Implemented User Repository in a functional manner by making use of IBMs fp-go package

backend-go/internal/application/services/helpers.go

@@ -0,0 +1,21 @@
+package services
+
+import (
+	"net/http"
+
+	"github.com/gin-gonic/gin"
+)
+
+func HandleError(c *gin.Context) func(error) any {
+	return func(err error) any {
+			c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+			return nil
+	}
+}
+
+func HandleSuccess[T any](c *gin.Context, statusCode int) func(T) any {
+	return func(data T) any {
+			c.JSON(statusCode, data)
+			return nil
+	}
+}

backend-go/internal/application/services/mapper/user_dto_mapper.go

@@ -17,6 +17,15 @@ func MapUserToDTO(user entities.User) dto.UserDTO {
 	}
 }
 
+// MapUsersToDTOs converts a slice of User domain objects to a slice of UserDTOs.
+func MapUsersToDTOs(users []entities.User) []dto.UserDTO {
+	var userDTOs []dto.UserDTO
+	for _, user := range users {
+		userDTOs = append(userDTOs, MapUserToDTO(user))
+	}
+	return userDTOs
+}
+
 // MapCreateDTOToUser converts a UserCreateDTO to a User domain object.
 func MapCreateDTOToUser(dto dto.UserCreateDTO) entities.UserCreate {
 	return entities.UserCreate{

backend-go/internal/application/services/user_service.go

@@ -1,15 +1,16 @@
-package service
+package services
 
 import (
+	"actatempus_backend/internal/application/services/dto"
 	mappers "actatempus_backend/internal/application/services/mapper"
 	"actatempus_backend/internal/domain/entities"
 	"actatempus_backend/internal/domain/repository"
 	"net/http"
 
-	"github.com/gin-gonic/gin"
-
+	A "github.com/IBM/fp-go/array"
 	E "github.com/IBM/fp-go/either"
 	F "github.com/IBM/fp-go/function"
+	"github.com/gin-gonic/gin"
 )
 
 // UserService handles user-related HTTP requests.
@@ -33,71 +34,68 @@ func (s *UserService) RegisterRoutes(router *gin.RouterGroup) {
 
 // CreateUser handles the creation of a new user.
 func (s *UserService) CreateUser(c *gin.Context) {
-	var userCreate entities.UserCreate
-	if err := c.ShouldBindJSON(&userCreate); err != nil {
+	var userCreateDTO dto.UserCreateDTO
+	if err := c.ShouldBindJSON(&userCreateDTO); err != nil {
 		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
 		return
 	}
-
-	s.repository.Create(c.Request.Context(), userCreate).Fold(
-		func(err error) {
-			c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
-		},
-		func(user entities.User) {
-			c.JSON(http.StatusCreated, user)
-		},
+	userCreate := mappers.MapCreateDTOToUser(userCreateDTO)
+	F.Pipe2(
+		s.repository.Create(c.Request.Context(), userCreate),
+		E.Map[error](mappers.MapUserToDTO),
+		E.Fold(
+			HandleError(c),
+			HandleSuccess[dto.UserDTO](c, http.StatusCreated),
+		),
 	)
 }
 
 // GetUserByID handles fetching a user by their ID.
 func (s *UserService) GetUserByID(c *gin.Context) {
 	id := c.Param("id")
-	mappers.MapCreateDTOToProject(id)
-	res := F.Pipe2(
+	F.Pipe2(
 		s.repository.FindByID(c.Request.Context(), id),
-		E.Map(mappers.MapUserToDTO),
-	)
-		
-	s.repository.FindByID(c.Request.Context(), id).Fold(
-		func(err error) {
-			c.JSON(http.StatusNotFound, gin.H{"error": err.Error()})
-		},
-		func(user entities.User) {
-			c.JSON(http.StatusOK, user)
-		},
+		E.Map[error](mappers.MapUserToDTO),
+		E.Fold(
+			HandleError(c),
+			HandleSuccess[dto.UserDTO](c, http.StatusOK),
+		),
 	)
 }
 
 // GetAllUsers handles fetching all users.
 func (s *UserService) GetAllUsers(c *gin.Context) {
-	s.repository.FindAll(c.Request.Context()).Fold(
-		func(err error) {
-			c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
-		},
-		func(users []entities.User) {
-			c.JSON(http.StatusOK, users)
-		},
+	F.Pipe2(
+		s.repository.FindAll(c.Request.Context()),
+		E.Map[error](func(users []entities.User) []dto.UserDTO {
+			return A.Map(mappers.MapUserToDTO)(users) // Anwenden des Mappings auf jedes Element
+		}),
+		E.Fold(
+			HandleError(c),
+			HandleSuccess[[]dto.UserDTO](c, http.StatusOK),
+		),
 	)
 }
 
 // UpdateUser handles updating an existing user.
 func (s *UserService) UpdateUser(c *gin.Context) {
 	id := c.Param("id")
-	var userUpdate entities.UserUpdate
+	var userUpdateDTO dto.UserUpdateDTO
 
-	if err := c.ShouldBindJSON(&userUpdate); err != nil {
+	if err := c.ShouldBindJSON(&userUpdateDTO); err != nil {
 		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
 		return
 	}
 
-	userUpdate.ID = id
-	s.repository.Update(c.Request.Context(), userUpdate).Fold(
-		func(err error) {
-			c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
-		},
-		func(user entities.User) {
-			c.JSON(http.StatusOK, user)
-		},
+	userUpdate := mappers.MapUpdateDTOToUser(userUpdateDTO, id)
+
+	F.Pipe2(
+		s.repository.Update(c.Request.Context(), userUpdate),
+		E.Map[error](mappers.MapUserToDTO),
+		E.Fold(
+			HandleError(c),
+			HandleSuccess[dto.UserDTO](c, http.StatusOK),
+		),
 	)
 }
 
@@ -105,12 +103,13 @@ func (s *UserService) UpdateUser(c *gin.Context) {
 func (s *UserService) DeleteUser(c *gin.Context) {
 	id := c.Param("id")
 
-	s.repository.Delete(c.Request.Context(), id).Fold(
-		func(err error) {
-			c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
-		},
-		func(_ entities.User) {
-			c.JSON(http.StatusOK, gin.H{"message": "User deleted successfully"})
-		},
+	F.Pipe2(
+		s.repository.Delete(c.Request.Context(), id),
+		E.Map[error](mappers.MapUserToDTO),
+		E.Fold(
+			HandleError(c),
+			HandleSuccess[dto.UserDTO](c, http.StatusOK),
+		),
 	)
+
 }