.net-core - 将 JsonPatchDocument 与 Blazor 一起使用时出现意外错误
问题描述
我正在使用 Blazor WebAssembly (WASM) 客户端通过 .NET Core REST API 执行更新。为此,我JsonPatchDocument<T>
通过 HTTP PATCH 请求发送一个,其中T
是我的应用程序的数据传输对象 (DTO) 之一。
它不工作。我在 Blazor 应用程序中返回 500 内部服务器错误状态代码。我在 Postman 中得到了更多细节,但不足以让我理解这个问题。
这是我的 Blazor WASM 应用程序中的调用代码:
@code
{
[Parameter]
public int BookId { get; set; } = 101;
private async Task HandleClickAsync()
{
string newTitle = "How to make JsonPatchDocument work with Blazor - Second Edition";
var patchDocument = new JsonPatchDocument<Book>()
.Replace(c => c.Title, newTitle);
var json = JsonSerializer.Serialize(patchDocument);
var content = new StringContent(json, Encoding.UTF8, "application/json-patch+json");
var response = await HttpClient.PatchAsync($"https://localhost:44367/api/books/{BookId}", content);
if (response.IsSuccessStatusCode)
{
// Handle success
}
else if (response.StatusCode == HttpStatusCode.NotFound)
{
// Handle not found
}
else
{
// Handle unexpected failures
}
}
}
这是我的控制器方法:
[ApiController]
[Route("api/[controller]")]
public class BooksController : ControllerBase
{
[HttpPatch("{id:int}")]
public async Task<ActionResult> PatchAsync(
int id,
[FromBody] JsonPatchDocument<Book> patch)
{
// We're just going to fake an asynchronous database call and return a 200 status code to the client
await Task.FromResult(true);
return Ok();
}
}
这是我的 DTO:
public class Book
{
public int Id { get; set; }
public string Title { get; set; }
}
我发送的补丁文档,当序列化为 JSON 时,如下所示:
{"Operations":[{"value":"How to make JsonPatchDocument work with Blazor - Second Edition","OperationType":2,"path":"/Title","op":"replace","from":null}],"ContractResolver":{}}
我在 Postman 中看到的错误详细信息是:
System.NotSupportedException: Deserialization of interface types is not supported. Type 'Newtonsoft.Json.Serialization.IContractResolver'
at System.Text.Json.ThrowHelper.ThrowNotSupportedException_DeserializeCreateObjectDelegateIsNull(Type invalidType)
at System.Text.Json.JsonSerializer.HandleStartObject(JsonSerializerOptions options, ReadStack& state)
at System.Text.Json.JsonSerializer.ReadCore(JsonSerializerOptions options, Utf8JsonReader& reader, ReadStack& readStack)
at System.Text.Json.JsonSerializer.ReadCore(JsonReaderState& readerState, Boolean isFinalBlock, ReadOnlySpan`1 buffer, JsonSerializerOptions options, ReadStack& readStack)
at System.Text.Json.JsonSerializer.ReadAsync[TValue](Stream utf8Json, Type returnType, JsonSerializerOptions options, CancellationToken cancellationToken)
at Microsoft.AspNetCore.Mvc.Formatters.SystemTextJsonInputFormatter.ReadRequestBodyAsync(InputFormatterContext context, Encoding encoding)
at Microsoft.AspNetCore.Mvc.Formatters.SystemTextJsonInputFormatter.ReadRequestBodyAsync(InputFormatterContext context, Encoding encoding)
at Microsoft.AspNetCore.Mvc.ModelBinding.Binders.BodyModelBinder.BindModelAsync(ModelBindingContext bindingContext)
at Microsoft.AspNetCore.Mvc.ModelBinding.ParameterBinder.BindModelAsync(ActionContext actionContext, IModelBinder modelBinder, IValueProvider valueProvider, ParameterDescriptor parameter, ModelMetadata metadata, Object value)
at Microsoft.AspNetCore.Mvc.Controllers.ControllerBinderDelegateProvider.<>c__DisplayClass0_0.<<CreateBinderDelegate>g__Bind|0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.<InvokeInnerFilterAsync>g__Awaited|13_0(ControllerActionInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResourceFilter>g__Awaited|24_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResourceExecutedContextSealed context)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeFilterPipelineAsync()
--- End of stack trace from previous location where exception was thrown ---
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
at Microsoft.AspNetCore.Builder.Extensions.MapWhenMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.Builder.Extensions.MapMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)
HEADERS
=======
Accept: */*
Accept-Encoding: gzip, deflate, br
Cache-Control: no-cache
Connection: keep-alive
Content-Length: 175
Content-Type: application/json
Host: localhost:44367
User-Agent: PostmanRuntime/7.26.3
Postman-Token: b4444f41-b80f-4ef5-92d5-2416d68d471e
我的项目都没有直接依赖于 Newtonsoft。我不知道我引用的 Microsoft 库是否依赖于 Newtonsoft。该错误表明他们可能会这样做。
可以在 GitHub 上的这个小存储库中观察到这种行为: https ://github.com/BenjaminCharlton/JsonPatchDocumentWithBlazor
请问有人知道为什么它不起作用和/或什么会解决它吗?
谢谢
解决方案
我设法解决了这个困难,Pavel 和 Enet 的意见很有用,谢谢。
对于遇到相同问题的其他人,以下是您需要了解的解决方法:
截至目前(2020 年末),将 .NET Core 从迁移到 .NET Core 的努力尚未
Newtonsoft.Json
完成System.Text.Json
。该软件包Microsoft.AspNetCore.JsonPatch
仍然依赖于Newtonsoft.Json
..NET Core 开发团队意识到 GitHub 报告了很多问题。但他们都被关闭了,没有采取任何行动。显然,切换
Microsoft.AspNetCore.JsonPatch
到System.Text.Json
.要将 Newtonsoft 用于
JsonPatch
es 而不是其他任何东西,这里描述了一个不错的小技巧,您应该在Startup
Web API/服务器项目的类中使用它。特别注意GetJsonPatchInputFormatter
里面调用的helper方法的使用Startup.ConfigureServices
但这本身可能无法解决您的 Blazor WASM/客户端项目将收到的 50X 和 40X HTTP 错误,因为如果您序列化您的
JsonPatch
使用System.Text.Json
,它会在 JSON 字符串的末尾添加一个空ContractResolver
对象(看起来像,"ContractResolver":{}
),这在服务器端中断。由于某种原因,该请求与您所做的任何控制器路由都不匹配。要解决此问题,您还必须
Newtonsoft.Json
在 Blazor 客户端上使用。您不必将它用于所有事情;你只需要用它来序列化你所有的JsonPatch
es。它的代码行数Newtonsoft.Json
比它多几行,System.Text.Json
但我做了一个扩展方法,所以它不会在所有地方重复。扩展方法如下所示:public static class HttpClientExtensions { public static async Task<HttpResponseMessage> PatchAsync<T>(this HttpClient client, string requestUri, JsonPatchDocument<T> patchDocument) where T : class { var writer = new StringWriter(); var serializer = new JsonSerializer(); serializer.Serialize(writer, patchDocument); var json = writer.ToString(); var content = new StringContent(json, Encoding.UTF8, "application/json-patch+json"); return await client.PatchAsync(requestUri, content); }
}
就是这样。这种解决方法对我有用,我希望它也对你有用。
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