Feat(BE-36,37,38,39): finish master data management api

internal/modules/constants/services/constant.service.go

@@ -0,0 +1,26 @@
+package service
+
+import (
+	repository "gitlab.com/mbugroup/lti-api.git/internal/modules/constants/repositories"
+
+	"github.com/go-playground/validator/v10"
+	"github.com/gofiber/fiber/v2"
+)
+
+type ConstantService interface {
+	GetAll(ctx *fiber.Ctx) (map[string]interface{}, error)
+}
+
+type constantService struct {
+	Repository repository.ConstantRepository
+}
+
+func NewConstantService(repo repository.ConstantRepository, validate *validator.Validate) ConstantService {
+	return &constantService{
+		Repository: repo,
+	}
+}
+
+func (s constantService) GetAll(c *fiber.Ctx) (map[string]interface{}, error) {
+	return s.Repository.GetConstants(), nil
+}