测试分段文件上传 Azure 函数
Testing a Multipart file upload Azure Function
所以我编写了一个简单的 Azure 函数 (AF)，它接受（通过 Http Post 方法）IFormCollection，遍历文件 collection，将每个文件推送到 Azure Blob 存储容器中returns url 每个文件。
当我使用 'multipart/form-data' header 通过 Postman 处理单个文件或多个文件 post 时，该功能本身完美运行。但是，当我尝试通过 xUnit 测试 post 文件时，出现以下错误：
System.IO.InvalidDataException：多部分 body 超过长度限制 16384。
我四处寻找解决方案，尝试了不同的方法，即；
- 正在复制请求 object 以尽可能接近 Post 人的请求。
- 在 header 中玩弄 'boundary'。
- 在函数上设置 'RequestFormLimits'。
到目前为止，None 个已提供帮助。
具体项目如下：
Azure Function v3: 目标 .netcoreapp3.1
Startup.cs
public class Startup : FunctionsStartup
{
public IConfiguration Configuration { get; private set; }
public override void Configure(IFunctionsHostBuilder builder)
{
var x = builder;
InitializeConfiguration(builder);
builder.Services.AddSingleton(Configuration.Get<UploadImagesAppSettings>());
builder.Services.AddLogging();
builder.Services.AddSingleton<IBlobService,BlobService>();
}
private void InitializeConfiguration(IFunctionsHostBuilder builder)
{
var executionContextOptions = builder
.Services
.BuildServiceProvider()
.GetService<IOptions<ExecutionContextOptions>>()
.Value;
Configuration = new ConfigurationBuilder()
.SetBasePath(executionContextOptions.AppDirectory)
.AddJsonFile("appsettings.json")
.AddJsonFile("appsettings.Development.json", optional: true)
.AddEnvironmentVariables()
.Build();
}
}
UploadImages.cs
public class UploadImages
{
private readonly IBlobService BlobService;
public UploadImages(IBlobService blobService)
{
BlobService = blobService;
}
[FunctionName("UploadImages")]
[RequestFormLimits(ValueLengthLimit = int.MaxValue,
MultipartBodyLengthLimit = 60000000, ValueCountLimit = 10)]
public async Task<IActionResult> Run(
[HttpTrigger(AuthorizationLevel.Function, "get", "post", Route = "images")] HttpRequest req)
{
List<Uri> returnUris = new List<Uri>();
if (req.ContentLength == 0)
{
string badResponseMessage = $"Request has no content";
return new BadRequestObjectResult(badResponseMessage);
}
if (req.ContentType.Contains("multipart/form-data") && req.Form.Files.Count > 0)
{
foreach (var file in req.Form.Files)
{
if (!file.IsValidImage())
{
string badResponseMessage = $"{file.FileName} is not a valid/accepted Image file";
return new BadRequestObjectResult(badResponseMessage);
}
var uri = await BlobService.CreateBlobAsync(file);
if (uri == null)
{
return new ObjectResult($"Could not blob the file {file.FileName}.");
}
returnUris.Add(uri);
}
}
if (!returnUris.Any())
{
return new NoContentResult();
}
return new OkObjectResult(returnUris);
}
}
异常抛出：
当上面的第二个 if 语句试图处理 req.Form.Files.Count > 0 时抛出以下异常，即
if (req.ContentType.Contains("multipart/form-data") && req.Form.Files.Count > 0) {}
Message:
System.IO.InvalidDataException : Multipart body length limit 16384 exceeded.
