feat: Enhance user update handling and introduce NullString type for optional fields

backend/internal/api/handlers/user_handler.go

@@ -163,11 +163,38 @@ func (h *UserHandler) UpdateUser(c *gin.Context) {
 	// Set ID from URL
 	userUpdateDTO.ID = id.String()
 
-	// Convert DTO to model
-	userUpdate := convertUpdateDTOToModel(userUpdateDTO)
+	// Set ID from URL
+	userUpdateDTO.ID = id.String()
+
+	// Convert DTO to Model
+	idWrapper := models.FromULID(id)
+	update := models.UserUpdate{
+		ID: idWrapper,
+	}
+
+	if userUpdateDTO.Email != nil {
+		update.Email = userUpdateDTO.Email
+	}
+	if userUpdateDTO.Password != nil {
+		update.Password = userUpdateDTO.Password
+	}
+	if userUpdateDTO.Role != nil {
+		update.Role = userUpdateDTO.Role
+	}
+	if userUpdateDTO.CompanyID != nil {
+		companyID, err := models.ULIDWrapperFromString(*userUpdateDTO.CompanyID)
+		if err != nil {
+			utils.BadRequestResponse(c, "Invalid company ID format")
+			return
+		}
+		update.CompanyID = &companyID
+	}
+	if userUpdateDTO.HourlyRate != nil {
+		update.HourlyRate = userUpdateDTO.HourlyRate
+	}
 
 	// Update user in the database
-	user, err := models.UpdateUser(c.Request.Context(), userUpdate)
+	user, err := models.UpdateUser(c.Request.Context(), update)
 	if err != nil {
 		utils.InternalErrorResponse(c, "Error updating user: "+err.Error())
 		return
@@ -348,20 +375,27 @@ func (h *UserHandler) GetCurrentUser(c *gin.Context) {
 // Helper functions for DTO conversion
 
 func convertUserToDTO(user *models.User) dto.UserDto {
+	var companyID *string
+	if user.CompanyID != nil {
+		s := user.CompanyID.String()
+		companyID = &s
+	}
 	return dto.UserDto{
 		ID:         user.ID.String(),
 		CreatedAt:  user.CreatedAt,
 		UpdatedAt:  user.UpdatedAt,
 		Email:      user.Email,
 		Role:       user.Role,
-		CompanyID:  user.CompanyID.String(),
+		CompanyID:  companyID,
 		HourlyRate: user.HourlyRate,
 	}
 }
 
 func convertCreateDTOToModel(dto dto.UserCreateDto) models.UserCreate {
-	// Convert CompanyID from int to ULID (this is a simplification, adjust as needed)
-	companyID, _ := models.ULIDWrapperFromString(dto.CompanyID)
+	var companyID models.ULIDWrapper
+	if dto.CompanyID != nil {
+		companyID, _ = models.ULIDWrapperFromString(*dto.CompanyID) // Ignoring error, validation happens in the model
+	}
 
 	return models.UserCreate{
 		Email:      dto.Email,
@@ -371,34 +405,3 @@ func convertCreateDTOToModel(dto dto.UserCreateDto) models.UserCreate {
 		HourlyRate: dto.HourlyRate,
 	}
 }
-
-func convertUpdateDTOToModel(dto dto.UserUpdateDto) models.UserUpdate {
-	id, _ := ulid.Parse(dto.ID)
-	update := models.UserUpdate{
-		ID: models.FromULID(id),
-	}
-
-	if dto.Email != nil {
-		update.Email = dto.Email
-	}
-
-	if dto.Password != nil {
-		update.Password = dto.Password
-	}
-
-	if dto.Role != nil {
-		update.Role = dto.Role
-	}
-
-	if dto.CompanyID != nil {
-		// Convert CompanyID from int to ULID (this is a simplification, adjust as needed)
-		companyID, _ := models.ULIDWrapperFromString(*dto.CompanyID)
-		update.CompanyID = &companyID
-	}
-
-	if dto.HourlyRate != nil {
-		update.HourlyRate = dto.HourlyRate
-	}
-
-	return update
-}