Add a functional iterator over query rows.

1 files changed, 35 insertions, 0 deletions

diff --git a/sqlr.go b/sqlr.go
index 4ac798f..9e4ba38 100644
--- a/sqlr.go
+++ b/sqlr.go
@@ -3,8 +3,10 @@
 package sqlr
 
 import (
+	"context"
 	"database/sql"
 	"fmt"
+	"iter"
 	"reflect"
 )
 
@@ -42,3 +44,36 @@ Cols:
 
 	return rows.Scan(dest...)
 }
+
+// Querier is the underlying type used to query the database,
+// usually *sql.DB or *sql.Tx.
+type Querier interface {
+	QueryContext(context.Context, string, ...any) (*sql.Rows, error)
+}
+
+// Query returns an iterator over the rows matched by a query.
+func Query[Row any](ctx context.Context, querier Querier, query string, args ...any) iter.Seq2[Row, error] {
+	return func(yield func(Row, error) bool) {
+		rows, err := querier.QueryContext(ctx, query, args...)
+		if err != nil {
+			var zero Row
+			yield(zero, err)
+			return
+		}
+		defer rows.Close()
+		for rows.Next() {
+			var row Row
+			if err := Scan(rows, &row); err != nil {
+				yield(row, err)
+				return
+			}
+			if !yield(row, nil) {
+				return
+			}
+		}
+		if err := rows.Err(); err != nil {
+			var zero Row
+			yield(zero, err)
+		}
+	}
+}