Stack Trace:
MultipartReaderStream.UpdatePosition(Int32 read)
MultipartReaderStream.ReadAsync(Byte[] buffer, Int32 offset, Int32 count, CancellationToken cancellationToken)
StreamHelperExtensions.DrainAsync(Stream stream, ArrayPool`1 bytePool, Nullable`1 limit, CancellationToken cancellationToken)
MultipartReader.ReadNextSectionAsync(CancellationToken cancellationToken)
FormFeature.InnerReadFormAsync(CancellationToken cancellationToken)
FormFeature.ReadForm()
DefaultHttpRequest.get_Form()
UploadImages.Run(HttpRequest req) line 42
UploadImagesTests.HttpTrigger_ShouldReturnListOfUploadedUris(String fileNames)
xUnit 测试项目： 目标 .netcoreapp3.1
转到 xUnit 测试项目，基本上我正在尝试编写集成测试。该项目引用了 AF 项目并具有以下 classes:
TestHost.cs
public class TestHost
{
public TestHost()
{
var startup = new TestStartup();
var host = new HostBuilder()
.ConfigureWebJobs(startup.Configure)
.ConfigureServices(ReplaceTestOverrides)
.Build();
ServiceProvider = host.Services;
}
public IServiceProvider ServiceProvider { get; }
private void ReplaceTestOverrides(IServiceCollection services)
{
// services.Replace(new ServiceDescriptor(typeof(ServiceToReplace), testImplementation));
}
private class TestStartup : Startup
{
public override void Configure(IFunctionsHostBuilder builder)
{
SetExecutionContextOptions(builder);
base.Configure(builder);
}
private static void SetExecutionContextOptions(IFunctionsHostBuilder builder)
{
builder.Services.Configure<ExecutionContextOptions>(o => o.AppDirectory = Directory.GetCurrentDirectory());
}
}
}
TestCollection.cs
[CollectionDefinition(Name)]
public class TestCollection : ICollectionFixture<TestHost>
{
public const string Name = nameof(TestCollection);
}
HttpRequestFactory.cs: 创建 Http Post 请求
public static class HttpRequestFactory
{
public static DefaultHttpRequest Create(string method, string contentType, Stream body)
{
var request = new DefaultHttpRequest(new DefaultHttpContext());
var contentTypeWithBoundary = new MediaTypeHeaderValue(contentType)
{
Boundary = $"----------------------------{DateTime.Now.Ticks.ToString("x")}"
};
var boundary = MultipartRequestHelper.GetBoundary(
contentTypeWithBoundary, (int)body.Length);
request.Method = method;
request.Headers.Add("Cache-Control", "no-cache");
request.Headers.Add("Content-Type", contentType);
request.ContentType = $"{contentType}; boundary={boundary}";
request.ContentLength = body.Length;
request.Body = body;
return request;
}
private static string GetBoundary(MediaTypeHeaderValue contentType, int lengthLimit)
{
var boundary = HeaderUtilities.RemoveQuotes(contentType.Boundary);
if (string.IsNullOrWhiteSpace(boundary.Value))
{
throw new InvalidDataException("Missing content-type boundary.");
}
if (boundary.Length > lengthLimit)
{
throw new InvalidDataException(
$"Multipart boundary length limit {lengthLimit} exceeded.");
}
return boundary.Value;
}
}
The MultipartRequestHelper.cs class is available here
最后测试 class:
[Collection(TestCollection.Name)]
public class UploadImagesTests
{
readonly UploadImages UploadImagesFunction;
public UploadImagesTests(TestHost testHost)
{
UploadImagesFunction = new UploadImages(testHost.ServiceProvider.GetRequiredService<IBlobService>());
}
[Theory]
[InlineData("testfile2.jpg")]
public async void HttpTrigger_ShouldReturnListOfUploadedUris(string fileNames)
{
