为什么我的 .NET 6 Minimal API 不能反序列化 POST 正文？

Question

我用 .NET 6 构建了一个非常简单的 vanilla minimal API。我现在想做的就是证明我可以接收 HTTP POST 请求并记录它们.希望如果我能让它工作，我会开始做一些更有趣的事情，但即使是这种开箱即用的香草功能也不起作用。

我尝试过的一些事情：

正在将我的 logMessage 更改为记录
向 logMessage 添加默认构造函数

我的完整代码在下面 posted，有人能看出这有什么问题吗？或者如何解决？

我的最小值API：

using Microsoft.AspNetCore.Http.Json;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();

// NOTE: tried the below but it made no difference. Commented back out.
// builder.Services.Configure<JsonOptions>(options =>
// {
//     options.SerializerOptions.IncludeFields = true;
// });


var app = builder.Build();

// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI();
}

app.UseHttpsRedirection();

var summaries = new[]
{
    "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
};

app.MapGet("/weatherforecast", () =>
{
    var forecast = Enumerable.Range(1, 5).Select(index =>
       new WeatherForecast
       (
           DateTime.Now.AddDays(index),
           Random.Shared.Next(-20, 55),
           summaries[Random.Shared.Next(summaries.Length)]
       ))
        .ToArray();
    return forecast;
})
.WithName("GetWeatherForecast");

app.MapPost("/", (logMessage message) => 
{
    Console.WriteLine($"[{DateTime.Now.ToShortDateString()}] Received message:");
    Console.WriteLine(message.LogMessage);
    return Results.Accepted;
});

app.Run("http://localhost:5025");

internal record WeatherForecast(DateTime Date, int TemperatureC, string? Summary)
{
    public int TemperatureF => 32 + (int)(TemperatureC / 0.5556);
}

public class logMessage
{
    public string? LogMessage {get;set;}
}

我的 post 消息（从 Postman 测试，但也尝试从其他地方发送）：

{
    "LogMessage":"test"
}

结果：

System.NotSupportedException: Serialization and deserialization of 'System.Type' instances are not supported. Path: $.Method.ReturnParameter.Member.DeclaringType.
 ---> System.NotSupportedException: Serialization and deserialization of 'System.Type' instances are not supported.
   at System.Text.Json.Serialization.Converters.UnsupportedTypeConverter`1.Write(Utf8JsonWriter writer, T value, JsonSerializerOptions options)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.Metadata.JsonPropertyInfo`1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer)
   at System.Text.Json.Serialization.Converters.ObjectDefaultConverter`1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.Metadata.JsonPropertyInfo`1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer)
   at System.Text.Json.Serialization.Converters.ObjectDefaultConverter`1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.Metadata.JsonPropertyInfo`1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer)
   at System.Text.Json.Serialization.Converters.ObjectDefaultConverter`1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.Metadata.JsonPropertyInfo`1.GetMemberAndWriteJson(Object obj, WriteStack& state, Utf8JsonWriter writer)
   at System.Text.Json.Serialization.Converters.ObjectDefaultConverter`1.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   --- End of inner exception stack trace ---
   at System.Text.Json.ThrowHelper.ThrowNotSupportedException(WriteStack& state, NotSupportedException ex)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCoreAsObject(Utf8JsonWriter writer, Object value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteCore[TValue](JsonConverter jsonConverter, Utf8JsonWriter writer, TValue& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteStreamAsync[TValue](Stream utf8Json, TValue value, JsonTypeInfo jsonTypeInfo, CancellationToken cancellationToken)
   at System.Text.Json.JsonSerializer.WriteStreamAsync[TValue](Stream utf8Json, TValue value, JsonTypeInfo jsonTypeInfo, CancellationToken cancellationToken)
   at System.Text.Json.JsonSerializer.WriteStreamAsync[TValue](Stream utf8Json, TValue value, JsonTypeInfo jsonTypeInfo, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.Http.HttpResponseJsonExtensions.WriteAsJsonAsyncSlow[TValue](Stream body, TValue value, JsonSerializerOptions options, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.Http.RequestDelegateFactory.<>c__DisplayClass46_3.<<HandleRequestBodyAndCompileRequestDelegate>b__2>d.MoveNext()
--- End of stack trace from previous location ---
   at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
   at Swashbuckle.AspNetCore.SwaggerUI.SwaggerUIMiddleware.Invoke(HttpContext httpContext)
   at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.Invoke(HttpContext httpContext, ISwaggerProvider swaggerProvider)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

如果我从 Swagger 页面尝试，结果相同。

Answer 1

Results.Accepted 是一个方法所以你需要调用它：

app.MapPost("/", (logMessage message) => 
{
    ...
    return Results.Accepted();
});

否则它会被转换为无法序列化的委托（在本例中为Func<string, object, IResult>）（因此您会看到有问题的异常）。

Answer 2

这就是我更改您的代码的方式，现在可以使用了

app.MapPost("/", (logMessage message) =>
 {
   Console.WriteLine($"[{DateTime.Now.ToShortDateString()}] Received 
   message:");
   Console.WriteLine(message.LogMessage);
   return logMessage.GetResult();
});

然后

 public class logMessage
  {
    public static IResult GetResult()
    {
      return Results.Accepted("");
    }
    public string? LogMessage { get; set; }
  }

为什么我的 .NET 6 Minimal API 不能反序列化 POST 正文？

Why can't my .NET 6 Minimal API deserialize POST body?

.net

c#

json

swashbuckle