Fix context usage (#33554)

Some old code use direct type-casting to get context, it causes
problems.

This PR fixes all legacy problems and use correct `ctx.Value` to get
low-level contexts.

Fix #33518

services/context/context.go

@@ -79,9 +79,9 @@ type webContextKeyType struct{}
 
 var WebContextKey = webContextKeyType{}
 
-func GetWebContext(req *http.Request) *Context {
-	ctx, _ := req.Context().Value(WebContextKey).(*Context)
-	return ctx
+func GetWebContext(ctx context.Context) *Context {
+	webCtx, _ := ctx.Value(WebContextKey).(*Context)
+	return webCtx
 }
 
 // ValidateContext is a special context for form validation middleware. It may be different from other contexts.
@@ -135,6 +135,7 @@ func NewWebContext(base *Base, render Render, session session.Store) *Context {
 	}
 	ctx.TemplateContext = NewTemplateContextForWeb(ctx)
 	ctx.Flash = &middleware.Flash{DataStore: ctx, Values: url.Values{}}
+	ctx.SetContextValue(WebContextKey, ctx)
 	return ctx
 }
 
@@ -165,7 +166,7 @@ func Contexter() func(next http.Handler) http.Handler {
 			ctx.PageData = map[string]any{}
 			ctx.Data["PageData"] = ctx.PageData
 
-			ctx.Base.SetContextValue(WebContextKey, ctx)
+			ctx.Base.SetContextValue(WebContextKey, ctx) // FIXME: this should be removed because NewWebContext should already set it
 			ctx.Csrf = NewCSRFProtector(csrfOpts)
 
 			// get the last flash message from cookie

services/context/package.go

@@ -156,7 +156,7 @@ func PackageContexter() func(next http.Handler) http.Handler {
 			base := NewBaseContext(resp, req)
 			// it is still needed when rendering 500 page in a package handler
 			ctx := NewWebContext(base, renderer, nil)
-			ctx.SetContextValue(WebContextKey, ctx)
+			ctx.SetContextValue(WebContextKey, ctx) // FIXME: this should be removed because NewWebContext should already set it
 			next.ServeHTTP(ctx.Resp, ctx.Req)
 		})
 	}