[ApiController]
[Route("[controller]")]
public class WeatherForecastController : ControllerBase
{private static readonly string[] Summaries = new[]{"Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"};private readonly ILogger<WeatherForecastController> _logger;public WeatherForecastController(ILogger<WeatherForecastController> logger){_logger = logger;}[HttpGet]public IEnumerable<WeatherForecast> Get(){var rng = new Random();return Enumerable.Range(1, 5).Select(index => new WeatherForecast{Date = DateTime.Now.AddDays(index),TemperatureC = rng.Next(-20, 55),Summary = Summaries[rng.Next(Summaries.Length)]}).ToArray();}
}

运行应用程序时，将以JSON格式显示以下输出：

[{"date": "2019-09-16T13:08:39.5994786-05:00","temperatureC": -8,"temperatureF": 18,"summary": "Bracing"},{"date": "2019-09-17T13:08:39.5995153-05:00","temperatureC": 54,"temperatureF": 129,"summary": "Cool"},{"date": "2019-09-18T13:08:39.5995162-05:00","temperatureC": 33,"temperatureF": 91,"summary": "Bracing"},{"date": "2019-09-19T13:08:39.5995166-05:00","temperatureC": 38,"temperatureF": 100,"summary": "Balmy"},{"date": "2019-09-20T13:08:39.599517-05:00","temperatureC": -3,"temperatureF": 27,"summary": "Sweltering"}
]

太好了，其API的工作与我们期望的一样，只是它没有给我们带来有意义的回应。我们知道数据是响应中非常重要的部分，但是，随便吐出数据是因为JSON响应实际上并没有太大帮助，尤其是当每个请求之间发生意外行为时。

//This is just an idiot example to trigger an error
int num = Convert.ToInt32("a");

上面的代码尝试将包含非数字值的string转换为integer类型，这将在运行时导致错误。响应输出看起来像这样：

using AutoWrapper;

3.在UseRouting()中间件“之前”的Startup.cs的Configure()方法中注册下面的中间件：

app.UseApiResponseAndExceptionWrapper();

默认的API版本格式设置为“ 1.0.0.0”。如果希望为API指定其他版本格式，则可以执行以下操作：

app.UseApiResponseAndExceptionWrapper(new ApiResponseOptions { ApiVersion = "2.0" });

很简单！现在，尝试再次构建并运行ASP.NET Core API默认应用程序。根据我们的示例，以下是“WeatherForecastController” API 响应的样子：

{"message": "Request successful.","isError": false,"result": [{"date": "2019-09-16T23:37:51.5544349-05:00","temperatureC": 21,"temperatureF": 69,"summary": "Mild"},{"date": "2019-09-17T23:37:51.554466-05:00","temperatureC": 28,"temperatureF": 82,"summary": "Cool"},{"date": "2019-09-18T23:37:51.554467-05:00","temperatureC": 21,"temperatureF": 69,"summary": "Sweltering"},{"date": "2019-09-19T23:37:51.5544676-05:00","temperatureC": 53,"temperatureF": 127,"summary": "Chilly"},{"date": "2019-09-20T23:37:51.5544681-05:00","temperatureC": 22,"temperatureF": 71,"summary": "Bracing"}]
}

如果您注意到了，那么输出现在在响应中包含一些属性，例如message，isError以及在result属性中包含的实际数据。

{"isError": true,"responseException": {"exceptionMessage": "Request not found. The specified uri does not exist.","details": null,"referenceErrorCode": null,"referenceDocumentLink": null,"validationErrors": null}
}

现在注意到响应对象是如何更改的。statusCode自动设置为404。当已经发生任何意外错误或异常时，result属性将自动省略，而显示responseException属性以显示错误消息和额外信息。

//This is just an idiot example to trigger an error
int num = Convert.ToInt32("a");

