change Error from struct to interface for package gvalid;error string update for package gdb

.example/net/ghttp/client/middleware/server.go

@@ -0,0 +1,17 @@
+package main
+
+import (
+	"github.com/gogf/gf/frame/g"
+	"github.com/gogf/gf/net/ghttp"
+)
+
+func main() {
+	s := g.Server()
+	s.Group("/", func(group *ghttp.RouterGroup) {
+		group.ALL("/", func(r *ghttp.Request) {
+			r.Response.Write(r.GetMap())
+		})
+	})
+	s.SetPort(8199)
+	s.Run()
+}