Fix panic (#18)

* reproduce panice when calling get one in transaction

* pass scan.API while creating tx Querier

pgkit.go

@@ -21,7 +21,7 @@ type DB struct {
 }
 
 func (d *DB) TxQuery(tx pgx.Tx) *Querier {
-	return &Querier{tx: tx, SQL: d.SQL, pool: d.Conn}
+	return &Querier{tx: tx, SQL: d.SQL, pool: d.Conn, Scan: d.Query.Scan}
 }
 
 type Config struct {

tests/pgkit_test.go

@@ -134,6 +134,23 @@ func TestSugarInsertAndSelectRecords(t *testing.T) {
 	assert.Equal(t, "joe", accounts[0].Name)
 }
 
+func TestGetOneInTransaction(t *testing.T) {
+	ctx := context.Background()
+	q2 := DB.SQL.Select("*").From("accounts")
+
+	var account Account
+	tx, err := DB.Conn.BeginTx(ctx, pgx.TxOptions{})
+	assert.NoError(t, err)
+
+	defer tx.Rollback(ctx)
+
+	err = DB.TxQuery(tx).GetOne(ctx, q2, &account)
+	assert.NoError(t, err)
+
+	err = tx.Commit(ctx)
+	assert.NoError(t, err)
+}
+
 func TestSugarInsertAndSelectRecordsReturningID(t *testing.T) {
 	truncateTable(t, "accounts")