var formFile = GetFormFile(fileNames);
var fileStream = formFile.OpenReadStream();
var request = HttpRequestFactory.Create("POST", "multipart/form-data", fileStream);
var response = (OkObjectResult)await UploadImagesFunction.Run(request);
//fileStream.Close();
Assert.True(response.StatusCode == StatusCodes.Status200OK);
}
private static IFormFile GetFormFile(string fileName)
{
string fileExtension = fileName.Substring(fileName.IndexOf('.') + 1);
string fileNameandPath = GetFilePathWithName(fileName);
IFormFile formFile;
var stream = File.OpenRead(fileNameandPath);
switch (fileExtension)
{
case "jpg":
formFile = new FormFile(stream, 0, stream.Length,
fileName.Substring(0, fileName.IndexOf('.')),
fileName)
{
Headers = new HeaderDictionary(),
ContentType = "image/jpeg"
};
break;
case "png":
formFile = new FormFile(stream, 0, stream.Length,
fileName.Substring(0, fileName.IndexOf('.')),
fileName)
{
Headers = new HeaderDictionary(),
ContentType = "image/png"
};
break;
case "pdf":
formFile = new FormFile(stream, 0, stream.Length,
fileName.Substring(0, fileName.IndexOf('.')),
fileName)
{
Headers = new HeaderDictionary(),
ContentType = "application/pdf"
};
break;
default:
formFile = null;
break;
}
return formFile;
}
private static string GetFilePathWithName(string filename)
{
var outputFolder = Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().Location);
return $"{outputFolder.Substring(0, outputFolder.IndexOf("bin"))}testfiles\{filename}";
}
}
测试似乎命中了函数，req.ContentLength确实有一个值。考虑到这一点，它是否与文件流的管理方式有关？也许方法不对？
如有任何意见，我们将不胜感激。
谢谢
更新 1
根据 post，我还尝试在 Azure 函数启动时设置 ValueLengthLimit 和 MultipartBodyLengthLimit and/or 测试项目而不是 Azure 函数上的属性.然后异常更改为：
“内部流位置意外改变”
在此之后，我再将测试项目中的fileStream位置设置为SeekOrigin.Begin。我开始遇到同样的错误：
“多部分 body 超出长度限制 16384。”
我骑了 50 公里的自行车，睡了个好觉，但我终于想通了:-)。
Azure 函数 (AF) 接受一个名为 'req' 的 HttpRequest 对象作为参数，即
public 异步任务 运行(
[HttpTrigger(AuthorizationLevel.Function, "get", "post", Route = "images")] HttpRequest req)
HttpRequest 对象中文件对象的层次结构（连同参数名称）如下：
- HttpRequest -> 请求
- FormCollection -> 表单
- FormFileCollection -> 文件
这是 AF 接受的内容，可以使用 req.Form.Files
访问文件集合
在我的测试用例中，我没有 posting 一个 FormCollection 对象，而是试图 post 一个文件流到 Azure 函数。
var formFile = GetFormFile(fileNames);
var fileStream = formFile.OpenReadStream();
var request = HttpRequestFactory.Create("POST", "multipart/form-data", fileStream);
因此，req.Form 有一个无法解释的 Stream 值，req.Form.Files 引发异常。
为了纠正这个问题，我必须执行以下操作：
- 还原作为更新 1 的一部分所做的所有更改。这意味着我从启动文件中删除了 'RequestFormLimits' 设置，并将它们作为函数 运行 方法的属性保留。
- 实例化 FormFileCollection 对象并向其添加 IFormFile
- 使用此 FormFileCollection 作为参数实例化 FormCollection 对象。
- 将 FormCollection 添加到请求对象。
为了实现上述目标，我不得不对代码进行以下更改。
在 HttpRequestFactory
中更改 'Create' 方法
public static DefaultHttpRequest Create(string method, string contentType, FormCollection formCollection)
{
var request = new DefaultHttpRequest(new DefaultHttpContext());
var boundary = $"----------------------------{DateTime.Now.Ticks.ToString("x")}";
request.Method = method;
request.Headers.Add("Cache-Control", "no-cache");
request.Headers.Add("Content-Type", contentType);
request.ContentType = $"{contentType}; boundary={boundary}";
request.Form = formCollection;
return request;
}
添加私有静态 GetFormFiles() 方法
我编写了一个额外的 GetFormFiles() 方法，它调用现有的 GetFormFile() 方法，实例化一个 FormFileCollection 对象并将 IFormFile 添加到它。这个方法又returns一个FormFileCollection.
