Web Api HTTPPost not accepting int

Question

I am trying to just pass in body a int and it does not work Why do I need to create a class with a property of type int ? (then it works)

WORKS

[HttpPost]
[Route("api/UpdateMainReversed")]
public IHttpActionResult UpdateMainVerified(DataAccess.Entities.RequestMain mainValues)
    {  ....}

DO NOT WORK

[HttpPost]
[Route("api/UpdateMainReversed")]
public IHttpActionResult UpdateMainVerified(int mainId)
    {  ....}

Testing with Postman

http://localhost:13497/api/UpdateMainReversed

Body

{
   "mainId" : 1615
}

body, because its POST and not supposed to pass in URL for proper REST — , Mar 16 '17 at 19:13

score 35 · Accepted Answer · answered Mar 16 '17 at 21:34

35

1.Your [HttpPost] expects a int but from body you are passing a json object. you should pass json string like below. No need to mention parameter name

2.you should use [FromBody] as below

[HttpPost]
    public void UpdateMainVerified([FromBody] int mainid)
    {

    }

this link explains it well

https://learn.microsoft.com/en-us/aspnet/web-api/overview/formats-and-model-binding/parameter-binding-in-aspnet-web-api

answered Mar 16 '17 at 21:34

Boopathy T

537
3
8

NICE JOB. I read several articles and was ready to give up as I could pass in a string instead of int to string mainid ... but value was null. THIS solution actually works! thx – Mar 16 '17 at 22:42
Also if using axios, post data as axios.post('/UpdateMainVerified', mainId) not as json i.e. axios.post('/UpdateMainVerified', {mainId: mainId}) – Michael Sep 10 '21 at 22:05

score 3 · Answer 2 · edited Feb 22 '19 at 15:20

3

Set FromBody Attribute.

To force Web API to read a simple type from the request body, add the [FromBody] attribute to the parameter.

For details Link

[HttpPost]
[Route("api/UpdateMainReversed")]
public IHttpActionResult UpdateMainVerified([FromBody] int mainId)
    {  ....}

edited Feb 22 '19 at 15:20

Martijn Pieters

1,048,767
296
4,058
3,343

answered Mar 16 '17 at 19:14

Muhammad Saqlain

2,112
4
33
48

{ "message": "The request is invalid.", "messageDetail": "The parameters dictionary contains a null entry for parameter 'mainId' of non-nullable type 'System.Int32' for method 'System.Web.Http.IHttpActionResult AddProduct(Int32)' i – Mar 16 '17 at 19:52
1

set Content-Type: application/x-www-form-urlencoded – Muhammad Saqlain Mar 16 '17 at 20:11
then it would no longer be JSON Muhammad ... I'm in your situation user6321478 , if anyone has a fix – Max Dec 10 '18 at 16:06

Web Api HTTPPost not accepting int

2 Answers2

Linked