从单个方法C＃Web API返回不同的类型

Question

我有一个Web API，调用时会返回一个客户对象。 但是，如果发生错误，我想返回一个错误字符串。 但是，如何在单个C＃方法中返回不同的类型。

 public IEnumerable<Customers> getCustomersById(string id){

        var isAuthenticated = tokenAuthorization.validateToken(access_token);
        if (isAuthenticated)
        {
            List<Customers> customers = new List<Customers>();
            Customers customer = null;
            customer = new Customers();
            customer.kunnr = id;
            customer.name = "John Doe";
            customers.Add(customer);
            return customers;
        }
        else
        {
            return 'Not a valid Access Token';
        }

 }

Answer 1

如果您发布的代码位于API控制器中，则可以执行以下操作：

public IHttpActionResult getCustomersById(string id){

    var isAuthenticated = tokenAuthorization.validateToken(access_token);
    if (isAuthenticated)
    {
        List<Customers> customers = new List<Customers>();
        Customers customer = null;
        customer = new Customers();
        customer.kunnr = id;
        customer.name = "John Doe";
        customers.Add(customer);
        return Ok(customers);
    }
    else
    {
        return BadRequest("Not a valid Access Token");
    }
}

如果您的代码在服务中，则可以在控制器中执行相同的操作，但是会从服务中引发自定义异常，如下所示：

public IEnumerable<Customers> getCustomersById(string id){

    var isAuthenticated = tokenAuthorization.validateToken(access_token);
    if (isAuthenticated)
    {
        List<Customers> customers = new List<Customers>();
        Customers customer = null;
        customer = new Customers();
        customer.kunnr = id;
        customer.name = "John Doe";
        customers.Add(customer);
        return customers;
    }
    else
    {
        throw new TokenInvalidException("Not a valid Access Token");
    }
}

然后，在控制器中，您可以在该API调用中捕获该错误，并使用与上一示例所示相同的返回类型和方法。 或者通用错误处理程序也可以处理该错误。 尽管我建议您在使用自定义错误时实现自己的错误处理程序过滤器，这样您就不会返回500个错误。

Answer 2

不返回，而是抛出。

throw new HttpResponseException(HttpStatusCode.Unauthorized);

Answer 3

好吧，由于您的第二条消息是“字符串”，是由于异常所致，因此应按以下方式处理：

public IEnumerable<Customers> getCustomersById(string id){

        var isAuthenticated = tokenAuthorization.validateToken(access_token);
        if (isAuthenticated)
        {
            List<Customers> customers = new List<Customers>();
            Customers customer = null;
            customer = new Customers();
            customer.kunnr = id;
            customer.name = "John Doe";
            customers.Add(customer);
            return customers;
        }else
        {
        var resp = new HttpResponseMessage(HttpStatusCode.NotFound)
        {
            Content = new StringContent(string.Format("No person with ID = {0}", id)),
            ReasonPhrase = "Person ID Not Found"
        }
        throw new HttpResponseException(resp);
    }
    return item;
}

如您所见，上面的示例可以将某些级别的信息作为异常的一部分传递给客户端，以进行正确的处理。

Answer 4

您可以创建一些通用的api响应模型，例如

public class ApiResponse<T>{
public T Data {get;set;} // it will contains the response
public string Message {get;set;} // here you can put you error message
public boolean IsSuccess {get;set;} //this will be true only when no error
}

比你的回应

public ApiResponse<IEnumerable<Customers>> getCustomersById(string id){
var retVal = new ApiResponse<IEnumerable<Customers>>();
var isAuthenticated = tokenAuthorization.validateToken(access_token);
if(!isAuthenticated){
retVal.Message="You are not authrized";
return retVal;
}
try{
var data = yourList;
retVal.IsSuccess = true;
retVal.Data = yourList;
}
catch(exception ex){
retVal.Message=yourmessage;
}
return retVal;
}

Answer 5

我更喜欢通用解决方案。

public class ResponseList<T> {

        public ResponseList() {
            Exceptions = new Dictionary<string, string>();
        }

        public ResposeCodes ResposeCode { get; set; } = ResposeCodes.Success;

        public Dictionary<string, string> Exceptions { get; set; } = null;

        public List<T> DataList { get; set; } = null;

        public string ResponseMessage { get; set; } = null;
    }

此处的响应代码应如下所示：

public enum ResposeCodes
    {
        Error = 1,
        Success = 2,
        NoDataFound = 3
    }

您可以提供“您的数据已成功保存”之类的响应消息。

这是如何使用它的好例子

public ResponseList<Model> GetData( string ta_id ) {
            ResponseList<Model> response = new ResponseList<Model>();
            List<Model> res = null;
            try
            {
                res = new List<Model>();
                //perform your operations
                res.data = responselist;
            }
            catch (Exception ex)
            {
                HandleResponse.AddException(ex, ref response);
            }
            response.DataList = res;
            return response;
        }

这是句柄响应类

public static class HandleResponse {
        public static void AddException<T>( Exception ex, ref ResponseList<T> response) {
            response.ResposeCode = ResposeCodes.Error;
            response.Exceptions.Add(ResposeCodes.Error.ToString(), ex.Message);


            //inserting errors into table                

        }

        public static void AddErrorMessage<T>( string message, ref ResponseList<T> r ) {
            r.ResposeCode = ResposeCodes.Error;
            r.ResponseMessage = message;
        }

        public static void AddSuccessMessage<T>( string message, ref ResponseList<T> r ) {
            r.ResposeCode = ResposeCodes.Success;
            r.ResponseMessage = message;
        }
    }

所有api中都应遵循此规则。 我们正在webapi中使用此通用解决方案。 到现在为止，一切都很好。