From dee7a13cbafd6a1248233b75ad9b2f91d0745cc0 Mon Sep 17 00:00:00 2001
From: mikestefanello <mike.stefanello@gmail.com>
Date: Tue, 14 Dec 2021 20:54:47 -0500
Subject: [PATCH] Add support for better validation error messages.

---
 controller/controller.go | 30 ++++++++++++++++++++++++++++++
 routes/login.go          |  6 +++---
 2 files changed, 33 insertions(+), 3 deletions(-)

diff --git a/controller/controller.go b/controller/controller.go
index eaf41e2..3f5335e 100644
--- a/controller/controller.go
+++ b/controller/controller.go
@@ -7,6 +7,7 @@ import (
 	"net/http"
 	"path"
 	"path/filepath"
+	"reflect"
 	"runtime"
 	"sync"
 
@@ -14,6 +15,9 @@ import (
 	"goweb/container"
 	"goweb/funcmap"
 	"goweb/middleware"
+	"goweb/msg"
+
+	"github.com/go-playground/validator/v10"
 
 	"github.com/eko/gocache/v2/marshaler"
 
@@ -151,6 +155,32 @@ func (t *Controller) Redirect(c echo.Context, route string, routeParams ...inter
 	return c.Redirect(http.StatusFound, c.Echo().Reverse(route, routeParams))
 }
 
+func (t *Controller) SetValidationErrorMessages(c echo.Context, err error, data interface{}) {
+	for _, ve := range err.(validator.ValidationErrors) {
+		var message string
+
+		// Default the field label to the name of the struct field
+		label := ve.StructField()
+
+		// Attempt to get a label from the field's struct tag
+		if field, ok := reflect.TypeOf(data).FieldByName(ve.Field()); ok {
+			if labelTag := field.Tag.Get("label"); labelTag != "" {
+				label = labelTag
+			}
+		}
+
+		// Provide better error messages depending on the failed validation tag
+		switch ve.Tag() {
+		case "required":
+			message = "%s is required."
+		default:
+			message = "%s is not a valid value."
+		}
+
+		msg.Danger(c, fmt.Sprintf(message, label))
+	}
+}
+
 // getTemplatesDirectoryPath gets the templates directory path
 // This is needed incase this is called from a package outside of main,
 // such as testing
diff --git a/routes/login.go b/routes/login.go
index e418fea..bfb99a5 100644
--- a/routes/login.go
+++ b/routes/login.go
@@ -19,8 +19,8 @@ type (
 	}
 
 	LoginForm struct {
-		Username string `form:"username" validate:"required"`
-		Password string `form:"password" validate:"required"`
+		Username string `form:"username" validate:"required" label:"Username"`
+		Password string `form:"password" validate:"required" label:"Password"`
 	}
 )
 
@@ -47,7 +47,7 @@ func (l *Login) Post(c echo.Context) error {
 
 	// Validate the form
 	if err := c.Validate(l.form); err != nil {
-		msg.Danger(c, "All fields are required.")
+		l.SetValidationErrorMessages(c, err, l.form)
 		return l.Get(c)
 	}