如何在Blazor中同步调用HttpClient

Question

我想在Blazor中同步调用API，但它不起作用。有没有办法同步调用API。请查找以下代码。

当前使用异步调用，如下所述：

if(HttpClient == null)
{
HttpClient = new HttpClient();
HttpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", userContext.Token);
}
var json = JsonConvert.SerializeObject(request);
HttpContent content = new StringContent(json, Encoding.UTF8, "application/json");

var httpResponse = await HttpClient.PostAsync(api, content);

httpResponse.EnsureSuccessStatusCode();

var response = await httpResponse.Content.ReadAsStringAsync();
var parsedResult = JObject.Parse(response);
return parsedResult["returnObj"].ToString();

尝试了以下方式，但Blazor不支持：

string response;
WebRequest webRequest = WebRequest.Create($"{userContext.ServerAddress}/Erp.BO.ConfigurationRuntimeSvc/{apiName}");
webRequest.Method = "POST";
webRequest.Headers.Add("Authorization", "Basic " + userContext.Token);
webRequest.ContentType = "application/json";

// Create POST data and convert it to a byte array.
var json = JsonConvert.SerializeObject(request);

using (var streamWriter = new StreamWriter(webRequest.GetRequestStream()))
{
streamWriter.Write(json);
streamWriter.Flush();
}

var httpResponse = (HttpWebResponse)webRequest.GetResponse();
using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))
{
response = streamReader.ReadToEnd();
}

var parsedResult = JObject.Parse(response);
return parsedResult["returnObj"].ToString();

请提供解决方案

Answer 1

不知道这是否对你有帮助，但不久前在Github:上也提出了类似的问题

https://github.com/dotnet/aspnetcore/issues/16217

编辑：

文章摘要：

基本上，您不应该进行同步Http调用。首选选项：var result = await HttpClient.GetJsonAsync<T>(myUrl);

如果你真的想同步，这就是解决方案：

如果需要，可以在启动渲染器之前运行异步操作。例如，

static void Main(string[] args)
{
Task.Run(async () =>
{
var serviceProvider = new BrowserServiceProvider(services =>
{
// Add any custom services here
});
// First run an async HTTP request
var httpClient = serviceProvider.GetService<HttpClient>();
var data = await httpClient.GetStringAsync("/api/SampleData/WeatherForecasts");
Console.WriteLine("Fetched data: " + data);
// Now the request is completed, start rendering the UI
new BrowserRenderer(serviceProvider).AddComponent<App>("app");
});
}

这是首选的解决方案，而不是试图阻止UI线程(浏览器不允许-他们会说选项卡崩溃了如果您正在阻塞UI线程(。