Filter patterns in router

For each user, the Beego app creates a directory under /static/users/ in the form of: /static/users/USER_ID/private and /static/users/USER_ID/public, where USER_ID the ID of each user.

I want to protect the private files so that only the user owning them to be able to access with the use of Filters.

The pattern in router is the following:

beego.InsertFilter("/static/users/:userId([0-9]+)/private/*", beego.BeforeRouter, controllers.ProtectPrivateUploads)

and the filter function is the following:

var ProtectPrivateUploads = func(ctx *context.Context) {
fmt.Println("Protecting content")
}

the relevant URL has the following form:

domain.com/static/users/USERID/private/123135645.png

The problem is that the filter function does not get called at all so I am assuming that I must have done something wrong with the pattern in the router.

Any ideas would be welcomed.

It seems that there is another point of insert for filters beego.BeforeStatic but it is not documented at http://beego.me/docs/mvc/controller/filter.md

by looking the code at https://github.com/astaxie/beego/blob/master/router.go, these are the accepted positions when one can trigger the filter:

const (
    // default filter execution points
    BeforeStatic = iota
    BeforeRouter
    BeforeExec
    AfterExec
    FinishRouter
)

so a valid call in order to trigger a filter for static files could be:

beego.InsertFilter("/static/users/:userId([0-9]+)/private/*", beego.BeforeStatic, controllers.ProtectPrivateUploads)

Update

The session object for the beego.BeforeRouter router position can be obtained using the following function:

sess,_ := beego.GlobalSessions.SessionStart(ctx.ResponseWriter, ctx.Request)

as a result a valid router and filter to protect content under /static/ url would be:

router:

beego.InsertFilter("/static/users/:id([0-9]+)/private/*", beego.BeforeStatic, controllers.ProtectPrivateUploads)

filter:

var ProtectPrivateUploads = func(ctx *context.Context) {
    sess,_ := beego.GlobalSessions.SessionStart(ctx.ResponseWriter, ctx.Request)
    defer sess.SessionRelease(ctx.ResponseWriter)
    ses := sess.Get("sessionid")
    if ses != nil {
       // get user's id from the session and check if the user can access the requested URL
}