Gin Different 404 handler for different group

Description

I have an api group, and I want it to have a different 404 handler than the main group. I want to do something like this:

r.Group("/a").NoRoute(func(ctx *gin.Context) {
    // manage no route for /a
})
r.Group("/b").NoRoute(func(ctx *gin.Context) {
    // manage no route for /b
})

But it is not possible with current RouterGroup

I don't want use workaround explained here #2999, since I want to compose handler func with ctx.Next(), ctx.Abort() and other complex things.

Comment From: JimChenWYU

Base on the current structure of gin, I dont think gin can solve your problem.

Just group by prefix

All routes will be registered to engine.Handlers

So only provides the global 404 handler

Comment From: jerome-laforge

Thanks for this confirmation @JimChenWYU

Comment From: jerome-laforge

I won't use gin.NoRoute(), instead of I will use this workaround:

func noRoute(r *gin.Engine, basePath string, hfs ...gin.HandlerFunc) {
    r.Any(basePath+"/:path", hfs...)
}
...
noRoute(r, "/a", func(ctx *gin.Context) {
    // manage no route for /a/*
})
noRoute(r, "/b", func(ctx *gin.Context) {
    // manage no route for /b/*
})

Thx again @JimChenWYU for your support

Comment From: jerome-laforge

Another workaround that is more robust but also more weird, it is use 2 gin.Engine for each group (the global mergeEngine & the specific engineOnlyForA or engineOnlyForB)

mergeEngine := gin.New()

// manage all routes + noroutes for /a/*
{
    engineOnlyForA := gin.New()
    engineOnlyForA.GET("/a/bc", func(c *gin.Context) {
        // do stuff for /a/bc
    })
    engineOnlyForA.GET("/a/de", func(c *gin.Context) {
        // do stuff for /a/de
    })
    engineOnlyForA.NoRoute(func(c *gin.Context) {
        // no route for /a/*
    })

    mergeEngine.Any("/a/*path", gin.WrapH(engineOnlyForA))
}

// manage all routes + noroutes for /b/* 
{
    engineOnlyForB := gin.New()
    engineOnlyForB.GET("/b/cd", func(c *gin.Context) {
        // do stuff for /b/cd
    })
    engineOnlyForB.GET("/b/ef", func(c *gin.Context) {
        // do stuff for /b/ef
    })
    engineOnlyForB.NoRoute(func(c *gin.Context) {
        // no route for /b/*
    })

    mergeEngine.Any("/b/*path", gin.WrapH(engineOnlyForB))
}