重构一个异步方法

Question

我有一个项目，其中有一个动作目录。在每个动作的核心中，可能会有一个或多个网络调用。因此，核心方法看起来像以下内容：

public async Task<Result> evaluate(){
//some setup chunk
        try
        {
            responsefromUri = await requestManager.Post(resourceUri, "");
        }
            // The non-retryable exception will directly trickle up.
        catch (RetryableException exception)
        {
            return BuildFailedCheckResult(
                StatusCode.Abandoned,
                Check1 + " abandoned. Failed to read the response for resource: " + resourceUri + " with exception: " + exception.Message);
        }

        if (string.IsNullOrEmpty(responsefromUri))
        {
            return BuildFailedCheckResult(
                StatusCode.Failed,
                Check1 + " failed. Empty response for resource: " + resourceUri);
        }

        try
        {
            responseJson = JObject.Parse(responsefromUri);
        }
        catch (JsonReaderException e)
        {
            throw new InvalidOperationException(Check1 + " check failed parsing resource: " + resourceUri, e);
        }
// use responseJson to get data and process further
}

对于每个网络调用，都有这个块。我希望将其提取出来。现在，我无法这样做，因为存在一个await，如果要提取它，我需要一个异步方法；但是要返回失败的检查结果，我需要一个out变量，而在异步方法中不允许使用。重构此代码的正确方法是什么？当存在多个网络调用时，该方法会变得非常冗长。

- dknight

Answer 1

只需将您的“进一步处理”打包到一个Func中，例如：

public async Task<Result> evaluate(Uri resourceUri, Func<JObject, Result> action)
{
    string responsefromUri;

    try
    {
        responsefromUri = await requestManager.Post(resourceUri, "");
    }
        // The non-retryable exception will directly trickle up.
    catch (RetryableException exception)
    {
        return BuildFailedCheckResult(
            StatusCode.Abandoned,
            Check1 + " abandoned. Failed to read the response for resource: " + resourceUri + " with exception: " + exception.Message);
    }

    if (string.IsNullOrEmpty(responsefromUri))
    {
        return BuildFailedCheckResult(
            StatusCode.Failed,
            Check1 + " failed. Empty response for resource: " + resourceUri);
    }

    JObject responseJson;
    try
    {
        responseJson = JObject.Parse(responsefromUri);
    }
    catch (JsonReaderException e)
    {
        throw new InvalidOperationException(Check1 + " check failed parsing resource: " + resourceUri, e);
    }

    return action(responseJson);
}

使用示例：

// Example Usage
public Task<Result> DoStuff() 
{
    Uri uri = new Uri("http://localhost");

    return evaluate(uri, jobject => {
        return new Result(jobject["result"]);
    });
}

- jamespconnor

Answer 2

你可以将代码块重构为一个单独的私有方法，返回一个Task，并添加一个JsonResult类，其中包含“happy-path”结果。

- David Guida