Only option

app/main.go

@@ -72,7 +72,7 @@ func doList(db *gorm.DB) {
 		Alive: &TRUE,
 	}
 
-	certs, err := repo.List(filter, nil, nil)
+	certs, err := repo.List(filter, nil)
 	if err != nil {
 		panic(err)
 	}
@@ -92,7 +92,7 @@ func doGet(db *gorm.DB) {
 		Id: &id,
 	}
 
-	cert, err := repo.Get(filter)
+	cert, err := repo.Get(filter, nil)
 	if err != nil {
 		panic(err)
 	}

app/repository/method_get.go

@@ -7,6 +7,10 @@ import (
 	"gorm.io/gorm/schema"
 )
 
+type GetOptions struct {
+	Only *[]string
+}
+
 type GetMethod[T schema.Tabler] struct {
 	DbConn *gorm.DB
 }
@@ -15,7 +19,7 @@ func (m *GetMethod[T]) Init(dbConn *gorm.DB) {
 	m.DbConn = dbConn
 }
 
-func (m GetMethod[T]) Get(filter interface{}) (*T, error) {
+func (m GetMethod[T]) Get(filter interface{}, options *GetOptions) (*T, error) {
 	var (
 		model T
 	)
@@ -25,6 +29,10 @@ func (m GetMethod[T]) Get(filter interface{}) (*T, error) {
 		return nil, err
 	}
 
+	if options != nil {
+		query = applyOptionOnly(query, options.Only)
+	}
+
 	result := query.First(&model)
 	if result.Error != nil {
 		return nil, result.Error

app/repository/method_list.go

@@ -1,28 +1,16 @@
 package repository
 
 import (
-	"fmt"
 	"repo-pattern/app/repository/smartfilter"
 
 	"gorm.io/gorm"
 	"gorm.io/gorm/schema"
 )
 
-type Pagination struct {
+type ListOptions struct {
-	Offset int
+	Only       *[]string
-	Limit  int
+	Ordering   *[]Order
-}
+	Pagination *Pagination
-
-type OrderDirection string
-
-const (
-	OrderASC  OrderDirection = "ASC"
-	OrderDESC OrderDirection = "DESC"
-)
-
-type Order struct {
-	Field     string
-	Direction OrderDirection
 }
 
 type ListMethod[T schema.Tabler] struct {
@@ -33,36 +21,7 @@ func (m *ListMethod[T]) Init(dbConn *gorm.DB) {
 	m.DbConn = dbConn
 }
 
-func applyOrdering(query *gorm.DB, ordering *[]Order) *gorm.DB {
+func (m ListMethod[T]) List(filter interface{}, options *ListOptions) (*[]T, error) {
-	if ordering == nil || len(*ordering) == 0 {
-		return query
-	}
-
-	for _, order := range *ordering {
-		if order.Direction == OrderASC {
-			query = query.Order(order.Field)
-		} else {
-			query = query.Order(fmt.Sprintf("%s %s", order.Field, order.Direction))
-		}
-	}
-	return query
-}
-
-func applyPagination(query *gorm.DB, pagination *Pagination) *gorm.DB {
-	if pagination == nil {
-		return query
-	}
-
-	if pagination.Limit != 0 {
-		query = query.Limit(pagination.Limit)
-	}
-	if pagination.Offset != 0 {
-		query = query.Offset(pagination.Offset)
-	}
-	return query
-}
-
-func (m ListMethod[T]) List(filter interface{}, ordering *[]Order, pagination *Pagination) (*[]T, error) {
 	var (
 		model  T
 		models []T
@@ -73,8 +32,11 @@ func (m ListMethod[T]) List(filter interface{}, ordering *[]Order, pagination *P
 		return nil, err
 	}
 
