Question

我有以下函数Handle_Log_Clicked()调用异步任务CreateLogCall，它使用repository.CREATE()方法发出HTTP POST请求，并返回HttpResponseMessage类型作为返回值：

我必须使用Handle_Log_Clicked()方法中的响应从我从CreateLogCall ()获得的HttpResponseMessage响应中检索Headers。

在下面的代码中，响应未在HttpResponseMessage response中设置。

当我试图获取响应的子字符串时会导致错误。

async void Handle_Log_Clicked(object sender, System.EventArgs e)
    {
        try
        {
            HttpResponseMessage response = await CreateLogCall();
            Debug.WriteLine("Response: ", response);
            var resultHeader = response.Headers.Location.ToString();
            string relatedCallID = resultHeader.Substring(resultHeader.IndexOf('('), resultHeader.Length -1 );

            await CreateLogCallProducts(relatedCallID);

            if (!response.IsSuccessStatusCode)
                await DisplayAlert("Failure", "The data could not be saved", "Ok");
            else
                await DisplayAlert("Success", "The call is logged successfully", "Ok");
        }
        catch (Exception err)
        {
            await DisplayAlert("Error", "Please fill all the details", "Ok");
            Debug.WriteLine(err.Message);
        }
    }

public async Task<HttpResponseMessage> CreateLogCall()
    {
        HttpResponseMessage result = null;
        try
        {
            if (isPrescriber)
            {
                Debug.WriteLine("inside prescriber calls");
                result = await repository.Create(GlobalVariables.AuthToken, "xxxx", logCall);
            }
            else
            {

                result = await repository.Create(GlobalVariables.AuthToken, "yyyyy", logCall);
            }

            return result;
        }
        catch (Exception e)
        {
            Debug.WriteLine(e.Message);
        }
        return result;
    }

Inside repository.cs

public async Task<HttpResponseMessage> Create(string accessToken, string entity, JObject data)
    {
            // The URL for the OData organization web service.
            string url = GlobalVariables.RootUrl + GlobalVariables.EndPoint + entity;

            var content = new StringContent(data.ToString(), Encoding.UTF8, "application/json");
            // Build and send the HTTP request.
            HttpClient httpClient = new HttpClient();
            httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", accessToken);

            // Wait for the web service response.
            HttpResponseMessage response;
            response = await httpClient.PostAsync(url, content);
            Debug.WriteLine(response);
            return response;
    }

放入调试器时，我可以看到响应值传递给Handle_Log_Clicked（），但是当代码到达substring方法时，它会抛出错误：

索引和长度必须指向字符串中的位置。参数名称：长度

代码：Debug.WriteLine("Response: ", response);不会打印响应，但调试器会在其中显示值。

C＃Async Task返回值但无法访问值进行操作

0 个答案: