Asp.net core MVC post parameter always null

Question

I am new to MVC core.

I have created a project with MVC core which has a controller. This controller has Get and Post action methods. If i pass data to Get method using query string it works fine, but when i pass complex JSON to post method, then it always shows me null.

Here what i am doing:

Post Request

URL: http://localhost:1001/api/users
Content-Type: application/json
Body: 
{
   "Name":"UserName",
   "Gender":"Gender of the user",
   "PhoneNumber":"PhoneNumber of the user"
}

Here is the Post action method

[HttpPost]
[Route("api/users")]
public async Task<IActionResult> Post([FromBody]User newUser)
{
   ...
}

When post request is called, then newUser always shows me null. And if i remove [FromBody] attribute then i receive newUser object but all of its fields are null.

Please help me and guide me in this issue.

EDITED

Here is my User class

public class User{

   public int Id { get; set; }
   public string Name { get; set; }
   public string Gender { get; set; }
   public string PhoneNumber { get; set; }
}

I had done same as described here for json data, but still receives null.

DO you have any middleware that might intercept the request? have you done a wireshark or fiddler trace? — Toxicable, Jul 19 '16 at 10:33
No, I am sending request using postman. I don't know how to trace the request using fiddler. — Ravi Patel, Jul 19 '16 at 10:34
Download fiddler, and watch the requests and inspect them, make sure what you're sending matches up on the actual request. It's really not complicated to use — Toxicable, Jul 19 '16 at 10:36
Thanks i will try it, but meanwhile let me know if i am doing anything wrong in above code. — Ravi Patel, Jul 19 '16 at 10:39
Remove `[FromBody]` this extracts simple types from body. That explains why it works when you removed it. Check to make sure that the properties of your JSON match the `User` object so the that ModelBinder will populate the matching properties on the model. Show your definition of the `User` class — Nkosi, Jul 19 '16 at 11:59
@Nkosi I tried that too, and i am sure all the properties of JSON matches with the User object. Even though i get all properties as null — Ravi Patel, Jul 19 '16 at 12:04
While it may just be a typo, shouldn't your Content Type be `application/json` instead of `applicaton/json`? — Rion Williams, Jul 19 '16 at 12:58
Seems odd to post `"Id": null` when Id is an int (not nullable). — blins, Jul 19 '16 at 13:03
@blins I tried it sending **Id: 0** and also tried json with no **Id** property as well. Still it did not work. — Ravi Patel, Jul 19 '16 at 13:05

score 13 · Accepted Answer · answered Jul 21 '16 at 02:22

13

This could be because of how the null values are being handled. Set NullValueHandling to Ignore in AddJsonOptions and see if that works.

public void ConfigureServices(IServiceCollection services)
{
    services
        .AddMvc()
        .AddJsonOptions(jsonOptions=>
        {
            jsonOptions.SerializerSettings.NullValueHandling = Newtonsoft.Json.NullValueHandling.Ignore;
        });
}

answered Jul 21 '16 at 02:22

bvoleti

2,472
1
18
20

Thanks buddy, It worked just fine. Now i know why the data received was null. – Ravi Patel Jul 28 '16 at 07:13
1

THANK you .. I don't think I would have figured this out soon without your help. – m4design Dec 07 '16 at 16:47

score 11 · Answer 2 · answered Jan 05 '17 at 20:19

Note the original method Post([FromBody] User newUser)

For future readers from google, this same issue could arise if the method was Post(User newUser)

Note the lack of [FromBody]. This is a departure from previous versions of MVC where these parameters were generally inferred.

If you're an existing MVC5 developer who finds this page regarding AspNetCore.MVC, make sure to double check that you have [FromBody] decorated where relevant.

score 2 · Answer 3 · edited Jul 20 '16 at 01:50

2

I created new ASP.NET Core project, added your functionality, and it works. Please, checkout this project on github.

Also, see screenshot of log with simple communication with this controller from browser console: Console output

edited Jul 20 '16 at 01:50

R. Richards

24,603
10
64
64

answered Jul 19 '16 at 18:18

Roman Zinnatov

68
6

score 0 · Answer 4 · edited Jul 20 '16 at 00:25

0

Are you on Microsoft.AspNetCore.Mvc 1.0.0?

If you are, try sending this object as your body in a request (camel cased properties):

{
   "name":"UserName",
   "gender":"Gender of the user",
   "phoneNumber":"PhoneNumber of the user"
}

edited Jul 20 '16 at 00:25

svick

236,525
50
385
514

answered Jul 19 '16 at 14:04

steamrolla

2,373
1
29
39

Yes i am using Microsoft.AspNetCore.Mvc 1.0.0 Also i am sending data in the request body – Ravi Patel Jul 19 '16 at 14:07
Yes, but, use camel cased property names in the JSON. – steamrolla Jul 19 '16 at 14:09
It is the default in `Microsoft.AspNetCore.Mvc 1.0.0`. – steamrolla Jul 19 '16 at 14:36

Asp.net core MVC post parameter always null

4 Answers4

Linked