Asp.net core .net核心GraphQL，GraphQL.SystemTextJson:x27的序列化和反序列化；系统类型'；实例不受支持

在ASP.NET core 5应用程序中，我将GraphQL与GraphQL.SystemTextJson一起使用。 当我尝试返回结果时，我得到s System.NotSupportedException，它说“不支持对'System.Type'实例的序列化和反序列化，应该避免，因为它们可能导致安全问题。”

我怀疑DocumentWriter的配置中缺少某些内容

它在ConfigureServices中的配置如下：

    public void ConfigureServices(IServiceCollection services)
    {

        services.AddControllers();

        ...

        services.AddScoped<IDocumentWriter, DocumentWriter>();

        services.AddControllers()
            .AddJsonOptions(options =>
            {
                options.JsonSerializerOptions.WriteIndented = true;
                options.JsonSerializerOptions.Converters.Add(new CustomJsonConverterForType());
            });

---

我解决了创建自定义JsonConverter的问题：

public class CustomJsonConverterForType : JsonConverter<Type>
{
    public override Type Read(
        ref Utf8JsonReader reader,
        Type typeToConvert,
        JsonSerializerOptions options
        )
    {
        // Caution: Deserialization of type instances like this 
        // is not recommended and should be avoided
        // since it can lead to potential security issues.

        // If you really want this supported (for instance if the JSON input is trusted):
        // string assemblyQualifiedName = reader.GetString();
        // return Type.GetType(assemblyQualifiedName);
        throw new NotSupportedException();
    }

    public override void Write(
        Utf8JsonWriter writer,
        Type value,
        JsonSerializerOptions options
        )
    {
        string assemblyQualifiedName = value.AssemblyQualifiedName;
        // Use this with caution, since you are disclosing type information.
        writer.WriteStringValue(assemblyQualifiedName);
    }
}

---

我通过使用文档中显示的代码片段修复了该问题：

[HttpPost]
公共异步任务Post（[FromBody]GraphQLQueryTo查询）
{
var result=wait\u execute.ExecuteAsync（\u=>
{
_.Schema=_Schema；
_.Query=Query.Query；
_.Inputs=query.Variables？.ToInputs（）；
});
/*--------增加了这个---------------------------------*/
HttpContext.Response.ContentType=“应用程序/json”；
HttpContext.Response.StatusCode=200；//确定
var writer=new GraphQL.SystemTextJson.DocumentWriter（）；
wait writer.WriteAsync（HttpContext.Response.Body，result）*
/* ------------------------------------------------------*/
如果（结果错误？.Count>0）
{
返回请求（）；
}
返回Ok（结果数据）；
}
}

您的代码中是否有DataSet或DataTable？你可以研究这个问题。也许这就是原因。不管怎么说，我认为没有更多的细节，很难说出具体的东西details@AndrewSilver，我既不使用DataSet，也不使用DataTable。为了完整起见，我更新了问题，报告了整个代码。是的。这实际上解决了问题。小问题：方法应该返回任务；代码段应该是：HttpContext.Response.ContentType=“application/json”；HttpContext.Response.StatusCode=result.Errors？.Any（）==true？（int）HttpStatusCode.BadRequest：（int）HttpStatusCode.OK；var writer=new GraphQL.SystemTextJson.DocumentWriter（）；但是，应该没有代码，我希望DocumentWriter按照ConfigureServices中的定义被注入。我想您可以将其注入控制器中。显然，您必须明确地调用DocumentWriter.Write，而所有的文档都让人相信它隐含在对DocumentExecutor的调用中。

public class CustomJsonConverterForType : JsonConverter<Type>
{
    public override Type Read(
        ref Utf8JsonReader reader,
        Type typeToConvert,
        JsonSerializerOptions options
        )
    {
        // Caution: Deserialization of type instances like this 
        // is not recommended and should be avoided
        // since it can lead to potential security issues.

        // If you really want this supported (for instance if the JSON input is trusted):
        // string assemblyQualifiedName = reader.GetString();
        // return Type.GetType(assemblyQualifiedName);
        throw new NotSupportedException();
    }

    public override void Write(
        Utf8JsonWriter writer,
        Type value,
        JsonSerializerOptions options
        )
    {
        string assemblyQualifiedName = value.AssemblyQualifiedName;
        // Use this with caution, since you are disclosing type information.
        writer.WriteStringValue(assemblyQualifiedName);
    }
}

        services.AddControllers()
            .AddJsonOptions(options =>
            {
                options.JsonSerializerOptions.WriteIndented = true;
                options.JsonSerializerOptions.Converters.Add(new CustomJsonConverterForType());
            });

[HttpPost]
public async Task<IActionResult> Post([FromBody] GraphQLQueryDTO query)
{
  var result = await _executer.ExecuteAsync(_ =>
  {
     _.Schema = _schema;
     _.Query = query.Query;
     _.Inputs = query.Variables?.ToInputs();
  });

  /* ----------- Added this ---------------------------------*/
  HttpContext.Response.ContentType = "application/json";
  HttpContext.Response.StatusCode = 200; // OK
  var writer = new GraphQL.SystemTextJson.DocumentWriter();
  await writer.WriteAsync(HttpContext.Response.Body, result);*
  /* ------------------------------------------------------*/

  if (result.Errors?.Count > 0)
  {
    return BadRequest();
  }
    return Ok(result.Data);
  }
}