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之前写过使用自定义返回类的方式来统一接口数据返回格式，.Net Core webapi RestFul 统一接口数据返回格式-CSDN博客

但是这存在一个问题，不是所有接口会按照定义的数据格式返回，除非每个接口都返回我们自定义的类，这种实现起来不太现实。

类似这样，定义一个接口：

返回的只是只有user的json对象：

这显然不是我们想要的结果，我们想要的结果是这样：

{"statusCode": 200,"successful": true,"message": null,"data": {"userId": "001","userName": "小王","password": "123"}
}

我们需要不管接口定义的返回类型是什么，最后的结果都是统一的数据格式，需要实现这个功能就需要自定义一个过滤器来实现。

具体实现代码如下：

自定义一个过滤器类 ResponseWrapperFilter.cs

public class ResponseWrapperFilter : IAsyncResultFilter{public async Task OnResultExecutionAsync(ResultExecutingContext context, ResultExecutionDelegate next){if (context.Result is ObjectResult objectResult){if (objectResult.Value is IApiResponse apiResponse){objectResult.StatusCode = apiResponse.StatusCode;context.HttpContext.Response.StatusCode = apiResponse.StatusCode;}else{var statusCode = objectResult.StatusCode ?? context.HttpContext.Response.StatusCode;var wrapperResp = new ApiResponse<object>{StatusCode = statusCode,Successful = statusCode is >= 200 and < 400,Data = objectResult.Value,};objectResult.Value = wrapperResp;objectResult.DeclaredType = wrapperResp.GetType();}}await next();}}

在代码中进行判断，当响应的类型是 ObjectResult 时，把这个响应结果拿出来，再判断是不是 IApiResponse 类型。

前面我们介绍过，所有 ApiResponse 都实现了 IApiResponse 这个接口，所以可以判断是不是 IApiResponse 类型来确定这个返回结果是否包装过。

没包装的话就给包装一下，就这么简单。

附上 ApiResponse.cs  IApiResponse.cs 代码

    public interface IApiResponse{public int StatusCode { get; set; }public bool Successful { get; set; }public string? Message { get; set; }}public interface IApiResponse<T> : IApiResponse{public T? Data { get; set; }}public interface IApiErrorResponse{public Dictionary<string, object> ErrorData { get; set; }}public class ApiResponse<T> : IApiResponse<T>{public ApiResponse(){}public ApiResponse(T? data){Data = data;}public int StatusCode { get; set; } = 200;public bool Successful { get; set; } = true;public string? Message { get; set; }public T? Data { get; set; }/// <summary>/// 实现将 <see cref="ApiResponse"/> 隐式转换为 <see cref="ApiResponse{T}"/>/// </summary>/// <param name="apiResponse"><see cref="ApiResponse"/></param>public static implicit operator ApiResponse<T>(ApiResponse apiResponse){return new ApiResponse<T>{StatusCode = apiResponse.StatusCode,Successful = apiResponse.Successful,Message = apiResponse.Message};}}public class ApiResponse : IApiResponse, IApiErrorResponse{public int StatusCode { get; set; } = 200;public bool Successful { get; set; } = true;public string? Message { get; set; }public object? Data { get; set; }/// <summary>/// 可序列化的错误/// <para>用于保存模型验证失败的错误信息</para>/// </summary>public Dictionary<string, object>? ErrorData { get; set; }public ApiResponse(){}public ApiResponse(object data){Data = data;}public static ApiResponse NoContent(string message = "NoContent"){return new ApiResponse{StatusCode = StatusCodes.Status204NoContent,Successful = true,Message = message};}public static ApiResponse Ok(string message = "Ok"){return new ApiResponse{StatusCode = StatusCodes.Status200OK,Successful = true,Message = message};}public static ApiResponse Ok(object data, string message = "Ok"){return new ApiResponse{StatusCode = StatusCodes.Status200OK,Successful = true,Message = message,Data = data};}public static ApiResponse Unauthorized(string message = "Unauthorized"){return new ApiResponse{StatusCode = StatusCodes.Status401Unauthorized,Successful = false,Message = message};}public static ApiResponse NotFound(string message = "NotFound"){return new ApiResponse{StatusCode = StatusCodes.Status404NotFound,Successful = false,Message = message};}public static ApiResponse BadRequest(string message = "BadRequest"){return new ApiResponse{StatusCode = StatusCodes.Status400BadRequest,Successful = false,Message = message};}public static ApiResponse BadRequest(ModelStateDictionary modelState, string message = "ModelState is not valid."){return new ApiResponse{StatusCode = StatusCodes.Status400BadRequest,Successful = false,Message = message,ErrorData = new SerializableError(modelState)};}public static ApiResponse Error(string message = "Error", Exception? exception = null){object? data = null;if (exception != null){data = new{exception.Message,exception.Data};}return new ApiResponse{StatusCode = StatusCodes.Status500InternalServerError,Successful = false,Message = message,Data = data};}}

之后在 Program.cs 里注册一下这个过滤器

services.AddControllers(options =>
{options.Filters.Add<ResponseWrapperFilter>();
});

再次调用GetUser接口，可以看到已经包装成统一的数据格式返回了：

而对于之前已经定义返回类型是ApiResponse的接口也不会重复包装：