我应该如何在 Windows Phone 7 上使用 RestSharp 实现 ExecuteAsync？

Question

我正在尝试使用 RestSharp GitHub wiki 上的文档来实现对我的 REST API 服务的调用，但我遇到了特别是 ExecuteAsync 方法的问题。

目前我的 API 类代码如下所示：

public class HarooApi
{
    const string BaseUrl = "https://domain.here";

    readonly string _accountSid;
    readonly string _secretKey;

    public HarooApi(string accountSid, string secretKey)
    {
        _accountSid = accountSid;
        _secretKey = secretKey;
    }

    public T Execute<T>(RestRequest request) where T : new()
    {
        var client = new RestClient();
        client.BaseUrl = BaseUrl;
        client.Authenticator = new HttpBasicAuthenticator(_accountSid, _secretKey);
        request.AddParameter("AccountSid", _accountSid, ParameterType.UrlSegment);
        client.ExecuteAsync<T>(request, (response) =>
        {
            return response.Data;
        });
    }
}

我知道这与 GitHub 页面上的内容略有不同，但我将它与 WP7 一起使用，并相信该示例适用于 C#，因此使用了 ExecuteAsync 方法。

我的问题是 ExecuteAsync 命令应该包含什么。我不能使用return response.Data，因为我被警告了：

'System.Action<RestSharp.RestResponse<T>,RestSharp.RestRequestAsyncHandle>' returns void, a return keyword must not be followed by an object expression

有没有人对如何解决这个问题有任何见解或可能有帮助的教程？

Answer 1

老问题，但如果您使用 C# 5，则可以通过创建返回 T 任务的 TaskCompleteSource 来获得通用执行类。您的代码可能如下所示：

public Task<T> ExecuteAsync<T>(RestRequest request) where T : new()
    {
        var client = new RestClient();
        var taskCompletionSource = new TaskCompletionSource<T>();
        client.BaseUrl = BaseUrl;
        client.Authenticator = new HttpBasicAuthenticator(_accountSid, _secretKey);
        request.AddParameter("AccountSid", _accountSid, ParameterType.UrlSegment);
        client.ExecuteAsync<T>(request, (response) => taskCompletionSource.SetResult(response.Data));
        return taskCompletionSource.Task;
    }

并像这样使用它：

private async Task DoWork()
    {
        var api = new HarooApi("MyAcoountId", "MySecret");
        var request = new RestRequest();
        var myClass = await api.ExecuteAsync<MyClass>(request);

        // Do something with myClass
    }

Answer 2

您的代码应如下所示：

public class HarooApi
{
    const string BaseUrl = "https://domain.here";

    readonly string _accountSid;
    readonly string _secretKey;

    public HarooApi(string accountSid, string secretKey)
    {
        _accountSid = accountSid;
        _secretKey = secretKey;
    }

    public void ExecuteAndGetContent(RestRequest request, Action<string> callback)
    {
        var client = new RestClient();
        client.BaseUrl = BaseUrl;
        client.Authenticator = new HttpBasicAuthenticator(_accountSid, _secretKey);
        request.AddParameter("AccountSid", _accountSid, ParameterType.UrlSegment);
        client.ExecuteAsync(request, response =>
        {
            callback(response.Content);
        });
    }

    public void ExecuteAndGetMyClass(RestRequest request, Action<MyClass> callback)
    {
        var client = new RestClient();
        client.BaseUrl = BaseUrl;
        client.Authenticator = new HttpBasicAuthenticator(_accountSid, _secretKey);
        request.AddParameter("AccountSid", _accountSid, ParameterType.UrlSegment);
        client.ExecuteAsync<MyClass>(request, (response) =>
        {
            callback(response.Data);
        });
    }
}

我添加了两个方法，所以你可以检查你想要的（来自响应正文的字符串内容，或者这里由MyClass表示的反序列化类）

Answer 3

作为fine answer 的替代（或补充）Gusten。您可以使用ExecuteAsync。这样您就不必手动处理TaskCompletionSource。注意签名中的async 关键字。

更新： 截至106.4.0 ExecuteTaskAsync 已过时。由于104.2，您应该改用ExecuteAsync：

public async Task<T> ExecuteAsync<T>(RestRequest request) where T : new()
{
    var client = new RestClient();
    client.BaseUrl = BaseUrl;
    client.Authenticator = new HttpBasicAuthenticator(_accountSid, _secretKey);
    request.AddParameter("AccountSid", _accountSid, ParameterType.UrlSegment);
    IRestResponse<T> response = await client.ExecuteAsync<T>(request);
    return response.Data;
}

旧答案：

public async Task<T> ExecuteAsync<T>(RestRequest request) where T : new()
{
    var client = new RestClient();
    client.BaseUrl = BaseUrl;
    client.Authenticator = new HttpBasicAuthenticator(_accountSid, _secretKey);
    request.AddParameter("AccountSid", _accountSid, ParameterType.UrlSegment);
    IRestResponse<T> response = await client.ExecuteTaskAsync<T>(request); // Now obsolete
    return response.Data;
}

Answer 4

或者更准确地说是这样的：

    public async Task<IRestResponse<T>> ExecuteAsync<T>(IRestRequest request) where T : class, new()
    {
        var client = new RestClient(_settingsViewModel.BaseUrl);

        var taskCompletionSource = new TaskCompletionSource<IRestResponse<T>>();
        client.ExecuteAsync<T>(request, restResponse =>
        {
            if (restResponse.ErrorException != null)
            {
                const string message = "Error retrieving response.";
                throw new ApplicationException(message, restResponse.ErrorException);
            }
            taskCompletionSource.SetResult(restResponse);
        });

        return await taskCompletionSource.Task;
    }

Answer 5

下面的工作完成了

public async Task<IRestResponse<T>> ExecuteAsync<T>(IRestRequest request) where T : class, new()
{
    var client = new RestClient
    {
        BaseUrl = _baseUrl,
        Authenticator = new HttpBasicAuthenticator(_useraname, _password),
        Timeout = 3000,
    };

    var tcs = new TaskCompletionSource<T>();
    client.ExecuteAsync<T>(request, restResponse =>
    {
        if (restResponse.ErrorException != null)
        {
            const string message = "Error retrieving response.";
            throw new ApplicationException(message, restResponse.ErrorException);
        }
        tcs.SetResult(restResponse.Data);
    });

    return await tcs.Task as IRestResponse<T>;

}

Answer 6

由于public static RestRequestAsyncHandle ExecuteAsync(this IRestClient client, IRestRequest request, Action<IRestResponse> callback) 已被弃用，您应该改用public Task<IRestResponse> ExecuteAsync(IRestRequest request, CancellationToken token = default)。

以下代码

client.ExecuteAsync(request, response => { callback(response.Content); });

应该改为

await client.ExecuteAsync(request).ContinueWith(task => callback(task.Result.Content));