private static FormFileCollection GetFormFiles(string fileNames)
{
var formFileCollection = new FormFileCollection();
foreach (var file in fileNames.Split(','))
{
formFileCollection.Add(GetFormFile(file));
}
return formFileCollection;
}
更改测试方法
测试方法调用GetFormFiles()获取一个FormFileCollection然后
使用此 FormFileCollection 作为参数实例化 FormCollection 对象，然后将 FormCollection 对象作为参数传递给 HttpRequest 对象，而不是传递 Stream。
[Theory]
[InlineData("testfile2.jpg")]
public async void HttpTrigger_ShouldReturnListOfUploadedUris(string fileNames)
{
var formFiles = GetFormFiles(fileNames);
var formCollection = new FormCollection(null, formFiles);
var request = HttpRequestFactory.Create("POST", "multipart/form-data", formCollection);
var response = (OkObjectResult) await UploadImagesFunction.Run(request);
Assert.True(response.StatusCode == StatusCodes.Status200OK);
}
所以最终问题不在于 'RequestFormLimits'，而在于我在 POST 消息中提交的数据类型。
我希望这个答案能为遇到相同错误消息的人提供不同的视角。
干杯。
所以我编写了一个简单的 Azure 函数 (AF)，它接受（通过 Http Post 方法）IFormCollection，遍历文件 collection，将每个文件推送到 Azure Blob 存储容器中returns url 每个文件。
当我使用 'multipart/form-data' header 通过 Postman 处理单个文件或多个文件 post 时，该功能本身完美运行。但是，当我尝试通过 xUnit 测试 post 文件时，出现以下错误：
System.IO.InvalidDataException：多部分 body 超过长度限制 16384。
我四处寻找解决方案，尝试了不同的方法，即；
- 正在复制请求 object 以尽可能接近 Post 人的请求。
- 在 header 中玩弄 'boundary'。
- 在函数上设置 'RequestFormLimits'。
None 个已提供帮助。
具体项目如下：
Azure Function v3: 目标 .netcoreapp3.1
Startup.cs
public class Startup : FunctionsStartup
{
public IConfiguration Configuration { get; private set; }
public override void Configure(IFunctionsHostBuilder builder)
{
var x = builder;
InitializeConfiguration(builder);
builder.Services.AddSingleton(Configuration.Get<UploadImagesAppSettings>());
builder.Services.AddLogging();
builder.Services.AddSingleton<IBlobService,BlobService>();
}
private void InitializeConfiguration(IFunctionsHostBuilder builder)
{
var executionContextOptions = builder
.Services
.BuildServiceProvider()
.GetService<IOptions<ExecutionContextOptions>>()
.Value;
Configuration = new ConfigurationBuilder()
.SetBasePath(executionContextOptions.AppDirectory)
.AddJsonFile("appsettings.json")
.AddJsonFile("appsettings.Development.json", optional: true)
.AddEnvironmentVariables()
.Build();
}
}
UploadImages.cs
public class UploadImages
{
private readonly IBlobService BlobService;
public UploadImages(IBlobService blobService)
{
BlobService = blobService;
}
[FunctionName("UploadImages")]
[RequestFormLimits(ValueLengthLimit = int.MaxValue,
MultipartBodyLengthLimit = 60000000, ValueCountLimit = 10)]
public async Task<IActionResult> Run(
[HttpTrigger(AuthorizationLevel.Function, "get", "post", Route = "images")] HttpRequest req)
{
List<Uri> returnUris = new List<Uri>();
if (req.ContentLength == 0)
{
string badResponseMessage = $"Request has no content";
return new BadRequestObjectResult(badResponseMessage);
}
if (req.ContentType.Contains("multipart/form-data") && req.Form.Files.Count > 0)
{
foreach (var file in req.Form.Files)
{
if (!file.IsValidImage())
{
string badResponseMessage = $"{file.FileName} is not a valid/accepted Image file";
return new BadRequestObjectResult(badResponseMessage);
}
var uri = await BlobService.CreateBlobAsync(file);
if (uri == null)
{
return new ObjectResult($"Could not blob the file {file.FileName}.");
}
returnUris.Add(uri);
}
}
if (!returnUris.Any())
{
return new NoContentResult();
}
return new OkObjectResult(returnUris);
}
}
异常抛出：
当上面的第二个 if 语句试图处理 req.Form.Files.Count > 0 时抛出以下异常，即
if (req.ContentType.Contains("multipart/form-data") && req.Form.Files.Count > 0) {}
Message:
System.IO.InvalidDataException : Multipart body length limit 16384 exceeded.
