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config.go
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config.go
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package query
import (
"database/sql"
"fmt"
"strings"
"github.com/pkg/errors"
)
// SelectConfig executes a query statement against a "config" table, which must
// have 'key' and 'value' columns. By default this query returns all keys, but
// additional WHERE filters can be specified.
//
// Returns a map of key names to their associated values.
func SelectConfig(tx *sql.Tx, table string, where string, args ...interface{}) (map[string]string, error) {
query := fmt.Sprintf("SELECT key, value FROM %s", table)
if where != "" {
query += fmt.Sprintf(" WHERE %s", where)
}
rows, err := tx.Query(query, args...)
if err != nil {
return nil, err
}
defer rows.Close()
values := map[string]string{}
for rows.Next() {
var key string
var value string
err := rows.Scan(&key, &value)
if err != nil {
return nil, err
}
values[key] = value
}
err = rows.Err()
if err != nil {
return nil, err
}
return values, nil
}
// UpdateConfig updates the given keys in the given table. Config keys set to
// empty values will be deleted.
func UpdateConfig(tx *sql.Tx, table string, values map[string]string) error {
changes := map[string]string{}
deletes := []string{}
for key, value := range values {
if value == "" {
deletes = append(deletes, key)
continue
}
changes[key] = value
}
err := upsertConfig(tx, table, changes)
if err != nil {
return errors.Wrap(err, "updating values failed")
}
err = deleteConfig(tx, table, deletes)
if err != nil {
return errors.Wrap(err, "deleting values failed")
}
return nil
}
// Insert or updates the key/value rows of the given config table.
func upsertConfig(tx *sql.Tx, table string, values map[string]string) error {
if len(values) == 0 {
return nil // Nothing to update
}
query := fmt.Sprintf("INSERT OR REPLACE INTO %s (key, value) VALUES", table)
exprs := []string{}
params := []interface{}{}
for key, value := range values {
exprs = append(exprs, "(?, ?)")
params = append(params, key)
params = append(params, value)
}
query += strings.Join(exprs, ",")
_, err := tx.Exec(query, params...)
return err
}
// Delete the given key rows from the given config table.
func deleteConfig(tx *sql.Tx, table string, keys []string) error {
n := len(keys)
if n == 0 {
return nil // Nothing to delete.
}
query := fmt.Sprintf("DELETE FROM %s WHERE key IN %s", table, Params(n))
values := make([]interface{}, n)
for i, key := range keys {
values[i] = key
}
_, err := tx.Exec(query, values...)
return err
}