现在它将给您以下响应：

{"isError": true,"responseException": {"exceptionMessage": "Unhandled Exception occured. Unable to process the request.","details": null,"referenceErrorCode": null,"referenceDocumentLink": null,"validationErrors": null}
}

控制台窗口将显示以下内容：

app.UseApiResponseAndExceptionWrapper( new AutoWrapperOptions { IsDebug = true });

现在，当您再次运行该应用程序以触发异常时，它将显示如下内容：

{"isError": true,"responseException": {"exceptionMessage": " Input string was not in a correct format.","details": "   at System.Number.ThrowOverflowOrFormatException(ParsingStatus status, TypeCode type)\r\n   at System.Number.ParseInt32(ReadOnlySpan`1 value, NumberStyles styles, NumberFormatInfo info)\r\n   at System.Convert.ToInt32(String value)\r\n   at AutoWrapperDemo.Controllers.WeatherForecastController.Get() in . . . . . . .,"referenceErrorCode": null,"referenceDocumentLink": null,"validationErrors": null}
}

注意，现在显示了真正的异常消息及其详细信息。

[HttpPost]
public async Task<ApiResponse> Post([FromBody]CreateBandDTO band)
{//Call a method to add a new record to the databasetry{var result = await SampleData.AddNew(band);return new ApiResponse("New record has been created to the database", result, 201);}catch (Exception ex){//TO DO: Log exthrow;}
}

成功运行代码将为您提供以下结果：

{"message": "New record has been created to the database","isError": false,"result": 100
}

ApiResponse对象具有可以设置的以下参数：

ApiResponse(string message, object result = null, int statusCode = 200, string apiVersion = "1.0.0.0")

定义自己的Api异常

throw new ApiException(ModelState.AllErrors());

用于抛出您自己的异常消息

throw new ApiException($"Record with id: {id} does not exist.", 400);

例如，让我们使用ModelState验证来修改POST方法：

[HttpPost]
public async Task<ApiResponse> Post([FromBody]CreateBandDTO band)
{if (ModelState.IsValid){//Call a method to add a new record to the databasetry{var result = await SampleData.AddNew(band);return new ApiResponse("New record has been created to the database", result, 201);}catch (Exception ex){//TO DO: Log exthrow;}}elsethrow new ApiException(ModelState.AllErrors());
}

验证失败时，运行代码将导致如下所示：

{"isError": true,"responseException": {"exceptionMessage": "Request responded with validation error(s). Please correct the specified validation errors and try again.","details": null,"referenceErrorCode": null,"referenceDocumentLink": null,"validationErrors": [{"field": "Name","message": "The Name field is required."}]}
}

查看如何使用模型中的违规字段自动填充validationErrors属性。

ApiException(string message, int statusCode = 500, string errorCode = "", string refLink = "")
ApiException(IEnumerable<ValidationError> errors, int statusCode = 400)
ApiException(System.Exception ex, int statusCode = 500)

选项

app.UseApiResponseAndExceptionWrapper(new AutoWrapperOptions { ShowApiVersion = true });

默认API 版本格式设置为“ 1.0.0.0”

app.UseApiResponseAndExceptionWrapper(new AutoWrapperOptions { ShowApiVersion = true, ApiVersion = "2.0"
});

ShowStatusCode

app.UseApiResponseAndExceptionWrapper(new AutoWrapperOptions { ShowStatusCode = true });

IsDebug

app.UseApiResponseAndExceptionWrapper(new AutoWrapperOptions { IsDebug = true }); 

IsApiOnly

app.UseApiResponseAndExceptionWrapper(new AutoWrapperOptions { IsApiOnly = false} );

WrapWhenApiPathStartsWith

app.UseApiResponseAndExceptionWrapper(new AutoWrapperOptions { IsApiOnly = false, WrapWhenApiPathStartsWith = "/myapi"
});

当请求路径包含WrapWhenApiPathStartsWith值时，这将激活AutoWrapper 来拦截HTTP响应。