04-Web-Form add form backend check

controller/home.go

@@ -1,7 +1,6 @@
 package controller
 
 import (
-	"fmt"
 	"net/http"
 
 	"github.com/bonfy/go-mega-code/vm"
@@ -21,17 +20,42 @@ func indexHandler(w http.ResponseWriter, r *http.Request) {
 	templates[tpName].Execute(w, &v)
 }
 
+func check(username, password string) bool {
+	if username == "bonfy" && password == "abc123" {
+		return true
+	}
+	return false
+}
+
 func loginHandler(w http.ResponseWriter, r *http.Request) {
 	tpName := "login.html"
 	vop := vm.LoginViewModelOp{}
 	v := vop.GetVM()
+
 	if r.Method == http.MethodGet {
 		templates[tpName].Execute(w, &v)
 	}
 	if r.Method == http.MethodPost {
 		r.ParseForm()
 		username := r.Form.Get("username")
 		password := r.Form.Get("password")
-		fmt.Fprintf(w, "Username:%s Password:%s", username, password)
+
+		if len(username) < 3 {
+			v.AddError("username must longer than 3")
+		}
+
+		if len(password) < 6 {
+			v.AddError("password must longer than 6")
+		}
+
+		if !check(username, password) {
+			v.AddError("username password not correct, please input again")
+		}
+
+		if len(v.Errs) > 0 {
+			templates[tpName].Execute(w, &v)
+		} else {
+			http.Redirect(w, r, "/", http.StatusSeeOther)
+		}
 	}
 }

templates/content/#.html

@@ -5,4 +5,12 @@ <h1>Login</h1>
         <p><input type="password" name="password" value="" placeholder="Password"></p>
         <p><input type="submit" name="submit" value="Login"></p>
     </form>
+
+    {{if .Errs}}
+    <ul>
+        {{range .Errs}}
+            <li>{{.}}</li>
+         {{end}}
+    </ul>
+    {{end}}
 {{end}}

vm/#.go

@@ -3,6 +3,12 @@ package vm
 // LoginViewModel struct
 type LoginViewModel struct {
 	BaseViewModel
+	Errs []string
+}
+
+// AddError func
+func (v *LoginViewModel) AddError(errs ...string) {
+	v.Errs = append(v.Errs, errs...)
 }
 
 // LoginViewModelOp strutc