我试图返回一个状态代码304未修改的web api控制器中的GET方法。

我成功的唯一方法是这样的:

public class TryController : ApiController
{
    public User GetUser(int userId, DateTime lastModifiedAtClient)
    {
        var user = new DataEntities().Users.First(p => p.Id == userId);
        if (user.LastModified <= lastModifiedAtClient)
        {
             throw new HttpResponseException(HttpStatusCode.NotModified);
        }
        return user;
    }
}

这里的问题是,它不是一个异常,它只是没有修改,所以客户端缓存是OK的。 我还希望返回类型是一个用户(所有的web api示例显示与GET)不返回HttpResponseMessage或类似的东西。


当前回答

如果你需要返回一个IHttpActionResult并且想要返回错误代码和消息,使用:

return ResponseMessage(Request.CreateErrorResponse(HttpStatusCode.NotModified, "Error message here"));

其他回答

如果你需要返回一个IHttpActionResult并且想要返回错误代码和消息,使用:

return ResponseMessage(Request.CreateErrorResponse(HttpStatusCode.NotModified, "Error message here"));

在MVC 5中,事情变得更简单了:

return new StatusCodeResult(HttpStatusCode.NotModified, this);
public HttpResponseMessage Post(Article article)
{
    HttpResponseMessage response = Request.CreateResponse<Article>(HttpStatusCode.Created, article);

    string uriToTheCreatedItem = Url.Route(null, new { id = article.Id });
    response.Headers.Location = new Uri(Request.RequestUri, uriToTheCreatedItem);

    return response;
}

使用Web API 2中引入的更现代的IHttpActionResult对@Aliostads进行了更新。

https://learn.microsoft.com/en-us/aspnet/web-api/overview/getting-started-with-aspnet-web-api/action-results#ihttpactionresult

public class TryController : ApiController
{
    public IHttpActionResult GetUser(int userId, DateTime lastModifiedAtClient)
    {
        var user = new DataEntities().Users.First(p => p.Id == userId);
        if (user.LastModified <= lastModifiedAtClient)
        {
            return StatusCode(HttpStatusCode.NotModified);
            // If you would like to return a Http Status code with any object instead:
            // return Content(HttpStatusCode.InternalServerError, "My Message");
        }
        return Ok(user);
    }
}

我不知道答案所以问ASP。NET团队。

因此,诀窍是将签名更改为HttpResponseMessage并使用Request.CreateResponse。

[ResponseType(typeof(User))]
public HttpResponseMessage GetUser(HttpRequestMessage request, int userId, DateTime lastModifiedAtClient)
{
    var user = new DataEntities().Users.First(p => p.Id == userId);
    if (user.LastModified <= lastModifiedAtClient)
    {
         return new HttpResponseMessage(HttpStatusCode.NotModified);
    }
    return request.CreateResponse(HttpStatusCode.OK, user);
}