I'm trying to fetch my asp .net core api in react-native app. When i am testing wiht postman this api is working fine. But in react-native i have this eror.

["https://tools.ietf.org/html/rfc7231#section-6.5.13", "Unsupported Media Type", 415, "00-2608a636e0aeaf4bb2b29a2e1b54370a-2145e9063626d940-00"]

This is my api. I have tried public JsonResult but nothing change.

 [HttpPost("register")]
        public IActionResult Register([FromBody] TbPersonel model)
        {
            try
            {
                // SOME CASES

                if (dt.Rows.Count > 0)
                {
                    model.login = true;                   
                    return new JsonResult(model.login);
                }
                else
                {
                    model.login = false;                   
                    return new JsonResult(model.login);
                }
            }
            catch (Exception e)
            {
                Logla.Log(MethodBase.GetCurrentMethod().Name, ControllerContext.ActionDescriptor.ControllerName, e);
                return new JsonResult(e);
            }
        }

React-Native

 fetch('http:/.../api/login/register/',{
            method:'post',
            header:{
                'Accept': 'application/json',
                // 'Content-type': 'application/json'
        'Content-Type': 'application/json; charset=utf-8'
            },
            body:JSON.stringify({               
                'kullaniciAdi': userName,
                'sifre': userPassword
            })          
        })    
        .then((response) => response.json())
         .then((responseJson)=>{
       console.log(Object.values(responseJson));

Postman Post request

Postman headers

CodePudding user response：

The problem is in the parameters of fetch. fetch doesn't have any parameter named header but it's headers with an s. So, your code wasn't asking for the correct Content-type and Accept Headers. To fix this just add an s to the header key :

fetch('http:/.../api/login/register/',{
        method:'post',
        headers:{
            'Accept': 'application/json',
            // 'Content-type': 'application/json'
    'Content-Type': 'application/json; charset=utf-8'
        },
        body:JSON.stringify({               
            'kullaniciAdi': userName,
            'sifre': userPassword
        })          
    })    
    .then((response) => response.json())
     .then((responseJson)=>{
   console.log(Object.values(responseJson));

Unfortunately, Javascript doesn't highlight this error.