.NET7之MiniAPI(特别篇)：.NET7 Preview3

Posted 2022-09-09 teayear

.NET7的第三个预览版发布了，同样带来了mini api的更新，这次带来了路由过滤器，与mvc版的action 过滤器相似。具体见https://devblogs.microsoft.com/dotnet/asp-net-core-updates-in-dotnet-7-preview-3/

用官方的代码，跑不起来，这样那样的问题，比如下面的代码，直接报空引用的异常。

app.MapGet("/data0/no", (string no) =>

    Console.WriteLine($"Get方法中：no=no");
    return new Data  No = no, Name = "test" + DateTime.Now ;

).AddFilter((RouteHandlerInvocationContext context, RouteHandlerFilterDelegate next) =>
    
        var no = (string?)context.Parameters[0];
        Console.WriteLine($"Get方法前：no=no");
        if (no != null && !no.StartsWith("NO"))
        
            return new ValueTask<object?>("no is error!");
        
        var result = next(context);
        if (result.IsCompleted)
        
            Console.WriteLine($"Get方法后：结果=result.Result");
        
        return result;
    );

经过一阵折腾，终于正常的跑了起来，需要把map的方法独立出来写才可以。同时这里使用了三种方式来使用过滤器，换汤不换药，本质一样。

var builder = WebApplication.CreateBuilder(args);

var app = builder.Build();

Data GetData(string no)

    Console.WriteLine($"Get方法中：no=no");
    return new Data  No = no, Name = "test" + DateTime.Now ;
;
//第一种方式
app.MapGet("/data1/no", GetData)
    .AddFilter((RouteHandlerInvocationContext context, RouteHandlerFilterDelegate next) =>
    
        var no = (string?)context.Parameters[0];
        Console.WriteLine($"Get方法前：no=no");
        if (no != null && !no.StartsWith("NO"))
        
            return new ValueTask<object?>("no is error!");
        
        var result = next(context);
        if (result.IsCompleted)
        
            Console.WriteLine($"Get方法后：结果=result.Result");
        
        return result;
    );

string AddTest(Data data)

    Console.WriteLine($"Post方法中：no=data.No");
    return "OK";

app.MapPost("/data1", AddTest)
    .AddFilter((RouteHandlerInvocationContext context, RouteHandlerFilterDelegate next) =>
    
        var data = (Data?)context.Parameters[0];
        Console.WriteLine($"Post方法前：data=data");
        var result = next(context);
        if (result.IsCompleted)
        
            Console.WriteLine($"Post方法后：结果=result.Result");
        
        return result;
    );
//第二种方式
app.MapGet("/data2/no", GetData)
.AddFilter((RouteHandlerContext routeHandlerContext, RouteHandlerFilterDelegate next) =>

    return (context) =>
    
        var no = (string?)context.Parameters[0];
        if (no != null && !no.StartsWith("NO"))
        
            return new ValueTask<object?>("no is error!");
        
        return next(context);
    ;
);
//第三种方式
app.MapGet("/data3/name", GetData).AddFilter<MyFilter>();

app.Run();

public class MyFilter : IRouteHandlerFilter

    public ValueTask<object?> InvokeAsync(RouteHandlerInvocationContext context, RouteHandlerFilterDelegate next)
    
        var no = (string?)context.Parameters[0];
        if (no != null && !no.StartsWith("NO"))
        
            return new ValueTask<object?>("no is error!");
        
        return next(context);
    


public record Data

    public string No  get; set; 
    public string Name  get; set;