.NET Core AutoWrapper 自定义响应输出

前言

AutoWrapper是一个简单可自定义全局异常处理程序和ASP.NET Core API响应的包装。他使用ASP.NET Core middleware拦截传入的HTTP请求，并将最后的结果使用统一的格式来自动包装起来.目的主要是让我们更多的关注业务特定的代码要求，并让包装器自动处理HTTP响应。这可以在构建API时加快开发时间，同时为HTTP响应试试我们统一的标准。

安装

AutoWrapper.Core从NuGet或通过CLI下载并安装

PM> Install-Package AutoWrapper.Core

在Startup.cs Configure方法中注册以下内容，但是切记要放在UseRouting前

app.UseApiResponseAndExceptionWrapper();

启动属性映射

默认情况下AutoWrapper将在成功请求成功时输出以下格式：

{
    "message": "Request successful.",
    "isError": false,
    "result": [
      {
        "id": 7002,
        "firstName": "Vianne",
        "lastName": "Durano",
        "dateOfBirth": "2018-11-01T00:00:00"
      }
    ]
}

如果说不喜欢默认属性命名方式，那么我们可以通过AutoWrapperPropertyMap属性进行映射为我们需要指定的任何名称。例如我么可以将result属性的名称更改为data。如下所示

public class MapResponseObject  
{
    [AutoWrapperPropertyMap(Prop.Result)]
    public object Data { get; set; }
}

然后将MapResponseObject类传递给AutpWrapper middleware

app.UseApiResponseAndExceptionWrapper<MapResponseObject>();

通过映射重新请求后，现在影响格式如下所示

{
    "message": "Request successful.",
    "isError": false,
    "data": {
        "id": 7002,
        "firstName": "Vianne",
        "lastName": "Durano",
        "dateOfBirth": "2018-11-01T00:00:00"
    }
}

可以从中看出result属性已经更换为data属性了

默认情况下AutoWrapper发生异常时将吐出以下响应格式

{
    "isError": true,
    "responseException": {
        "exceptionMessage": "Unhandled Exception occurred. Unable to process the request."
    }
}

而且如果在AutoWrapperOptions中设置了IsDebug，则将产生带有堆栈跟踪信息的类似信息

{
    "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 …"
    }
}

如果想将某些APIError属性名称更改为其他名称，只需要在以下代码中添加以下映射MapResponseObject

public class MapResponseObject  
{
    [AutoWrapperPropertyMap(Prop.ResponseException)]
    public object Error { get; set; }

    [AutoWrapperPropertyMap(Prop.ResponseException_ExceptionMessage)]
    public string Message { get; set; }

    [AutoWrapperPropertyMap(Prop.ResponseException_Details)]
    public string StackTrace { get; set; }
}

通过如下代码来模拟错误

int num = Convert.ToInt32("10s");

现在映射后的输出如下所示

{
    "isError": true,
    "error": {
        "message": " Input string was not in a correct format.",
        "stackTrace": "   at System.Number.ThrowOverflowOrFormatException(ParsingStatus status, TypeCode type)\r\n   at System.Number.ParseInt32(ReadOnlySpan`1 value, NumberStyles styles, NumberFormatInfo info)\r\n …"
    }
}

请注意APIError现在根据MapResponseObject类中定义的属性更改了模型的默认属性。

我们可以自由的选择映射任何属性，下面是映射属性相对应的列表

[AutoWrapperPropertyMap(Prop.Version)]
[AutoWrapperPropertyMap(Prop.StatusCode)]
[AutoWrapperPropertyMap(Prop.Message)]
[AutoWrapperPropertyMap(Prop.IsError)]
[AutoWrapperPropertyMap(Prop.Result)]
[AutoWrapperPropertyMap(Prop.ResponseException)]
[AutoWrapperPropertyMap(Prop.ResponseException_ExceptionMessage)]
[AutoWrapperPropertyMap(Prop.ResponseException_Details)]
[AutoWrapperPropertyMap(Prop.ResponseException_ReferenceErrorCode)]
[AutoWrapperPropertyMap(Prop.ResponseException_ReferenceDocumentLink)]
[AutoWrapperPropertyMap(Prop.ResponseException_ValidationErrors)]
[AutoWrapperPropertyMap(Prop.ResponseException_ValidationErrors_Field)]
[AutoWrapperPropertyMap(Prop.ResponseException_ValidationErrors_Message)]

自定义错误架构

AutoWrapper还提供了一个APIException可用于定义自己的异常的对象，如果想抛出自己的异常消息，则可以简单地执行以下操作

throw new ApiException("Error blah", 400, "511", "http://blah.com/error/511");

默认输出格式如下所示

{
    "isError": true,
    "responseException": {
        "exceptionMessage": "Error blah",
        "referenceErrorCode": "511",
        "referenceDocumentLink": "http://blah.com/error/511"
    }
}

