I've build a very simple, vanilla minimal API with .NET 6. All I'm trying to do for now is prove that I can receive HTTP POST requests and log them. Hopefully if I can get this working I'll start doing something more interesting, but even this vanilla out of the box functionality isn't working.
Some things I've tried:
My full code is posted below, can anyone see what is wrong with this? Or how to fix it?
My minimal 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;}
}
My post message (testing from Postman, but also tried sending from various other places):
{
"LogMessage":"test"
}
The result:
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)
Same result if I try from the Swagger page.
Results.Accepted is a method so you need to invoke it:
app.MapPost("/", (logMessage message) =>
{
...
return Results.Accepted();
});
Otherwise it is converted to delegate (Func<string, object, IResult> in this case) which can not be serialized (so you see the exception in question).
This is how I changed your code and now it works
app.MapPost("/", (logMessage message) =>
{
Console.WriteLine($"[{DateTime.Now.ToShortDateString()}] Received
message:");
Console.WriteLine(message.LogMessage);
return logMessage.GetResult();
});
And then
public class logMessage
{
public static IResult GetResult()
{
return Results.Accepted("");
}
public string? LogMessage { get; set; }
}