Stack Trace:
MultipartReaderStream.UpdatePosition(Int32 read)
MultipartReaderStream.ReadAsync(Byte[] buffer, Int32 offset, Int32 count, CancellationToken cancellationToken)
StreamHelperExtensions.DrainAsync(Stream stream, ArrayPool`1 bytePool, Nullable`1 limit, CancellationToken cancellationToken)
MultipartReader.ReadNextSectionAsync(CancellationToken cancellationToken)
FormFeature.InnerReadFormAsync(CancellationToken cancellationToken)
FormFeature.ReadForm()
DefaultHttpRequest.get_Form()
UploadImages.Run(HttpRequest req) line 42
UploadImagesTests.HttpTrigger_ShouldReturnListOfUploadedUris(String fileNames)
xUnit 测试项目： 目标 .netcoreapp3.1
转到 xUnit 测试项目，基本上我正在尝试编写集成测试。该项目引用了 AF 项目并具有以下 classes:
TestHost.cs
public class TestHost
{
public TestHost()
{
var startup = new TestStartup();
var host = new HostBuilder()
.ConfigureWebJobs(startup.Configure)
.ConfigureServices(ReplaceTestOverrides)
.Build();
ServiceProvider = host.Services;
}
public IServiceProvider ServiceProvider { get; }
private void ReplaceTestOverrides(IServiceCollection services)
{
// services.Replace(new ServiceDescriptor(typeof(ServiceToReplace), testImplementation));
}
private class TestStartup : Startup
{
public override void Configure(IFunctionsHostBuilder builder)
{
SetExecutionContextOptions(builder);
base.Configure(builder);
}
private static void SetExecutionContextOptions(IFunctionsHostBuilder builder)
{
builder.Services.Configure<ExecutionContextOptions>(o => o.AppDirectory = Directory.GetCurrentDirectory());
}
}
}
TestCollection.cs
[CollectionDefinition(Name)]
public class TestCollection : ICollectionFixture<TestHost>
{
public const string Name = nameof(TestCollection);
}
HttpRequestFactory.cs: 创建 Http Post 请求
public static class HttpRequestFactory
{
public static DefaultHttpRequest Create(string method, string contentType, Stream body)
{
var request = new DefaultHttpRequest(new DefaultHttpContext());
var contentTypeWithBoundary = new MediaTypeHeaderValue(contentType)
{
Boundary = $"----------------------------{DateTime.Now.Ticks.ToString("x")}"
};
var boundary = MultipartRequestHelper.GetBoundary(
contentTypeWithBoundary, (int)body.Length);
request.Method = method;
request.Headers.Add("Cache-Control", "no-cache");
request.Headers.Add("Content-Type", contentType);
request.ContentType = $"{contentType}; boundary={boundary}";
request.ContentLength = body.Length;
request.Body = body;
return request;
}
private static string GetBoundary(MediaTypeHeaderValue contentType, int lengthLimit)
{
var boundary = HeaderUtilities.RemoveQuotes(contentType.Boundary);
if (string.IsNullOrWhiteSpace(boundary.Value))
{
throw new InvalidDataException("Missing content-type boundary.");
}
if (boundary.Length > lengthLimit)
{
throw new InvalidDataException(
$"Multipart boundary length limit {lengthLimit} exceeded.");
}
return boundary.Value;
}
}
The MultipartRequestHelper.cs class is available here
最后测试 class:
[Collection(TestCollection.Name)]
public class UploadImagesTests
{
readonly UploadImages UploadImagesFunction;
public UploadImagesTests(TestHost testHost)
{
UploadImagesFunction = new UploadImages(testHost.ServiceProvider.GetRequiredService<IBlobService>());
}
[Theory]
[InlineData("testfile2.jpg")]
public async void HttpTrigger_ShouldReturnListOfUploadedUris(string fileNames)
{
var formFile = GetFormFile(fileNames);
var fileStream = formFile.OpenReadStream();
var request = HttpRequestFactory.Create("POST", "multipart/form-data", fileStream);
var response = (OkObjectResult)await UploadImagesFunction.Run(request);
//fileStream.Close();
Assert.True(response.StatusCode == StatusCodes.Status200OK);
}
private static IFormFile GetFormFile(string fileName)
{
string fileExtension = fileName.Substring(fileName.IndexOf('.') + 1);
