refac: article title rules are the same in the API request and the domain; an invalid title returns 400 instead of 500

internal/domain/article/articleDomain.go

@@ -4,6 +4,7 @@ import (
 	domain "RenewCMS/internal/domain/image"
 	"errors"
 	"time"
+	"unicode/utf8"
 )
 
 var (
@@ -12,6 +13,19 @@ var (
 	ErrArticleOffline  = errors.New("article is offline")
 )
 
+const (
+	MinTitleRunes = 3
+	MaxTitleRunes = 200
+)
+
+func ValidateTitle(title string) error {
+	runeCount := utf8.RuneCountInString(title)
+	if runeCount < MinTitleRunes || runeCount > MaxTitleRunes {
+		return ErrInvalidTitle
+	}
+	return nil
+}
+
 type Article struct {
 	ID        uint32          `json:"id"`
 	Title     string          `json:"title"`

internal/infrastructure/useCases/CreateArticle.go

@@ -18,8 +18,8 @@ func NewCreateArticleUseCase(articleRepository article.Repository) *CreateArticl
 }
 
 func (g *CreateArticleUseCase) CreateArticle(createArticle CreateArticleCommand) (article.Article, error) {
-	if len(createArticle.Title) < 3 || len(createArticle.Title) > 200 {
-		return article.Article{}, article.ErrInvalidTitle
+	if err := article.ValidateTitle(createArticle.Title); err != nil {
+		return article.Article{}, err
 	}
 
 	return g.articleRepository.Create(article.Article{