HttpClient httpClient = new HttpClient();
        MyRequest request = new MyRequest (data);

        var content = new StringContent(System.Text.Json.JsonSerializer.Serialize(request), System.Text.Encoding.UTF8, "application/json");

        HttpRequestMessage httpRequestMessage = new HttpRequestMessage
        {
            RequestUri = new Uri("http://localhost:8000/api/action"),
            Content = content,
            Method = HttpMethod.Post          
        };
      
        httpRequestMessage.SetBrowserRequestMode(BrowserRequestMode.NoCors);
            
        await httpClient.SendAsync(httpRequestMessage);

Using HttpClient in Blazor WebAssembly I am trying to send a request to an API.

However, despite specifying application/json as the content type it sends text/plain;charset=UTF-8 (as viewed in the Chrome Network tab). This results in the API throwing an error.

CodePudding user response：

I think you could check these case：

CodePudding user response：

Related post: Wrong Content-Type being substituted for fetch http request

HttpClient in WebAssembly calls the standard fetch method.

As per the fetch specification when using no-cors only a limited number of content-types can be used: https://fetch.spec.whatwg.org/#simple-header

• "application/x-www-form-urlencoded"
• "multipart/form-data"
• "text/plain"

The preferred solution would be to correctly configure the end point you are calling to allow cross origin requests and not to use no-cors e.g: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Access-Control-Allow-Origin Access-Control-Allow-Origin: *

If this is not possible (as in my case) and you must use no-cors the only other option would be to change your end point to map "text/plain" to "application/json"

Whilst many may not consider this a bug it is an inconsistency in how HttpClient behaves and is not obvious (though the NoCors option is only available in WebAssembly)