| 1 | // SPDX-License-Identifier: GPL-3.0-or-later |
| 2 | |
| 3 | package sqlquery |
| 4 | |
| 5 | import ( |
| 6 | "context" |
| 7 | "fmt" |
| 8 | ) |
| 9 | |
| 10 | type PlaceholderStyle int |
| 11 | |
| 12 | const ( |
| 13 | PlaceholderQuestion PlaceholderStyle = iota |
| 14 | PlaceholderDollar |
| 15 | ) |
| 16 | |
| 17 | func tableColumnsQuery(style PlaceholderStyle) (string, error) { |
| 18 | switch style { |
| 19 | case PlaceholderQuestion: |
| 20 | return ` |
| 21 | SELECT COLUMN_NAME |
| 22 | FROM information_schema.COLUMNS |
| 23 | WHERE TABLE_SCHEMA = ? |
| 24 | AND TABLE_NAME = ?`, nil |
| 25 | case PlaceholderDollar: |
| 26 | return ` |
| 27 | SELECT COLUMN_NAME |
| 28 | FROM information_schema.COLUMNS |
| 29 | WHERE TABLE_SCHEMA = $1 |
| 30 | AND TABLE_NAME = $2`, nil |
| 31 | default: |
| 32 | return "", fmt.Errorf("unsupported placeholder style: %d", style) |
| 33 | } |
| 34 | } |
| 35 | |
| 36 | // FetchTableColumns returns the set of column names for schema.table. |
| 37 | // If transform is non-nil, it is applied to each column name before insertion. |
| 38 | func FetchTableColumns(ctx context.Context, q Queryer, schema, table string, style PlaceholderStyle, transform func(string) string) (map[string]bool, error) { |
| 39 | query, err := tableColumnsQuery(style) |
| 40 | if err != nil { |
| 41 | return nil, err |
| 42 | } |
| 43 | rows, err := q.QueryContext(ctx, query, schema, table) |
| 44 | if err != nil { |
| 45 | return nil, err |
| 46 | } |
| 47 | defer func() { _ = rows.Close() }() |
| 48 | |
| 49 | cols := make(map[string]bool) |
| 50 | for rows.Next() { |
| 51 | var name string |
| 52 | if err := rows.Scan(&name); err != nil { |
| 53 | return nil, err |
| 54 | } |
| 55 | if transform != nil { |
| 56 | name = transform(name) |
| 57 | } |
| 58 | cols[name] = true |
| 59 | } |
| 60 | if err := rows.Err(); err != nil { |
| 61 | return nil, err |
| 62 | } |
| 63 | return cols, nil |
| 64 | } |