| 1 | // SPDX-License-Identifier: GPL-3.0-or-later |
| 2 | |
| 3 | package sqlquery |
| 4 | |
| 5 | import ( |
| 6 | "context" |
| 7 | "database/sql" |
| 8 | "time" |
| 9 | ) |
| 10 | |
| 11 | // Queryer is the minimal query interface required by query helpers. |
| 12 | type Queryer interface { |
| 13 | QueryContext(ctx context.Context, query string, args ...any) (*sql.Rows, error) |
| 14 | } |
| 15 | |
| 16 | // AssignFunc receives each row value as string and rowEnd=true for the last column. |
| 17 | type AssignFunc func(column, value string, rowEnd bool) |
| 18 | |
| 19 | // QueryRows executes query and streams row values through assign. |
| 20 | // The returned duration measures query submission latency (QueryContext call). |
| 21 | func QueryRows(ctx context.Context, q Queryer, query string, assign AssignFunc, args ...any) (time.Duration, error) { |
| 22 | start := time.Now() |
| 23 | rows, err := q.QueryContext(ctx, query, args...) |
| 24 | queryDuration := time.Since(start) |
| 25 | if err != nil { |
| 26 | return 0, err |
| 27 | } |
| 28 | defer func() { _ = rows.Close() }() |
| 29 | if err := readRows(rows, assign); err != nil { |
| 30 | return queryDuration, err |
| 31 | } |
| 32 | return queryDuration, nil |
| 33 | } |
| 34 | |
| 35 | // readRows scans all rows and invokes assign for every column value. |
| 36 | func readRows(rows *sql.Rows, assign AssignFunc) error { |
| 37 | if assign == nil { |
| 38 | return nil |
| 39 | } |
| 40 | |
| 41 | columns, err := rows.Columns() |
| 42 | if err != nil { |
| 43 | return err |
| 44 | } |
| 45 | |
| 46 | values := makeValues(len(columns)) |
| 47 | for rows.Next() { |
| 48 | if err := rows.Scan(values...); err != nil { |
| 49 | return err |
| 50 | } |
| 51 | for i := range values { |
| 52 | assign(columns[i], valueToString(values[i]), i == len(values)-1) |
| 53 | } |
| 54 | } |
| 55 | return rows.Err() |
| 56 | } |
| 57 | |
| 58 | func valueToString(value any) string { |
| 59 | v, ok := value.(*sql.NullString) |
| 60 | if !ok || !v.Valid { |
| 61 | return "" |
| 62 | } |
| 63 | return v.String |
| 64 | } |
| 65 | |
| 66 | func makeValues(size int) []any { |
| 67 | vs := make([]any, size) |
| 68 | for i := range vs { |
| 69 | vs[i] = &sql.NullString{} |
| 70 | } |
| 71 | return vs |
| 72 | } |