为什么ResponseMessage.Content在等待PostAsJsonAsync请求后一直为空？

Question

我们正在向ResponseMessage.Content中持续返回[]的API发布“maintenanceEvent”。如果我在这里写的代码有问题，我需要一些专家指导。

private async Task SendMaintenanceEvent(object maintenanceEvent, MaintenanceEventType maintenanceEventType) 
{ 
    string endpointAddress = "TheEndpointURI"; 
    string credentials = "OurCredentials"; 
    string credentialsBase64 = Convert.ToBase64String(System.Text.ASCIIEncoding.ASCII.GetBytes(credentials)); 

    // Convert the maintenanceEvent object to consumable JSON, then encode it to a StringContent object. 
    this.responseInfo.MaintenanceEventAsJSON = System.Web.Helpers.Json.Encode(maintenanceEvent); 
    StringContent stringContent = new StringContent(this.responseInfo.MaintenanceEventAsJSON, Encoding.UTF8, "application/json"); 
    using (HttpClient httpClient = new HttpClient()) 
    { 
     httpClient.BaseAddress = new Uri(endpointAddress); 
     httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", credentialsBase64); 
     this.responseInfo.AuthorizationHeader = httpClient.DefaultRequestHeaders.Authorization.ToString(); 
     this.responseInfo.EndpointUri = httpClient.BaseAddress.AbsoluteUri; 

     // The async post. 
     this.responseInfo.ResponseMessage = await httpClient.PostAsJsonAsync(access.EndpointDirectory, stringContent).ConfigureAwait(false); 

     this.responseInfo.ResponseStatusCode = (int)this.responseInfo.ResponseMessage.StatusCode; 

     // Consistently returns true so long as my credentials are valid. 
     // When the auth credentials are invalid, this returns false. 
     if (this.responseInfo.ResponseMessage.IsSuccessStatusCode) 
     { 
      // I expect to see some data from the service. 
      this.responseInfo.ResponseContent = this.responseInfo.ResponseMessage.Content.ReadAsStringAsync(); 
     } 
    } 
} 

Try/Catch块和一些公司特定的信息被省略。上面的responseInfo对象只是一个有一些属性的模型来从这个方法中收集信息，所以我们可以记录事件。

我怀疑问题可能出在PostAsJsonAsync命令下面的代码中。但我不知道该怎么做。谢谢你的帮助。

Answer 1

这（略作调整）是你想做的事（根据需要替换为自己的变量）什么：

using (HttpClient httpClient = new HttpClient()) 
{ 
    // ... 
    HttpResponseMessage responseMessage = await httpClient.PostAsJsonAsync(access.EndpointDirectory, stringContent).ConfigureAwait(false); 
    // ... 
    string responseBody = await responseMessage.Content.ReadAsStringAsync().ConfigureAwait(false); 
    // ... 
} 

即您必须等待ReadAsStringAsync()才能获取实际内容。

为了完整，请注意HttpResponseMessage和HttpResponseMessage.Content是IDisposable。