping of double-quotes within the string and will not produce valid JSON for any such string.
One way to handle this would be to embed your string inside an object or list, so that you're not passing a raw string to Spring. However, that changes the format of your output, and really there's no good reason not to be able to return a properly-encoded JSON string if that's what you want to do. If that's what you want, the best way to handle it is via a JSON formatter such as Json or Google Gson. Here's how it might look with Gson:
import com.google.gson.Gson;
#RestController
public class MyController
private static final Gson gson = new Gson();
#RequestMapping(value = "so", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
ResponseEntity<String> so() {
return ResponseEntity.ok(gson.toJson("This is a String"));
}
}
#RequestMapping(value = "so", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
public #ResponseBody String so() {
return "This is a String";
}
import org.springframework.boot.configurationprocessor.json.JSONException;
import org.springframework.boot.configurationprocessor.json.JSONObject;
public ResponseEntity<?> ApiCall(#PathVariable(name = "id") long id) throws JSONException {
JSONObject resp = new JSONObject();
resp.put("status", 0);
resp.put("id", id);
return new ResponseEntity<String>(resp.toString(), HttpStatus.CREATED);
}
An alternative solution is to use a wrapper for the String, for instances this:
public class StringResponse {
private String response;
public StringResponse(String response) {
this.response = response;
}
public String getResponse() {
return response;
}
}
Then return this in your controller's methods:
ResponseEntity<StringResponse>
In our web app, using Spring MVC 3.2 we display many paginated lists of different objects, and the links to other pages in the list are constructed like this:
/servlet/path?pageNum=4&resultsPerPage=10&sortOrder=ASC&sortBy=name
although there might be additional request parameters in the URL as well (e.g., search filters).
So we have controller methods like this:
#RequestMapping(method = RequestMethod.GET, value="/ajax/admin/list")
public String ajaxlistGroups(Model model,
#RequestParam(value="pageNumber",required=false,defaultValue="0") Long pageNumber,
#RequestParam(value="resultsPerPage",required=false,defaultValue="10") int resultsPerPage,
#RequestParam(value="sortOrder",required=false,defaultValue="DESC") String sortOrder,
#RequestParam(value="orderBy",required=false,defaultValue="modificationDate")String orderBy) {
// create a PaginationCriteria object to hold this information for passing to Service layer
// do Database search
// return a JSP view name
}
so we end up with this clumsy method signature, repeated several times in the app, and each method needs to create a PaginationCriteria object to hold the pagination information, and validate the input.
Is there a way to create our PaginationCriteria object automatically, if these request params are present? E.g., replace the above with:
#RequestMapping(method = RequestMethod.GET, value="/ajax/admin/list")
public String ajaxlistGroups(Model model, #SomeAnnotation? PaginationCriteria criteria,
) {
...
}
I.e., is there a way in Spring to take a defined subset of requestParams from a regular GET request, and convert them to an object automatically, so it's available for use in the Controller handler method? I've only used #ModelAttribute before, and that doesn't seem the right thing here.
Thanks!
Spring 3.2 should automatically map request parameters to a custom java bean.
#RequestMapping(method = RequestMethod.GET, value="/ajax/admin/list")
public String ajaxlistGroups(Model model, PaginationCriteriaBean criteriaBean,
) {
//if PaginationCriteriaBean should be populated as long as the field name is same as
//request parameter names.
}
I'm not sure how Spring magically achieve this(without #ModelAttribute), but the code above works for me.
There is another way to achieve the same goal, you can actually achieve more, that is spring AOP.
<bean id="aspectBean" class="au.net.test.aspect.MyAspect"></bean>
<aop:config>
<aop:aspect id="myAspect" ref="aspectBean">
<aop:pointcut id="myPointcut"
expression="execution(* au.net.test.web.*.*(..)) and args(request,bean,..)" />
<aop:before pointcut-ref="myPointcut" method="monitor" />
</aop:aspect>
</aop:config>
in application context, we declare Aspect bean as well as Pointcut along with advice, which in your case is before advice
the following is source code
public class PaginationCriteriaBean {
private String id;
private String name;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
//custom Aspect
public class MyAspect {
public void monitor( HttpServletRequest request,PaginationCriteriaBean bean){
//populate your pagination bean
bean.setId(request.getParameter("id"));
bean.setName("my new name");
}
}
#RequestMapping(value="/app")
public String appRoot(HttpServletRequest request,PaginationCriteriaBean bean){
System.out.println(bean.getId());
System.out.println(bean.getName());
return "app";
}
by doing so, the aspect will intercept spring controller and populate PaginationCriteriaBean based on request parameters, and you can even change the original value in request. With this AOP implementation you are empowered to apply more logic against Pagination, such as logging and validation and etc.
All,
I have an instance of ProjectBudget class returned from a web method.
