c# - 对 ASP.NET Core 中缺少必需属性的响应

Question

给定以下 Controller :

using System.ComponentModel.DataAnnotations;
using Microsoft.AspNetCore.Mvc;

namespace WebApplication1.Controllers
{
    [Route("api/[controller]")]
    [ApiController]
    public class ValuesController : ControllerBase
    {
        // POST api/values
        [HttpPost]
        public ActionResult<string> Post([FromBody] Model req)
        {
            return $"Your name is {req.Name}";
        }
    }

    public class Model
    {
        [Required] public string Name { get; set; }
    }
}

如果我发布一个空主体 {}，响应是:

{
    "errors": {
        "Name": [
            "The Name field is required."
        ]
    },
    "title": "One or more validation errors occurred.",
    "status": 400,
    "traceId": "80000002-0002-ff00-b63f-84710c7967bb"
}

我想更改此响应，以便更轻松地自动将错误消息传递给用户。所以我希望它看起来更像这样:

{
    "error": 999,
    "message": "Field 'name' is required."
}

我尝试像这样扩展 RequiredAttribute 类:

public class MyRequiredAttribute : RequiredAttribute
{
    public MyRequiredAttribute()
    {
        ErrorMessage = "{0} is required";
    }
}

遗憾的是，这只会更改集合中返回的字符串，就像这样

{
    "errors": {
        "Name": [
            "Name is required"
        ]
    },
    "title": "One or more validation errors occurred.",
    "status": 400,
    "traceId": "80000006-0000-ff00-b63f-84710c7967bb"
}

Answer 1

当使用应用了 ApiController 属性的 Controller 时，ASP.NET Core 会自动处理模型验证错误，方法是返回一个 400 Bad Request 并将 ModelState 作为响应主体。与Automatic HTTP 400 responses有关.您可以像下面这样自定义 BadRequest 响应:

  services.AddMvc()
                .ConfigureApiBehaviorOptions(options =>
                {
                    options.InvalidModelStateResponseFactory = actionContext =>
                    {
                        var modelState = actionContext.ModelState;
                        return new BadRequestObjectResult(FormatOutput(modelState));
                    };
                })
                .SetCompatibilityVersion(CompatibilityVersion.Version_2_2);

根据您的想法自定义 FormatOutput 方法。

public List<Base> FormatOutput(ModelStateDictionary input)
    {
        List<Base> baseResult = new List<Base>();
        foreach (var modelState in input.Values)
        {
            foreach (ModelError error in modelState.Errors)
            {
                Base basedata = new Base();
                basedata.Error = StatusCodes.Status400BadRequest;
                basedata.Message =error.ErrorMessage; 
                baseResult.Add(basedata);
            }
        }
        return baseResult;
    }

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