将 XML 发布到 asp.net core 2.0 web api

Question

我正在尝试将 XML 发布到 asp.net core 2：

$.ajax({
    type: "POST",
    url: 'api/Test',
    data: "<test>hello<test>",
    contentType: "application/xml",
    success: function (response) { alert(response); },
});

我应该如何编写动作，让它接受 xml 作为参数？

• IActionResult Post([FromBody]string xml) -> xml 为空
• IActionResult Post([FromBody]XElement xml) -> xml 为空
• IActionResult Post(XElement xml) -> InvalidOperationException：无法创建“System.Xml.Linq.XElement”类型的实例。模型绑定的复杂类型不能是抽象类型或值类型，并且必须具有无参数构造函数。
• IActionResult Post(string xml) -> xml 为空

在 Startup.ConfigureServices 中：

services.AddMvc()
    .AddXmlSerializerFormatters();

如何编写控制器以使其接受 XML 作为参数？我知道我可以从 HttpContext.Request 中读取它，但我希望它是参数

Answer 1

这些解决方案有效，但在 .NET Core 3 中有一个缺点 - 它们会导致异常（在调用 XDocument.LoadAsync 内部）：

System.InvalidOperationException：不允许同步操作。改为调用 ReadAsync 或将 AllowSynchronousIO 设置为 true。

这是我使用 FileBufferingReadStream 修改后的解决方案（灵感来自 Microsoft.AspNetCore.Mvc.Formatters.XmlSerializerInputFormatter 的代码）

public override async Task<InputFormatterResult> ReadRequestBodyAsync(InputFormatterContext context)
{
    Check.NotNull(context, nameof(context));

    var xmlDoc = await LoadXmlFromRequestAsync(context.HttpContext);
    return InputFormatterResult.Success(xmlDoc);
}

private static async Task<XDocument> LoadXmlFromRequestAsync(HttpContext httpContext)
{
    Check.NotNull(httpContext, nameof(httpContext));

    //Code from Microsoft.AspNetCore.Mvc.Formatters.XmlSerializerInputFormatter to use FileBufferingReadStream to avoid synchronous read issue:
    //https://github.com/dotnet/aspnetcore/issues/18723 - Synchronous call inside XDocument.LoadAsync causes --> System.InvalidOperationException: Synchronous operations are disallowed. Call ReadAsync or set AllowSynchronousIO to true instead.
    int memoryThreshold = 30720;
    long contentLength = httpContext.Request.ContentLength.GetValueOrDefault();
    if (contentLength > 0 && contentLength < memoryThreshold)
    {
        memoryThreshold = (int)contentLength;
    }

    var readStream = new FileBufferingReadStream(httpContext.Request.Body, memoryThreshold);
    httpContext.Response.RegisterForDispose(readStream);
    await readStream.DrainAsync(CancellationToken.None);
    readStream.Seek(0, SeekOrigin.Begin);

    try
    {
        using (var streamReader = new StreamReader(readStream))
        {
            var xmlDoc = await XDocument.LoadAsync(streamReader, LoadOptions.None, CancellationToken.None);
            return xmlDoc;
        }
    }
    finally
    {
        await readStream.DisposeAsync();
    }
}

Answer 2

只是对Liero给出的答案进行了更改，您应该使用StreamReader，这样您就可以支持多种编码。使用 UTF-8、UTF-16 和 ASCI 声明标头测试了我的解决方案。

从 XDocumentInputFormatter 更改方法：

public override async Task<InputFormatterResult> ReadRequestBodyAsync(InputFormatterContext context)
{
    var xmlDoc = await XDocument.LoadAsync(context.HttpContext.Request.Body, LoadOptions.None, CancellationToken.None);
    return InputFormatterResult.Success(xmlDoc);
}

到下面

public override async Task<InputFormatterResult> ReadRequestBodyAsync(InputFormatterContext context) {
        // Use StreamReader to convert any encoding to UTF-16 (default C# and sql Server).
        using (var streamReader = new StreamReader(context.HttpContext.Request.Body)) {
            var xmlDoc = await XDocument.LoadAsync(streamReader, LoadOptions.None, CancellationToken.None);
            return InputFormatterResult.Success(xmlDoc);
        }
    }

Answer 3

我最终创建了自定义 InputFormatter，这非常简单，但如果有更好的选择，非常欢迎您写一个答案！

public class XDocumentInputFormatter : InputFormatter, IInputFormatter, IApiRequestFormatMetadataProvider
{
    public XDocumentInputFormatter()
    {
        SupportedMediaTypes.Add("application/xml");
    }

    protected override bool CanReadType(Type type)
    {
        if (type.IsAssignableFrom(typeof(XDocument))) return true;
        return base.CanReadType(type);
    }

    public override async Task<InputFormatterResult> ReadRequestBodyAsync(InputFormatterContext context)
    {
        var xmlDoc = await XDocument.LoadAsync(context.HttpContext.Request.Body, LoadOptions.None, CancellationToken.None);
        return InputFormatterResult.Success(xmlDoc);
    }
}

在startup.cs中注册XDocumentInputFormatter

public void ConfigureServices(IServiceCollection services)
{
    services.AddMvc(options => options.InputFormatters.Insert(0, new XDocumentInputFormatter()));
}