当然我们可以自定义错误格式

public class MapResponseObject  
{
    [AutoWrapperPropertyMap(Prop.ResponseException)]
    public object Error { get; set; }
}

public class Error  
{
    public string Message { get; set; }

    public string Code { get; set; }
    public InnerError InnerError { get; set; }

    public Error(string message, string code, InnerError inner)
    {
        this.Message = message;
        this.Code = code;
        this.InnerError = inner;
    }

}

public class InnerError  
{
    public string RequestId { get; set; }
    public string Date { get; set; }

    public InnerError(string reqId, string reqDate)
    {
        this.RequestId = reqId;
        this.Date = reqDate;
    }
}

然后我们可以通过如下代码进行引发我们错误

throw new ApiException(  
      new Error("An error blah.", "InvalidRange",
      new InnerError("12345678", DateTime.Now.ToShortDateString())
));

输出格式如下所示

{
    "isError": true,
    "error": {
        "message": "An error blah.",
        "code": "InvalidRange",
        "innerError": {
            "requestId": "12345678",
            "date": "10/16/2019"
        }
    }
}

使用自定义API响应格式

如果映射满足不了我们的需求。并且我们需要向API响应模型中添加其他属性，那么我们现在可以自定义自己的格式类，通过设置UseCustomSchema为true来实现，代码如下所示

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

现在假设我们想在主API中响应中包含一个属性SentDate和Pagination对象，我们可能希望将API响应模型定义为以下格式

public class MyCustomApiResponse  
{
    public int Code { get; set; }
    public string Message { get; set; }
    public object Payload { get; set; }
    public DateTime SentDate { get; set; }
    public Pagination Pagination { get; set; }

    public MyCustomApiResponse(DateTime sentDate, object payload = null, string message = "", int statusCode = 200, Pagination pagination = null)
    {
        this.Code = statusCode;
        this.Message = message == string.Empty ? "Success" : message;
        this.Payload = payload;
        this.SentDate = sentDate;
        this.Pagination = pagination;
    }

    public MyCustomApiResponse(DateTime sentDate, object payload = null, Pagination pagination = null)
    {
        this.Code = 200;
        this.Message = "Success";
        this.Payload = payload;
        this.SentDate = sentDate;
        this.Pagination = pagination;
    }

    public MyCustomApiResponse(object payload)
    {
        this.Code = 200;
        this.Payload = payload;
    }

}

public class Pagination  
{
    public int TotalItemsCount { get; set; }
    public int PageSize { get; set; }
    public int CurrentPage { get; set; }
    public int TotalPages { get; set; }
}

通过如下代码片段进行测试结果

public async Task<MyCustomApiResponse> Get()  
{
    var data = await _personManager.GetAllAsync();

    return new MyCustomApiResponse(DateTime.UtcNow, data,
        new Pagination
        {
            CurrentPage = 1,
            PageSize = 10,
            TotalItemsCount = 200,
            TotalPages = 20
        });

}

运行后会得到如下影响格式

{
    "code": 200,
    "message": "Success",
    "payload": [
        {
            "id": 1,
            "firstName": "Vianne",
            "lastName": "Durano",
            "dateOfBirth": "2018-11-01T00:00:00"
        },
        {
            "id": 2,
            "firstName": "Vynn",
            "lastName": "Durano",
            "dateOfBirth": "2018-11-01T00:00:00"
        },
        {
            "id": 3,
            "firstName": "Mitch",
            "lastName": "Durano",
            "dateOfBirth": "2018-11-01T00:00:00"
        }
    ],
    "sentDate": "2019-10-17T02:26:32.5242353Z",
    "pagination": {
        "totalItemsCount": 200,
        "pageSize": 10,
        "currentPage": 1,
        "totalPages": 20
    }
}

但是从这里要注意一旦我们对API响应进行自定义，那么就代表我们完全控制了要格式化数据的方式，同时丢失了默认API响应的某些选项配置。但是我们仍然可以利用ApiException()方法引发用户定义的错误消息
如下所示

[Route("{id:long}")]
[HttpPut]
public async Task<MyCustomApiResponse> Put(long id, [FromBody] PersonDTO dto)  
{
    if (ModelState.IsValid)
    {
        try
        {
            var person = _mapper.Map<Person>(dto);
            person.ID = id;

            if (await _personManager.UpdateAsync(person))
                return new MyCustomApiResponse(DateTime.UtcNow, true, "Update successful.");
            else
                throw new ApiException($"Record with id: {id} does not exist.", 400);
        }
        catch (Exception ex)
        {
            _logger.Log(LogLevel.Error, ex, "Error when trying to update with ID:{@ID}", id);
            throw;
        }
    }
    else
        throw new ApiException(ModelState.AllErrors());
}

现在当进行模型验证时，可以获得默认响应格式

{
    "isError": true,
    "responseException": {
        "exceptionMessage": "Request responded with validation error(s). Please correct the specified validation errors and try again.",
        "validationErrors": [
            {
                "field": "FirstName",
                "message": "'First Name' must not be empty."
            }
        ]
    }
}