Use dedicated type for each order field

Signed-off-by: gearnode <bryan@frimin.fr>

pkg/page/cursor.go

@@ -19,17 +19,17 @@ import (
 )
 
 type (
-	Cursor struct {
+	Cursor[T OrderField] struct {
 		Size     int
 		Position Position
 		Key      *CursorKey
-		OrderBy  OrderBy
+		OrderBy  OrderBy[T]
 	}
 
 	Position string
 
-	OrderBy struct {
-		Field     OrderField
+	OrderBy[T OrderField] struct {
+		Field     T
 		Direction OrderDirection
 	}
 )
@@ -41,27 +41,20 @@ const (
 	Head Position = "HEAD"
 )
 
-func NewCursor(size int, from *CursorKey, pos Position, orderBy *OrderBy) *Cursor {
+func NewCursor[T OrderField](size int, from *CursorKey, pos Position, orderBy OrderBy[T]) *Cursor[T] {
 	if size == 0 {
 		size = DefaultCursorSize
 	}
 
-	if orderBy == nil {
-		orderBy = &OrderBy{
-			Field:     OrderFieldCreatedAt,
-			Direction: OrderDirectionDesc,
-		}
-	}
-
-	return &Cursor{
+	return &Cursor[T]{
 		Size:     size,
 		Key:      from,
 		Position: pos,
-		OrderBy:  *orderBy,
+		OrderBy:  orderBy,
 	}
 }
 
-func (c *Cursor) SQLFragment() string {
+func (c *Cursor[T]) SQLFragment() string {
 	fieldName := c.OrderBy.Field.Column()
 
 	var orderDirection string
@@ -88,7 +81,7 @@ func (c *Cursor) SQLFragment() string {
 	return whereClause + " ORDER BY " + orderByClause + " LIMIT @cursor_limit"
 }
 
-func (c *Cursor) SQLArguments() pgx.NamedArgs {
+func (c *Cursor[T]) SQLArguments() pgx.NamedArgs {
 	var size = c.Size
 	if c.Key == nil {
 		size += 1

pkg/page/order_field.go

@@ -21,51 +21,6 @@ import (
 type (
 	OrderField interface {
 		Column() string
+		fmt.Stringer
 	}
-
-	GenericOrderField string
 )
-
-const (
-	OrderFieldCreatedAt GenericOrderField = "CREATED_AT"
-	OrderFieldUpdatedAt GenericOrderField = "UPDATED_AT"
-	OrderFieldName      GenericOrderField = "NAME"
-)
-
-func (of GenericOrderField) String() string {
-	return string(of)
-}
-
-func (of GenericOrderField) Column() string {
-	switch of {
-	case OrderFieldCreatedAt:
-		return "created_at"
-	case OrderFieldUpdatedAt:
-		return "updated_at"
-	case OrderFieldName:
-		return "name"
-	default:
-		return ""
-	}
-}
-
-func (of GenericOrderField) MarshalText() ([]byte, error) {
-	return []byte(of.String()), nil
-}
-
-func (of *GenericOrderField) UnmarshalText(data []byte) error {
-	val := string(data)
-
-	switch val {
-	case OrderFieldCreatedAt.String():
-		*of = OrderFieldCreatedAt
-	case OrderFieldUpdatedAt.String():
-		*of = OrderFieldUpdatedAt
-	case OrderFieldName.String():
-		*of = OrderFieldName
-	default:
-		return fmt.Errorf("invalid GenericOrderField value: %q", val)
-	}
-
-	return nil
-}

pkg/page/page.go

@@ -15,8 +15,8 @@
 package page
 
 type (
-	Paginable interface {
-		CursorKey(orderBy OrderField) CursorKey
+	Paginable[T OrderField] interface {
+		CursorKey(orderBy T) CursorKey
 	}
 
 	PageInfo struct {
@@ -24,14 +24,14 @@ type (
 		HasPrev bool
 	}
 
-	Page[T Paginable] struct {
+	Page[T Paginable[U], U OrderField] struct {
 		Info   *PageInfo
-		Cursor *Cursor
+		Cursor *Cursor[U]
 		Data   []T
 	}
 )
 
-func (p *Page[T]) First() T {
+func (p *Page[T, U]) First() T {
 	if len(p.Data) == 0 {
 		var zero T
 		return zero
@@ -40,7 +40,7 @@ func (p *Page[T]) First() T {
 	return p.Data[0]
 }
 
-func (p *Page[T]) Last() T {
+func (p *Page[T, U]) Last() T {
 	if len(p.Data) == 0 {
 		var zero T
 		return zero
@@ -49,11 +49,11 @@ func (p *Page[T]) Last() T {
 	return p.Data[len(p.Data)-1]
 }
 
-func NewPage[T Paginable](data []T, c *Cursor) *Page[T] {
+func NewPage[T Paginable[U], U OrderField](data []T, c *Cursor[U]) *Page[T, U] {
 	pi := &PageInfo{}
 
 	if len(data) == 0 {
-		return &Page[T]{
+		return &Page[T, U]{
 			Info: pi,
 			Data: data,
 		}
@@ -109,7 +109,7 @@ func NewPage[T Paginable](data []T, c *Cursor) *Page[T] {
 		}
 	}
 
-	return &Page[T]{
+	return &Page[T, U]{
 		Info:   pi,
 		Cursor: c,
 		Data:   edges,