c# - Web API请求内容为空

我有一个DelegatingHandler实现来记录请求/响应内容：

public class RequestAndResponseLoggerDelegatingHandler : DelegatingHandler
{
    public IDataAccess Data { get; set; }

    protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        var started = DateTime.UtcNow;
        var response = await base.SendAsync(request, cancellationToken);
        await Log(started, request, response);
        return response;
    }

    private async Task Log(DateTime start, HttpRequestMessage request, HttpResponseMessage response)
    {
        var finished = DateTime.UtcNow;
        var requestContent = await request.Content.ReadAsStringAsync();
        var responseContent = await response.Content.ReadAsStringAsync();
        var info = new ApiLogEntry(start, finished, requestContent, responseContent, request, response);
        Data.Log(info);
    }
}

但是由于某些原因requestContent变成空的。 request.Content.Length确认存在内容，只是未提取内容。

有任何想法吗？

最佳答案

读取请求主体流并将其绑定到参数中，作为绑定的结果，该流已定位到末尾。这就是为什么它空无一物。如果您要查找request.Content.ReadAsStringAsync()之前的开头，它应该可以工作。取而代之的是，您可以在绑定发生之前先简单地读取请求正文，诸如此类。

public class RequestAndResponseLoggerDelegatingHandler : DelegatingHandler
{
    public IDataAccess Data { get; set; }

    protected override async Task<HttpResponseMessage> SendAsync(
                            HttpRequestMessage request,
                                 CancellationToken cancellationToken)
    {
        var started = DateTime.UtcNow;
        var requestContent = await request.Content.ReadAsStringAsync();

        var response = await base.SendAsync(request, cancellationToken);

        var responseContent = await response.Content.ReadAsStringAsync();
        await Log(started, request, response, requestContent, responseContent);
        return response;
    }

    private async Task Log(DateTime start, HttpRequestMessage request,
                             HttpResponseMessage response, string requestContent,
                                string responseContent)
    {
        var finished = DateTime.UtcNow;
        var info = new ApiLogEntry(start, finished, requestContent, responseContent,
                                        request, response);
        Data.Log(info);
    }
}