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blazor - 对控制器的 HttpClient 请求返回“不支持提供的 ContentType ...”

问题描述

我创建了另一个与使用默认 Blazor WebAssembly 项目创建的默认 WeatherForestcastController 相同的控制器，并将控制器命名为“IncidentController”。默认 WeatherForestcastController 的唯一变化是名称：

[ApiController]
[Route("[controller]")]
public class **IncidentController** : ControllerBase
{
    private static readonly string[] Summaries = new[]
    {
        "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
    };

private readonly ILogger<**IncidentController**> logger;

public **IncidentController**(ILogger<**IncidentController**> logger)
{
    this.logger = logger;
}

[HttpGet]
public IEnumerable<WeatherForecast> Get()
{
    var rng = new Random();
    return Enumerable.Range(1, 5).Select(index => new WeatherForecast
    {
        Date = DateTime.Now.AddDays(index),
        TemperatureC = rng.Next(-20, 55),
        Summary = Summaries[rng.Next(Summaries.Length)]
    })
    .ToArray();
}

}

如果我通过 Postman (https://localhost:44337/Incident) 运行请求，我会得到预期的结果 - 五个随机 WeatherForecast 对象，就像 WeatherForecastController 一样。

然后，我创建了一个 razor 页面 Incidents.razor，它与 Blazor 项目创建的 FetchData.razor 页面相同。唯一的区别是我调用“事件”控制器而不是 WeatherForecastController。我只显示差异：

protected override async Task OnInitializedAsync()
{
    forecasts = await Http.GetFromJsonAsync<WeatherForecast[]>("**Incident**");
}

如果我访问 Incidents.razor 页面，我会收到以下异常：

Unhandled exception rendering component: The provided ContentType is not supported; the supported types are 'application/json' and the structured syntax suffix 'application/+json'.
System.NotSupportedException: The provided ContentType is not supported; the supported types are 'application/json' and the structured syntax suffix 'application/+json'.
  at System.Net.Http.Json.HttpContentJsonExtensions.ValidateContent (System.Net.Http.HttpContent content) <0x2ebafb0 + 0x0009a> in <filename unknown>:0 
  at System.Net.Http.Json.HttpContentJsonExtensions.ReadFromJsonAsync[T] (System.Net.Http.HttpContent content, System.Text.Json.JsonSerializerOptions options, System.Threading.CancellationToken cancellationToken) <0x3069af0 + 0x00006> in <filename unknown>:0 
  at System.Net.Http.Json.HttpClientJsonExtensions.GetFromJsonAsyncCore[T] (System.Threading.Tasks.Task`1[TResult] taskResponse, System.Text.Json.JsonSerializerOptions options, System.Threading.CancellationToken cancellationToken) <0x3048af8 + 0x0011c> in <filename unknown>:0 
  at BlazorAuthenticationTest.Client.Pages.Incidents.OnInitializedAsync () [0x00033] in C:\Users\scstoecker\source\repos\BlazorAuthenticationTest\BlazorAuthenticationTest\Client\Pages\Incidents.razor:43 
  at Microsoft.AspNetCore.Components.ComponentBase.RunInitAndSetParametersAsync () <0x2b9a930 + 0x0013a> in <filename unknown>:0 
  at Microsoft.AspNetCore.Components.RenderTree.Renderer.GetErrorHandledTask (System.Threading.Tasks.Task taskToHandle) <0x2dc2a30 + 0x000b6> in <filename unknown>:0

知道为什么只更改控制器名称会导致此 ContentType 异常吗？我已经清理并重建了解决方案。

标签： blazorblazor-webassembly

解决方案

我重新启动并且新控制器工作。唔。我添加了一个新的控制器TestController，再次尝试，同样出现“未处理的异常渲染组件...”错误。我删除了 obj 和 bin 目录并重建，TestController 工作。我想如果我再次看到该特定错误，我只需要重做该过程。

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