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,response);
        Data.Log(info);
    }
}

但由于某种原因,requestContent即将出现. request.Content.Length确认有内容,它只是没有被提取.

有任何想法吗？

解决方法

读取请求主体流并将其绑定到参数中,并且作为绑定的结果,流已经定位到最后.这就是它变得空洞的原因.如果你在request.Content.ReadAsstringAsync()之前寻找开头,它应该工作.而不是那样,你可以在绑定发生之前先简单地读取请求体,有些事情是这样的.

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,response,responseContent);
        return response;
    }

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