-	query = applyOrdering(query, ordering)
+	if options != nil {
-	query = applyPagination(query, pagination)
+		query = applyOptionOnly(query, options.Only)
+		query = applyOptionOrdering(query, options.Ordering)
+		query = applyOptionPagination(query, options.Pagination)
+	}
 
 	query.Find(&models)
 	return &models, nil

app/repository/options.go

@@ -0,0 +1,61 @@
+package repository
+
+import (
+	"fmt"
+
+	"gorm.io/gorm"
+)
+
+type Pagination struct {
+	Offset int
+	Limit  int
+}
+
+type OrderDirection string
+
+const (
+	OrderASC  OrderDirection = "ASC"
+	OrderDESC OrderDirection = "DESC"
+)
+
+type Order struct {
+	Field     string
+	Direction OrderDirection
+}
+
+func applyOptionOnly(query *gorm.DB, only *[]string) *gorm.DB {
+	if only == nil || len(*only) == 0 {
+		return query
+	}
+	query = query.Select(*only)
+	return query
+}
+
+func applyOptionOrdering(query *gorm.DB, ordering *[]Order) *gorm.DB {
+	if ordering == nil || len(*ordering) == 0 {
+		return query
+	}
+
+	for _, order := range *ordering {
+		if len(order.Direction) == 0 || order.Direction == OrderASC {
+			query = query.Order(order.Field)
+		} else {
+			query = query.Order(fmt.Sprintf("%s %s", order.Field, order.Direction))
+		}
+	}
+	return query
+}
+
+func applyOptionPagination(query *gorm.DB, pagination *Pagination) *gorm.DB {
+	if pagination == nil {
+		return query
+	}
+
+	if pagination.Limit != 0 {
+		query = query.Limit(pagination.Limit)
+	}
+	if pagination.Offset != 0 {
+		query = query.Offset(pagination.Offset)
+	}
+	return query
+}

app/repository/repository_test.go

@@ -56,7 +56,8 @@ func TestListMethod(t *testing.T) {
 		repo.Init(db)
 
 		filter := MyModelFilter{}
-		ordering := []Order{
+		options := ListOptions{
+			Ordering: &[]Order{
 				{
 					Field:     "id",
 					Direction: OrderASC,
@@ -65,12 +66,13 @@ func TestListMethod(t *testing.T) {
 					Field:     "count",
 					Direction: OrderDESC,
 				},
+			},
 		}
 
 		sql := "SELECT * FROM my_models ORDER BY id,count DESC"
 		mock.ExpectQuery(fmt.Sprintf("^%s$", regexp.QuoteMeta(sql)))
 
-		_, err := repo.List(filter, &ordering, nil)
+		_, err := repo.List(filter, &options)
 		assert.Nil(t, err)
 
 		if err := mock.ExpectationsWereMet(); err != nil {
@@ -86,16 +88,17 @@ func TestListMethod(t *testing.T) {
 		repo.Init(db)
 
 		filter := MyModelFilter{}
-		pagination := Pagination{
+		options := ListOptions{
+			Pagination: &Pagination{
 				Limit: 111,
-			Offset: 0,
+			},
 		}
 
 		sql := "SELECT * FROM my_models LIMIT $1"
 		mock.ExpectQuery(fmt.Sprintf("^%s$", regexp.QuoteMeta(sql))).
-			WithArgs(pagination.Limit)
+			WithArgs(options.Pagination.Limit)
 
-		_, err := repo.List(filter, nil, &pagination)
+		_, err := repo.List(filter, &options)
 		assert.Nil(t, err)
 
 		if err := mock.ExpectationsWereMet(); err != nil {
@@ -111,16 +114,17 @@ func TestListMethod(t *testing.T) {
 		repo.Init(db)
 
 		filter := MyModelFilter{}
-		pagination := Pagination{
+		options := ListOptions{
-			Limit:  0,
+			Pagination: &Pagination{
 				Offset: 222,
+			},
 		}
 
 		sql := "SELECT * FROM my_models OFFSET $1"
 		mock.ExpectQuery(fmt.Sprintf("^%s$", regexp.QuoteMeta(sql))).
-			WithArgs(pagination.Offset)
+			WithArgs(options.Pagination.Offset)
 
