improve KeysetPagination readability by using firstId and lastId

Signed-off-by: Hayim Shaul <[email protected]>

Author: Hayim Shaul

platform/common/driver/vault.go

@@ -78,12 +78,12 @@ func (q *SqlQuery) SetTable(t string) {
 	q.table = t
 }
 
-func (q *SqlQuery) SetLimit(l string) {
-	q.limit = l
+func (q *SqlQuery) SetLimit(l int) {
+	q.limit = fmt.Sprintf("%d", l)
 }
 
-func (q *SqlQuery) SetOffset(o string) {
-	q.offset = o
+func (q *SqlQuery) SetOffset(o int) {
+	q.offset = fmt.Sprintf("%d", o)
 }
 
 func (q *SqlQuery) SetOrder(o string) {

platform/view/services/db/driver/sql/common/pagination.go

@@ -94,9 +94,9 @@ type KeysetPagination struct {
 	sqlIdName string
 	// name of the field in the struct that is returned from the database
 	idFieldName string
-	// the last id value read and the offset in which it was read
-	lastId     string // TODO: should this be int?
-	lastOffset int
+	// the first and last id values in the page
+	firstId string
+	lastId  string
 }
 
 func NewKeysetPagination(offset int, pageSize int, sqlIdName string, idFieldName string) (*KeysetPagination, error) {
@@ -111,23 +111,34 @@ func NewKeysetPagination(offset int, pageSize int, sqlIdName string, idFieldName
 		pageSize:    pageSize,
 		sqlIdName:   sqlIdName,
 		idFieldName: idFieldName,
+		firstId:     "",
 		lastId:      "",
-		lastOffset:  -1,
 	}, nil
 }
 
 func (p *KeysetPagination) GoToOffset(offset int) (driver.Pagination, error) {
 	if offset < 0 {
 		return NewEmptyPagination(), nil
 	}
-	return &KeysetPagination{
-		offset:      offset,
-		pageSize:    p.pageSize,
-		sqlIdName:   p.sqlIdName,
-		idFieldName: p.idFieldName,
-		lastId:      p.lastId,
-		lastOffset:  p.lastOffset,
-	}, nil
+	if offset == p.offset+p.pageSize {
+		return &KeysetPagination{
+			offset:      offset,
+			pageSize:    p.pageSize,
+			sqlIdName:   p.sqlIdName,
+			idFieldName: p.idFieldName,
+			firstId:     p.lastId,
+			lastId:      "",
+		}, nil
+	} else {
+		return &KeysetPagination{
+			offset:      offset,
+			pageSize:    p.pageSize,
+			sqlIdName:   p.sqlIdName,
+			idFieldName: p.idFieldName,
+			firstId:     "",
+			lastId:      "",
+		}, nil
+	}
 }
 
 func (p *KeysetPagination) GoToPage(pageNum int) (driver.Pagination, error) {
@@ -146,7 +157,6 @@ func (p *KeysetPagination) Prev() (driver.Pagination, error) { return p.GoBack(1
 func (p *KeysetPagination) Next() (driver.Pagination, error) { return p.GoForward(1) }
 func (p *KeysetPagination) UpdateId(id string) {
 	p.lastId = id
-	p.lastOffset = p.offset
 }
 
 func NewPaginationInterpreter() *paginationInterpreter {
@@ -164,22 +174,22 @@ func (i *paginationInterpreter) Interpret(p driver.Pagination, sql driver.SqlQue
 	case *NoPagination:
 		return sql, nil
 	case *OffsetPagination:
-		sql.SetLimit(fmt.Sprintf("%d", pagination.pageSize))
-		sql.SetOffset(fmt.Sprintf("%d", pagination.offset))
+		sql.SetLimit(pagination.pageSize)
+		sql.SetOffset(pagination.offset)
 		return sql, nil
 	case *KeysetPagination:
 		sql.SetOrder(fmt.Sprintf("%s ASC", pagination.sqlIdName))
-		sql.SetLimit(fmt.Sprintf("%d", pagination.pageSize))
-		if (pagination.lastOffset != -1) && (pagination.offset == pagination.lastOffset+pagination.pageSize) {
-			lastId := sql.AddParam(pagination.lastId)
+		sql.SetLimit(pagination.pageSize)
+		if pagination.firstId != "" {
+			lastId := sql.AddParam(pagination.firstId)
 			sql.AddWhere(fmt.Sprintf("%s>$%d", pagination.sqlIdName, lastId))
 		} else {
-			sql.SetOffset(fmt.Sprintf("%d", pagination.offset))
+			sql.SetOffset(pagination.offset)
 		}
 		return sql, nil
 	case *EmptyPagination:
-		sql.SetLimit("0")
-		sql.SetOffset("0")
+		sql.SetLimit(0)
+		sql.SetOffset(0)
 		return sql, nil
 	default:
 		return sql, errors.Errorf("invalid pagination option %+v", pagination)
@@ -196,21 +206,21 @@ func NewPaginationUpdater[R comparable]() *paginationUpdater[R] {
 	return &paginationUpdater[R]{}
 }
 
-func (i *paginationUpdater[R]) Update(recs *driver.PageIterator[*R]) (*driver.PageIterator[*R], error) {
+func (i *paginationUpdater[R]) Update(recs driver.PageIterator[*R]) (driver.PageIterator[*R], error) {
 	switch page := recs.Pagination.(type) {
 	case *KeysetPagination:
 		items := recs.Items
 		record, newIt, err := collections.ReadLast(items)
 		if err != nil {
-			return nil, err
+			return recs, err
 		}
 		if record != nil {
 			refRec := reflect.ValueOf(*record)
 			id := refRec.FieldByName(page.idFieldName)
 			page.UpdateId(id.String())
 		}
-		return (&driver.PageIterator[*R]{Items: newIt, Pagination: page}), nil
+		return (driver.PageIterator[*R]{Items: newIt, Pagination: page}), nil
 	default:
-		return (&driver.PageIterator[*R]{Items: recs.Items, Pagination: recs.Pagination}), nil
+		return (driver.PageIterator[*R]{Items: recs.Items, Pagination: recs.Pagination}), nil
 	}
 }

platform/view/services/db/driver/sql/common/vault.go

@@ -483,9 +483,9 @@ func (db *vaultReader) GetAllTxStatuses(ctx context.Context, sql driver.SqlQuery
 		return nil, err
 	}
 	pu := NewPaginationUpdater[driver.TxStatus]()
-	pageIt := &driver.PageIterator[*driver.TxStatus]{Items: txStatusIterator, Pagination: pagination}
+	pageIt := driver.PageIterator[*driver.TxStatus]{Items: txStatusIterator, Pagination: pagination}
 	pageIt, err = pu.Update(pageIt)
-	return pageIt, err
+	return &pageIt, err
 }
 
 func (db *vaultReader) queryStatus(where string, params []any, limit string) (driver.TxStatusIterator, error) {