C# GraphQL模型与System.Text.Json.JsonException斗争

我创建了一个新的.NET核心项目，并安装了GraphQL、GraphiQL和GraphQL.SystemTextJson包

当运行应用程序时，这就是我得到的

此外，异常消息GraphiQL无法找到架构文档

首先，我有两个实体，用户和任务

public sealed class User
{
    public Guid Id { get; set; }
}

public sealed class Task
{
    public Guid Id { get; set; }
}

它们都有各自的表示图类型

public sealed class UserType : ObjectGraphType<User>
{
    public UserType()
    {
        Name = nameof(User);
        Field(user => user.Id).Description("The user id.");
    }
}

public sealed class TaskType : ObjectGraphType<Task>
{
    public TaskType()
    {
        Name = nameof(Task);
        Field(task => task.Id).Description("The task id.");
    }
}

在

ConfigureServices

的启动文件中，我在调用

services.AddControllers（）

最后，我实现了API控制器

[ApiController]
[Route("[controller]")]
public sealed class GraphQLController : Controller
{
    private readonly ISchema _schema;
    private readonly IDocumentExecuter _documentExecuter;

    public GraphQLController(ISchema schema, IDocumentExecuter documentExecuter)
    {
        _schema = schema;
        _documentExecuter = documentExecuter;
    }

    public async Task<IActionResult> Post([FromBody] GraphQLRequest graphQlRequest)
    {
        ExecutionOptions executionOptions = new ExecutionOptions()
        {
            Schema = _schema,
            Query = graphQlRequest.Query,
            Inputs = graphQlRequest.Variables?.ToInputs()
        };

        ExecutionResult executionResult = await _documentExecuter.ExecuteAsync(executionOptions);

        if (executionResult.Errors != null)
            return BadRequest(executionResult);

        return Ok(executionResult);
    }
}

---

我现在迁移到了.NET5，却收到了这个错误

---

我添加了一个复制库

---

这是Json解析器的经典之作。如果您有导航属性或相互引用的属性

通常，可以通过返回映射结果或调整Json序列化程序设置来修复此问题

我不确定这是否在.Net Core 3.1中修复 但是您可以添加到startup.cs

如果尚未安装，请安装

newtonsoftjson

services
  .AddControllers()
  .AddNewtonsoftJson(options =>
  {
      options.SerializerSettings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore;
  });

希望这能解决问题

这里有一些关于这个问题的文章

---

您在.Net 5中的错误与未注册的图形类型有关。如果在调试设置中启用所有异常并禁用“仅我的代码”，您将看到此错误

System.InvalidOperationException: 'Required service for type API.GraphTypes.UserType not found'
This exception was originally thrown at this call stack:
    GraphQL.Utilities.ServiceProviderExtensions.GetRequiredService(System.IServiceProvider, System.Type) in ServiceProviderExtensions.cs
    GraphQL.Types.Schema.CreateTypesLookup.AnonymousMethod__68_1(System.Type) in Schema.cs
    GraphQL.Types.GraphTypesLookup.Create.AnonymousMethod__0(System.Type) in GraphTypesLookup.cs
    GraphQL.Types.GraphTypesLookup.AddTypeIfNotRegistered(System.Type, GraphQL.Types.TypeCollectionContext) in GraphTypesLookup.cs
    GraphQL.Types.GraphTypesLookup.HandleField(GraphQL.Types.IComplexGraphType, GraphQL.Types.FieldType, GraphQL.Types.TypeCollectionContext, bool) in GraphTypesLookup.cs
    GraphQL.Types.GraphTypesLookup.AddType(GraphQL.Types.IGraphType, GraphQL.Types.TypeCollectionContext) in GraphTypesLookup.cs
    GraphQL.Types.GraphTypesLookup.Create(System.Collections.Generic.IEnumerable<GraphQL.Types.IGraphType>, System.Collections.Generic.IEnumerable<GraphQL.Types.DirectiveGraphType>, System.Func<System.Type, GraphQL.Types.IGraphType>, GraphQL.Conversion.INameConverter, bool) in GraphTypesLookup.cs
    GraphQL.Types.Schema.CreateTypesLookup() in Schema.cs
    System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()