-		_, err := repo.List(filter, nil, &pagination)
+		_, err := repo.List(filter, &options)
 		assert.Nil(t, err)
 
 		if err := mock.ExpectationsWereMet(); err != nil {
@@ -136,16 +140,18 @@ func TestListMethod(t *testing.T) {
 		repo.Init(db)
 
 		filter := MyModelFilter{}
-		pagination := Pagination{
+		options := ListOptions{
+			Pagination: &Pagination{
 				Limit:  111,
 				Offset: 222,
+			},
 		}
 
 		sql := "SELECT * FROM my_models LIMIT $1 OFFSET $2"
 		mock.ExpectQuery(fmt.Sprintf("^%s$", regexp.QuoteMeta(sql))).
-			WithArgs(pagination.Limit, pagination.Offset)
+			WithArgs(options.Pagination.Limit, options.Pagination.Offset)
 
-		_, err := repo.List(filter, nil, &pagination)
+		_, err := repo.List(filter, &options)
 		assert.Nil(t, err)
 
 		if err := mock.ExpectationsWereMet(); err != nil {
@@ -169,7 +175,7 @@ func TestListMethod(t *testing.T) {
 		mock.ExpectQuery(fmt.Sprintf("^%s$", regexp.QuoteMeta(sql))).
 			WithArgs(id)
 
-		_, err := repo.List(filter, nil, nil)
+		_, err := repo.List(filter, nil)
 		assert.Nil(t, err)
 
 		if err := mock.ExpectationsWereMet(); err != nil {
@@ -197,7 +203,7 @@ func TestListMethod(t *testing.T) {
 		mock.ExpectQuery(fmt.Sprintf("^%s$", regexp.QuoteMeta(sql))).
 			WithArgs(id, value, count)
 
-		_, err := repo.List(filter, nil, nil)
+		_, err := repo.List(filter, nil)
 		assert.Nil(t, err)
 
 		if err := mock.ExpectationsWereMet(); err != nil {
@@ -220,16 +226,44 @@ func TestListMethod(t *testing.T) {
 			Value: &value,
 			Count: &count,
 		}
-		pagination := Pagination{
+		options := ListOptions{
+			Pagination: &Pagination{
 				Offset: 111,
 				Limit:  222,
+			},
 		}
 
 		sql := "SELECT * FROM my_models WHERE my_models.id = $1 AND my_models.value = $2 AND my_models.count > $3 LIMIT $4 OFFSET $5"
 		mock.ExpectQuery(fmt.Sprintf("^%s$", regexp.QuoteMeta(sql))).
-			WithArgs(id, value, count, pagination.Limit, pagination.Offset)
+			WithArgs(id, value, count, options.Pagination.Limit, options.Pagination.Offset)
 
-		_, err := repo.List(filter, nil, &pagination)
+		_, err := repo.List(filter, &options)
+		assert.Nil(t, err)
+
+		if err := mock.ExpectationsWereMet(); err != nil {
+			t.Errorf("there were unfulfilled expectations: %s", err)
+		}
+	})
+
+	t.Run("Only id and count", func(t *testing.T) {
+		sqldb, db, mock := NewMockDB()
+		defer sqldb.Close()
+
+		repo := RepoBase[MyModel]{}
+		repo.Init(db)
+
+		filter := MyModelFilter{}
+		options := ListOptions{
+			Only: &[]string{
+				"id",
+				"count",
+			},
+		}
+
+		sql := "SELECT id,count FROM my_models"
+		mock.ExpectQuery(fmt.Sprintf("^%s$", regexp.QuoteMeta(sql)))
+
+		_, err := repo.List(filter, &options)
 		assert.Nil(t, err)
 
 		if err := mock.ExpectationsWereMet(); err != nil {