Ex:
[WebMethod()]
public ProjectBudget LoadBudget(int id)
{
ProjectBudget budget = BudgetManager.LoadBudget(id);
return budget;
}
The ProjectBudget class contains the following defintion:
public class ProjectBudget
{
public int Id = -1;
public long VersionNumber = -1;
public string QuoteNumber = "";
public string CurrencyCode = "";
public ProjectInfo Project;
public ClientInfo Client;
public readonly List<InventoryItem> Inventory = new List<InventoryItem>();
public readonly List<Staff> Staff = new List<Staff>();
public readonly List<CodeType> Departments = new List<CodeType>();
public readonly SerializableDictionary<string, string> Tasks = new SerializableDictionary<string, string>();
public ProjectBudget()
{
}
}
All public fields you see are serialized just fine with the exception of Tasks field, which is completely ignored by XML serializer. Since we all know by now that Dictionaries cannot be handled by XML serializer, I use a serializable dictionary (which is just a dictionary that implements IXmlSerializable) here but XML serializer decides to ignore it completely, i.e. the XML output does not contain any tasks and the generated proxy class doesn't have this field.
I need to figure out how to tell the XML serializer not to omit this field.
Btw, what is interesting is that a web method that returns SerializableDictionary works fine!
A very similar question as yours appears to have been asked already: Link.
Use DataContractSerializer or try explicitly implementing your getter (and setter), as per this link.
I am having trouble deserializing my JSON string. I have a class of type person with public properties for sequence number of type int, first name, and last name. I want to pass an array of these objects in JSON format and have them deserialized as a list so I can loop through them on the server, but ASP.NET says something about not being supported to be deserialized as an array. I have validated the JSON I am producing, and it is valid. Is there something special about the JSON that ASP.NET needs to have before it can deserialize? The funny thing is if I serialize a list<person> object to JSON it looks exactly like the JSON I am producing. I must be missing something... To clarify, I'm using the ASP.NET Ajax library to deserialize. This is what I get back from the web service:
{"Message":"Type \u0027System.Collections.Generic.IDictionary`2[[System.String, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089],[System.Object, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]]\u0027 is not supported for deserialization of an array."
Actually unfortunately this doesn't seem to have anything to do with deserializing, it appears that you can't pass an array of JSON objects to an asmx web service. Am I correct? If you can't do that, is it possible to pass a collection of JSON objects to a web service and have them processed on the server with ASP.NET and C#?
Update:
OK, here is my code. Here is the person class:
public class person
{
public person()
{
//
// TODO: Add constructor logic here
//
}
public int seq
{
get;
set;
}
public string firstName
{
get;
set;
}
public string lastName
{
get;
set;
}
}
And here is my JSON string:
[{"seq":1,"firstName":"Chris","lastName":"Westbrook"},
{"seq":2,"firstName":"sayyl","lastName":"westbrook"}]
And here is the code I'm using
[WebMethod]
public void updatePeople(string json)
{
IList<person> people =
new JavaScriptSerializer().Deserialize<IList<person>>(json);
//do stuff...
}
I figured it out. I wasn't wrapping my JSON in an object like ASP.NET Ajax requires. For future viewers of this question, all JSON objects must be wrapped with a main object before being sent to the web service. The easiest way to do this is to create the object in JavaScript and use something like json2.js to stringify it. Also, if using an asmx web service, the objects must have a __type attribute to be serialized properly. An example of this might be:
var person=new object;
person.firstName="chris";
person.lastName="Westbrook";
person.seq=-1;
var data=new object;
data.p=person;
JSON.stringify(data);
This will create an object called p that will wrap a person object. This can then be linked to a parameter p in the web service. Lists of type person are made similarly, accept using an array of persons instead of just a single object. I hope this helps someone.
Could you show the JSON string you are trying to deserialize and the way you are using the Deserialize method? The following works fine:
using System;
using System.Collections.Generic;
using System.Web.Script.Serialization;
namespace Test
{
class Program
{
class Person
{
public int SequenceNumber { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
}
public static void Main()
{
string json = "[{\"SequenceNumber\":1,\"FirstName\":\"FN1\",\"LastName\":\"LN1\"},{\"SequenceNumber\":2,\"FirstName\":\"FN2\",\"LastName\":\"LN2\"}]";
IList<Person> persons = new JavaScriptSerializer()
.Deserialize<IList<Person>>(json);
Console.WriteLine(persons.Count);
}
}
}
Or even simpler, when you are doing the $.ajax(...) use
data:"{\"key\":"+JSON.stringify(json_array)+"}",
and then on the other side of the code, make your function use the parameter "object key"
[WebMethod]
public static return_type myfunction(object key){...}
SERVER SIDE
[WebMethod]
public void updatePeople(object json)
CLIENT SIDE
var person = "[{"seq":1,"firstName":"Chris","lastName":"Westbrook"}
,{"seq":2,"firstName":"sayyl","lastName":"westbrook"}]";
var str = "{'json':'" + JSON.stringify(person) + "'}";
I think the problem is what type you have to deserialize. You are trying to deserialize type
IList
but you should try to deserialize just
List
Since interface can not be instantiated this might is the root problem.