使用 HttpClient 通过 GET 连接到 WebApi 时出现 404 错误

Question

我在尝试使用 HttpClient 通过 GET 连接到 WebApi 服务时遇到 404 错误。但是，POST 工作没有任何问题。在下面的代码中，我有一个始终使用的 CreditCard 类。

这是我的路由配置：

config.Routes.MapHttpRoute(
    name: "DefaultApi",
    routeTemplate: "api/{controller}/{id}",
    defaults: new { id = RouteParameter.Optional }
);

这是我调用异步操作的代码：

Task task1 = RegisterCard(card, false);
Task task2 = FetchCard(cardid, false);

这是我的包含异步操作的代码：

private async Task RegisterCard(CreditCard card, bool runAsync)
{
    try
    {
        using (HttpClient client = new HttpClient())
        {
            client.BaseAddress = new Uri("http://localhost:63801/");
            client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

            HttpResponseMessage response = runAsync
                                            ? await client.PostAsJsonAsync("api/card", card)
                                            : client.PostAsJsonAsync("api/card", card).Result;

            response.EnsureSuccessStatusCode();
        }
    }
    catch (HttpRequestException ex)
    {
        throw new HttpRequestException(ex.Message, ex.InnerException);
    }
}

private async Task FetchCard(int cardid, bool runAsync)
{
    CreditCard card = new CreditCard();

    try
    {
        using (HttpClient client = new HttpClient())
        {
            client.BaseAddress = new Uri("http://localhost:63801/");
            client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

            HttpResponseMessage response = runAsync
                                            ? await client.GetAsync("api/card/" + cardid)
                                            : client.GetAsync("api/card/" + cardid).Result;

            response.EnsureSuccessStatusCode();
            }
        }
    }
    catch (HttpRequestException ex)
    {
        throw new HttpRequestException(ex.Message, ex.InnerException);
    }
}

这是我的 apiController 代码：

[HttpPost]
public HttpResponseMessage Register(CreditCard card)
{
    HttpResponseMessage result;

    try
    {
        RegisterResponse response = _cardRepository.Register(card);

        result = Request.CreateResponse(HttpStatusCode.Created, response);
    }
    catch (Exception ex)
    {
        // TODO: add logging
        result = Request.CreateErrorResponse(HttpStatusCode.BadRequest, "failed to register card");
    }
    finally
    {
        // TODO: add audit logging of what attempted and who attempted it
    }

    return result;
}

[HttpGet]
public CreditCard Fetch(int cardid)
{
    CreditCard card = new CreditCard();

    try
    {
        card = _cardRepository.Fetch(cardid);
    }
    catch (Exception ex)
    {
        // TODO: add logging
    }
    finally
    {
        // TODO: add audit logging of what attempted and who attempted it
    }

    return card;
}

还有我的 CardRepository 代码：

public RegisterResponse Register(Models.CreditCard card)
{
    using (CreditCardContext ccContext = new CreditCardContext())
    {
        card.MaskedNumber = "XXXXXXXXXXXX" + card.Number.Substring(card.Number.Length - 4, 4);
        card.Number = Crypto.EncryptData_Aes(card.Number, KeyType.CardNumberKey);
        card.CardGuid = Guid.NewGuid().ToString();
        ccContext.CreditCards.Add(card);
        ccContext.SaveChanges();
    }
    card.ResetSensitive();

    RegisterResponse response = new RegisterResponse
    {
        IsSuccess = true,
        Message = "successfully registered card",
        CreditCard = card
    };

    return response;
}

public CreditCard Fetch(int cardid) // , bool masked
{
    CreditCard card;

    using (CreditCardContext ccContext = new CreditCardContext())
    {
        card = ccContext.CreditCards.SingleOrDefault(x => x.Card_ID == cardid);
    }

    return card;
}

问题：为什么我在使用 HttpClient 对象通过 HttpGet 连接到我的 WebApi 服务时收到 404 错误，但是当我使用 HttpPost 时，它可以正常工作？

Answer 1

问题在于您的Fetch 方法中的参数命名。

如果您按照指定的路线将其更改为id，它应该可以工作：

[HttpGet]
public CreditCard Fetch(int id) // , bool masked
{
   ...
}

或者，您也可以使用命名参数调用 api（例如 api/card/?cardid=2）

Answer 2

在 Web API 2 中，您可以使用 Attribute Routing

[Route("api/card/{cardid:int}")]
[HttpGet]
public CreditCard Fetch(int cardid)
{
    ...
}