【ASP.NET Core】MVC过滤器：常见用法

public class GameController : ControllerBase
{
    [HttpGet("game/play")]
    public string Play(Game g)
    {
        if(ModelState.IsValid == false)
        {
            return "你玩个寂寞";
        }
        return $"你正在玩{g.Year}年出的《{g.GameName}》游戏";
    }
}

public class Game
{
    /// 

    /// 游戏序列号
    /// 
    public string? GameSerial { get; set; }

    /// 

    /// 游戏名称
    /// 
    public string? GameName { get; set; }

    /// 

    /// 谁发行的
    /// 
    public string? Publisher { get; set; }

    /// 

    /// 哪一年发行的
    /// 
服务器托管网    public int Year { get; set; }
}

app.MapGet("/", async (HttpContext context) =>
{
    string html = """
    
    
        
            
            
                label {
                    min-width: 100px;
                    display: inline-block;
                }
            
        
        
            

                for="gserial">游戏序列号：
                "gserial" type="text" />
            
            

                for="gname">游戏名称：
                "gname" type="text" />
            
            

                for="pub">发行者：
                "text" id="pub" />
            
            

                for="year">发行年份：
                "year" type="text"/>
            
            

                "reqTest()">确定
            
            
"res">

            
                function reqTest() {
                    let serial= document.getElementById("gserial").value;
                    let name = document.getElementById("gname").value;
                    let pub = document.getElementById("pub").value;
                    let year = parseInt(document.getElementById("year").value, 10);
                    let result = document.getElementById("res");
                    const url = `/game/play?gameSerial=${serial}&gamename=${name}&publisher=${pub}&year=${year}`;
                    fetch(url, { method: "GET" })
                        .then(response => {
                            response.text().then(txt => {
                                result.innerHTML = txt;
                            });
                        });
                }
            
        
    
    """;
    var response = context.Response;
    response.Headers.ContentType = "text/html; charset=UTF-8";
    await response.WriteAsync(html);
});

你正在玩2022年出的《法外狂徒大冒险》游戏

using Microsoft.AspNetCore.Mvc.Filters;
using Microsoft.AspNetCore.Mvc.ModelBinding;

public class RemoveQueryStringProviderFilter : IResourceFilter
{
    public void OnResourceExecuted(ResourceExecutedContext context)
    {
        // 空空如也
    }

    public void OnResourceExecuting(ResourceExecutingContext context)
    {
        var qsValueProviders = context.ValueProviderFactories.OfType();
        if (qsValueProviders != null && qsValueProviders.Any())
        {
            context.ValueProviderFactories.RemoveType();
        }
    }
}

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddControllers(options =>
{
    options.Filters.Add();
});
var app = builder.Build();

你正在玩0年出的《》游戏

[AttributeUsage(AttributeTargets.Method, AllowMultiple = false)]
public class CustExceptionFilterAttribute : Attribute, IExceptionFilter
{
    public void OnException(ExceptionContext context)
    {
        // 看看有没有异常
        if (context.Exception is null || context.ExceptionHandled)
            return;
        // 有异常哦，修改一下返回结果
        ContentResult result = new();
        result.Content = "出错啦，伙计。错误消息：" + context.Exception.Message;
        // 设置返回结果
        context.Result = result;
        // 标记异常已处理
        context.ExceptionHandled = true;
    }
}

public class AbcController : ControllerBase
{
    [HttpGet("calc/add"), CustExceptionFilter]
    public int Add(int x, int y)
    {
        int r = x + y;
        if(r >= 1000)
        {
            throw new Exception("计算结果必须在1000以内");
        }
        return r;
    }
}

public class SetCookieResultFilter : IResultFilter
{
    public void OnResultExecuted(ResultExecutedContext context)
    {
        // 不能在这里写 Cookie
    }

    public void OnResultExecuting(ResultExecutingContext context)
    {
        HttpResponse response = context.HttpContext.Response;
        // 设置Cookie
        response.Cookies.Append("X-VER", "3.0");
    }
}

public class DemoController : ControllerBase
{
    [HttpGet("abc/test")]
    public string Work() => "山重水复疑无路";
}

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddControllers(options =>
{
    options.Filters.Add();
});
var app = builder.Build();