我们有一个 API,它只是将传入的 JSON 文档发布到消息总线,并为每个文档分配一个 GUID。我们正在从 .Net Core 2.2 升级到 3.1,并打算用新System.Text.Json
库替换 NewtonSoft。
我们反序列化传入的文档,将 GUID 分配给其中一个字段,然后在发送到消息总线之前重新序列化。不幸的是,重新序列化失败并出现异常Operation is not valid due to the current state of the object
。
这是一个显示问题的控制器:-
using System;
using System.Net;
using Project.Models;
using Microsoft.AspNetCore.Mvc;
using System.IO;
using System.Text;
using System.Text.Json;
namespace Project.Controllers
{
[Route("api/test")]
public class TestController : Controller
{
private const string JSONAPIMIMETYPE = "application/vnd.api+json";
public TestController()
{
}
[HttpPost("{eventType}")]
public async System.Threading.Tasks.Task<IActionResult> ProcessEventAsync([FromRoute] string eventType)
{
try
{
JsonApiMessage payload;
using (StreamReader reader = new StreamReader(Request.Body, Encoding.UTF8)) {
string payloadString = await reader.ReadToEndAsync();
try {
payload = JsonSerializer.Deserialize<JsonApiMessage>(payloadString);
}
catch (Exception ex) {
return StatusCode((int)HttpStatusCode.BadRequest);
}
}
if ( ! Request.ContentType.Contains(JSONAPIMIMETYPE) )
{
return StatusCode((int)HttpStatusCode.UnsupportedMediaType);
}
Guid messageID = Guid.NewGuid();
payload.Data.Id = messageID.ToString();
// we would send the message here but for this test, just reserialise it
string reserialisedPayload = JsonSerializer.Serialize(payload);
Request.HttpContext.Response.ContentType = JSONAPIMIMETYPE;
return Accepted(payload);
}
catch (Exception ex)
{
return StatusCode((int)HttpStatusCode.InternalServerError);
}
}
}
}
JsonApiMessage 对象的定义如下:-
using System.Text.Json;
using System.Text.Json.Serialization;
namespace Project.Models
{
public class JsonApiMessage
{
[JsonPropertyName("data")]
public JsonApiData Data { get; set; }
[JsonPropertyName("included")]
public JsonApiData[] Included { get; set; }
}
public class JsonApiData
{
[JsonPropertyName("type")]
public string Type { get; set; }
[JsonPropertyName("id")]
public string Id { get; set; }
[JsonPropertyName("attributes")]
public JsonElement Attributes { get; set; }
[JsonPropertyName("meta")]
public JsonElement Meta { get; set; }
[JsonPropertyName("relationships")]
public JsonElement Relationships { get; set; }
}
}
一个示例调用如下所示:-
POST http://localhost:5000/api/test/event
Content-Type: application/vnd.api+json; charset=UTF-8
{
"data": {
"type": "test",
"attributes": {
"source": "postman",
"instance": "jg",
"level": "INFO",
"message": "If this comes back with an ID, the API is probably working"
}
}
}
当我payload
在 Visual Studio 中检查断点处的内容时,它在顶层看起来不错,但这些JsonElement
位看起来不透明,所以我不知道它们是否已被正确解析。它们的结构可以变化,所以我们只关心它们是有效的 JSON。在旧的 NewtonSoft 版本中,它们是JObject
s。
添加 GUID 后,它会在断点检查时出现在payload
对象中,但我怀疑该问题与对象中的其他元素为只读或类似内容有关。