问题

I made a form in Blazor WebApplication (Client). When submited, all data gets posted to a Server, where it gets processed. The server then sends a response to the client whether the operation was successful or not, but the SendAsync() method does not return any response from the server.

string json = <Serialized Object>;

var request = new HttpRequestMessage(HttpMethod.Post, "https://<server_address>");
request.Content = new StringContent(json);
request.SetBrowserRequestMode(BrowserRequestMode.NoCors);

using (var client = new HttpClient())
{
var response = await client.SendAsync(request).ConfigureAwait(false);
bool isSuccessCode = response.IsSuccessStatusCode; // false

string responseStr = await response.Content.ReadAsStringAsync().ConfigureAwait(false);
Console.WriteLine(responseStr); // prints empty string
if (responseStr == "Success")
    return true;
else
    return false;

}

The response variable does not contain any useful data, but only has default values in it (0s and nulls).

When I tried the same code(methods) with the same config (except CORS) in a console app, it worked without any problems and I got the desired response from the server.

// This worked
internal static async Task<string> Post(string url)
{
var request = new HttpRequestMessage(HttpMethod.Post, url);
request.Content = new StringContent(data);

using var client = new HttpClient();
var result = await client.SendAsync(request).ConfigureAwait(false);
return await result.Content.ReadAsStringAsync().ConfigureAwait(false); // proper response was returned

}

Link to a GitHub project showing my issue: https://github.com/SjamesE/SendAsync-BugReport/

string json = <Serialized Object>;
var request = new HttpRequestMessage(HttpMethod.Post, "https://<server_address>");
request.Content = new StringContent(json);
request.SetBrowserRequestMode(BrowserRequestMode.NoCors);
using (var client = new HttpClient())
{
    var response = await client.SendAsync(request).ConfigureAwait(false);
    bool isSuccessCode = response.IsSuccessStatusCode; // false
    string responseStr = await response.Content.ReadAsStringAsync().ConfigureAwait(false);
    Console.WriteLine(responseStr); // prints empty string
    if (responseStr == "Success")
        return true;
    else
        return false;
}

// This worked
internal static async Task<string> Post(string url)
{
    var request = new HttpRequestMessage(HttpMethod.Post, url);
    request.Content = new StringContent(data);
    using var client = new HttpClient();
    var result = await client.SendAsync(request).ConfigureAwait(false);
    return await result.Content.ReadAsStringAsync().ConfigureAwait(false); // proper response was returned
}

答案1

得分: -2

对于无意中发现这篇帖子的任何人：您不能在Blazor WebAssembly应用程序上进行无跨域请求。当使用以下代码行时，您可以发送请求，但响应不会返回到您的代码。

request.SetBrowserRequestMode(BrowserRequestMode.NoCors);

如果您仍然需要使用这些请求的响应，您需要切换到Blazor Server应用程序，或者创建一个主机并通过它路由您的请求。

request.SetBrowserRequestMode(BrowserRequestMode.NoCors);