更新后的

GraphQLController.cs

[ApiController]
[Route("[controller]")]
public sealed class GraphQLController : Controller
{
    private readonly ISchema _schema;
    private readonly IDocumentExecuter _documentExecuter;
    private readonly IDocumentWriter _documentWriter;

    public GraphQLController(ISchema schema, IDocumentExecuter documentExecuter, IDocumentWriter documentWriter)
    {
        _schema = schema;
        _documentExecuter = documentExecuter;
        _documentWriter = documentWriter;
    }

    public async Task Post([FromBody] GraphQLRequest graphQlRequest)
    {
        ExecutionOptions executionOptions = new ExecutionOptions()
        {
            Schema = _schema,
            Query = graphQlRequest.Query,
            Inputs = graphQlRequest.Variables?.ToInputs()
        };

        ExecutionResult executionResult = await _documentExecuter.ExecuteAsync(executionOptions);

        await WriteResponseAsync(HttpContext, executionResult);
    }

    private async Task WriteResponseAsync(HttpContext context, ExecutionResult result)
    {
        context.Response.ContentType = "application/json";
        context.Response.StatusCode = result.Errors?.Any() == true ? (int)HttpStatusCode.BadRequest : (int)HttpStatusCode.OK;
    
        await _documentWriter.WriteAsync(context.Response.Body, result);
    }
}

---

graphQlRequest

的值是多少？您可以将其值的json表示添加到您的问题中。OfirD我将值添加到我的问题中：）您可以将完整的Silion上载到Github吗？如果人们可以克隆并玩你的reposure，那么帮助会更容易。给我一个second@Artur你可以在这里找到嘿，谢谢你的回答。不幸的是，我没有使用Newtonsoft。由于Microsoft提供了自己的JSON库，现在我安装了

GraphQL.SystemTextJson

包，正如这里的文档所述，在system.text.JSON由于referenceloop处理错误而不够成熟之前，这是一个已知的问题。强烈建议您要么更新到.net core 5，要么将system.text.json替换为newtonsofts.：）顺便说一句：这里有一个微软自己的文档链接，他们的json序列化程序：即使在3.1版本中，它似乎仍然不支持我迁移到.NET 5的referenceloop errorhmm，但不幸的是仍然出现了一个错误。。（更新了我的问题）我理解您使用Newtonsoft的原因，但我希望避免使用外部软件包作为解决方法……：SSo它不再是referenceloop处理错误。万岁！不幸的是，现在您在system.text.json中遇到了另一个不受支持的功能。例如，看看这个已注册的问题，它说明了与system.text.json引发此异常相同的事实。不过，我最强烈的建议还是改用newtonsoft，它已经存在了很长时间，并且可以完成这项工作。嗯：/谢谢。但我认为我的代码是错误的，因为其他人也使用这个软件包，或者至少有人在发布它之前尝试过它？我建议使用中间件作为使用库的更简单、更干净的方式。看这个例子：是的，错误消失了！但是GraphiQL无法加载架构。。我如何添加它？嗯，在注册缺少的类型并用

IDocumentWriter

将响应写入后，我实际上可以在文档中看到模式。我将用控制器代码更新答案

[ApiController]
[Route("[controller]")]
public sealed class GraphQLController : Controller
{
    private readonly ISchema _schema;
    private readonly IDocumentExecuter _documentExecuter;

    public GraphQLController(ISchema schema, IDocumentExecuter documentExecuter)
    {
        _schema = schema;
        _documentExecuter = documentExecuter;
    }

    public async Task<IActionResult> Post([FromBody] GraphQLRequest graphQlRequest)
    {
        ExecutionOptions executionOptions = new ExecutionOptions()
        {
            Schema = _schema,
            Query = graphQlRequest.Query,
            Inputs = graphQlRequest.Variables?.ToInputs()
        };