string fileNameandPath = GetFilePathWithName(fileName);
IFormFile formFile;
var stream = File.OpenRead(fileNameandPath);
switch (fileExtension)
{
case "jpg":
formFile = new FormFile(stream, 0, stream.Length,
fileName.Substring(0, fileName.IndexOf('.')),
fileName)
{
Headers = new HeaderDictionary(),
ContentType = "image/jpeg"
};
break;
case "png":
formFile = new FormFile(stream, 0, stream.Length,
fileName.Substring(0, fileName.IndexOf('.')),
fileName)
{
Headers = new HeaderDictionary(),
ContentType = "image/png"
};
break;
case "pdf":
formFile = new FormFile(stream, 0, stream.Length,
fileName.Substring(0, fileName.IndexOf('.')),
fileName)
{
Headers = new HeaderDictionary(),
ContentType = "application/pdf"
};
break;
default:
formFile = null;
break;
}
return formFile;
}
private static string GetFilePathWithName(string filename)
{
var outputFolder = Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().Location);
return $"{outputFolder.Substring(0, outputFolder.IndexOf("bin"))}testfiles\{filename}";
}
}
测试似乎命中了函数，req.ContentLength确实有一个值。考虑到这一点，它是否与文件流的管理方式有关？也许方法不对？
如有任何意见，我们将不胜感激。
谢谢
更新 1
根据
“内部流位置意外改变”
在此之后，我再将测试项目中的fileStream位置设置为SeekOrigin.Begin。我开始遇到同样的错误：
“多部分 body 超出长度限制 16384。”
我骑了 50 公里的自行车，睡了个好觉，但我终于想通了:-)。
Azure 函数 (AF) 接受一个名为 'req' 的 HttpRequest 对象作为参数，即
public 异步任务 运行( [HttpTrigger(AuthorizationLevel.Function, "get", "post", Route = "images")] HttpRequest req)
HttpRequest 对象中文件对象的层次结构（连同参数名称）如下：
- HttpRequest -> 请求
- FormCollection -> 表单
- FormFileCollection -> 文件
- FormCollection -> 表单
这是 AF 接受的内容，可以使用 req.Form.Files
访问文件集合在我的测试用例中，我没有 posting 一个 FormCollection 对象，而是试图 post 一个文件流到 Azure 函数。
var formFile = GetFormFile(fileNames);
var fileStream = formFile.OpenReadStream();
var request = HttpRequestFactory.Create("POST", "multipart/form-data", fileStream);
因此，req.Form 有一个无法解释的 Stream 值，req.Form.Files 引发异常。
为了纠正这个问题，我必须执行以下操作：
- 还原作为更新 1 的一部分所做的所有更改。这意味着我从启动文件中删除了 'RequestFormLimits' 设置，并将它们作为函数 运行 方法的属性保留。
- 实例化 FormFileCollection 对象并向其添加 IFormFile
- 使用此 FormFileCollection 作为参数实例化 FormCollection 对象。
- 将 FormCollection 添加到请求对象。
为了实现上述目标，我不得不对代码进行以下更改。
在 HttpRequestFactory
中更改 'Create' 方法 public static DefaultHttpRequest Create(string method, string contentType, FormCollection formCollection)
{
var request = new DefaultHttpRequest(new DefaultHttpContext());
var boundary = $"----------------------------{DateTime.Now.Ticks.ToString("x")}";
request.Method = method;
request.Headers.Add("Cache-Control", "no-cache");
request.Headers.Add("Content-Type", contentType);
request.ContentType = $"{contentType}; boundary={boundary}";
request.Form = formCollection;
return request;
}
添加私有静态 GetFormFiles() 方法
我编写了一个额外的 GetFormFiles() 方法，它调用现有的 GetFormFile() 方法，实例化一个 FormFileCollection 对象并将 IFormFile 添加到它。这个方法又returns一个FormFileCollection.
private static FormFileCollection GetFormFiles(string fileNames)
{
var formFileCollection = new FormFileCollection();
foreach (var file in fileNames.Split(','))
{
formFileCollection.Add(GetFormFile(file));
}
return formFileCollection;
}
更改测试方法
测试方法调用GetFormFiles()获取一个FormFileCollection然后 使用此 FormFileCollection 作为参数实例化 FormCollection 对象，然后将 FormCollection 对象作为参数传递给 HttpRequest 对象，而不是传递 Stream。
[Theory]
[InlineData("testfile2.jpg")]
public async void HttpTrigger_ShouldReturnListOfUploadedUris(string fileNames)
{
var formFiles = GetFormFiles(fileNames);
var formCollection = new FormCollection(null, formFiles);
var request = HttpRequestFactory.Create("POST", "multipart/form-data", formCollection);
var response = (OkObjectResult) await UploadImagesFunction.Run(request);
Assert.True(response.StatusCode == StatusCodes.Status200OK);
}
所以最终问题不在于 'RequestFormLimits'，而在于我在 POST 消息中提交的数据类型。
我希望这个答案能为遇到相同错误消息的人提供不同的视角。
干杯。