        ExecutionResult executionResult = await _documentExecuter.ExecuteAsync(executionOptions);

        if (executionResult.Errors != null)
            return BadRequest(executionResult);

        return Ok(executionResult);
    }
}

query IntrospectionQuery {
  __schema {
    queryType { name }
    mutationType { name }
    subscriptionType { name }
    types {
      ...FullType
    }
    directives {
      name
      description
      locations
      args {
        ...InputValue
      }
    }
  }
}

fragment FullType on __Type {
  kind
  name
  description
  fields(includeDeprecated: true) {
    name
    description
    args {
      ...InputValue
    }
    type {
      ...TypeRef
    }
    isDeprecated
    deprecationReason
  }
  inputFields {
    ...InputValue
  }
  interfaces {
    ...TypeRef
  }
  enumValues(includeDeprecated: true) {
    name
    description
    isDeprecated
    deprecationReason
  }
  possibleTypes {
    ...TypeRef
  }
}

fragment InputValue on __InputValue {
  name
  description
  type { ...TypeRef }
  defaultValue
}

fragment TypeRef on __Type {
  kind
  name
  ofType {
    kind
    name
    ofType {
      kind
      name
      ofType {
        kind
        name
        ofType {
          kind
          name
          ofType {
            kind
            name
            ofType {
              kind
              name
              ofType {
                kind
                name
              }
            }
          }
        }
      }
    }
  }
}

services
  .AddControllers()
  .AddNewtonsoftJson(options =>
  {
      options.SerializerSettings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore;
  });

System.InvalidOperationException: 'Required service for type API.GraphTypes.UserType not found'
This exception was originally thrown at this call stack:
    GraphQL.Utilities.ServiceProviderExtensions.GetRequiredService(System.IServiceProvider, System.Type) in ServiceProviderExtensions.cs
    GraphQL.Types.Schema.CreateTypesLookup.AnonymousMethod__68_1(System.Type) in Schema.cs
    GraphQL.Types.GraphTypesLookup.Create.AnonymousMethod__0(System.Type) in GraphTypesLookup.cs
    GraphQL.Types.GraphTypesLookup.AddTypeIfNotRegistered(System.Type, GraphQL.Types.TypeCollectionContext) in GraphTypesLookup.cs
    GraphQL.Types.GraphTypesLookup.HandleField(GraphQL.Types.IComplexGraphType, GraphQL.Types.FieldType, GraphQL.Types.TypeCollectionContext, bool) in GraphTypesLookup.cs
    GraphQL.Types.GraphTypesLookup.AddType(GraphQL.Types.IGraphType, GraphQL.Types.TypeCollectionContext) in GraphTypesLookup.cs
    GraphQL.Types.GraphTypesLookup.Create(System.Collections.Generic.IEnumerable<GraphQL.Types.IGraphType>, System.Collections.Generic.IEnumerable<GraphQL.Types.DirectiveGraphType>, System.Func<System.Type, GraphQL.Types.IGraphType>, GraphQL.Conversion.INameConverter, bool) in GraphTypesLookup.cs
    GraphQL.Types.Schema.CreateTypesLookup() in Schema.cs
    System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()

private async Task WriteResponseAsync(HttpContext context, ExecutionResult result)
{
    context.Response.ContentType = "application/json";
    context.Response.StatusCode = result.Errors?.Any() == true ? (int)HttpStatusCode.BadRequest : (int)HttpStatusCode.OK;

    await _documentWriter.WriteAsync(context.Response.Body, result);
}

[ApiController]
[Route("[controller]")]
public sealed class GraphQLController : Controller
{
    private readonly ISchema _schema;
    private readonly IDocumentExecuter _documentExecuter;
    private readonly IDocumentWriter _documentWriter;

    public GraphQLController(ISchema schema, IDocumentExecuter documentExecuter, IDocumentWriter documentWriter)
    {
        _schema = schema;
        _documentExecuter = documentExecuter;
        _documentWriter = documentWriter;
    }

    public async Task Post([FromBody] GraphQLRequest graphQlRequest)
    {
        ExecutionOptions executionOptions = new ExecutionOptions()
        {
            Schema = _schema,
            Query = graphQlRequest.Query,
            Inputs = graphQlRequest.Variables?.ToInputs()
        };

        ExecutionResult executionResult = await _documentExecuter.ExecuteAsync(executionOptions);

        await WriteResponseAsync(HttpContext, executionResult);
    }

    private async Task WriteResponseAsync(HttpContext context, ExecutionResult result)
    {
        context.Response.ContentType = "application/json";
        context.Response.StatusCode = result.Errors?.Any() == true ? (int)HttpStatusCode.BadRequest : (int)HttpStatusCode.OK;
    
        await _documentWriter.WriteAsync(context.Response.Body, result);
    }
}