module pg #flag -lpq #flag linux -I/usr/include/postgresql #flag darwin -I/opt/local/include/postgresql11 #include struct DB { mut: conn &C.PGconn } struct Row { pub mut: vals []string } struct C.PGResult { } struct Config { pub: host string user string password string dbname string } fn C.PQconnectdb(a byteptr) &C.PGconn fn C.PQerrorMessage(voidptr) byteptr fn C.PQgetvalue(voidptr, int, int) byteptr fn C.PQstatus(voidptr) int pub fn connect(config pg.Config) DB { conninfo := 'host=$config.host user=$config.user dbname=$config.dbname' conn:=C.PQconnectdb(conninfo.str) status := C.PQstatus(conn) if status != C.CONNECTION_OK { error_msg := C.PQerrorMessage(conn) eprintln('Connection to a PG database failed: ' + string(error_msg)) exit(1) } return DB {conn: conn} } fn res_to_rows(res voidptr) []pg.Row { nr_rows := C.PQntuples(res) nr_cols := C.PQnfields(res) mut rows := []pg.Row for i := 0; i < nr_rows; i++ { mut row := Row{} for j := 0; j < nr_cols; j++ { val := C.PQgetvalue(res, i, j) row.vals << string(val) } rows << row } return rows } pub fn (db DB) q_int(query string) int { rows := db.exec(query) if rows.len == 0 { println('q_int "$query" not found') return 0 } row := rows[0] if row.vals.len == 0 { return 0 } val := row.vals[0] return val.int() } pub fn (db DB) q_string(query string) string { rows := db.exec(query) if rows.len == 0 { println('q_string "$query" not found') return '' } row := rows[0] if row.vals.len == 0 { return '' } val := row.vals[0] return val } pub fn (db DB) q_strings(query string) []pg.Row { return db.exec(query) } pub fn (db DB) exec(query string) []pg.Row { res := C.PQexec(db.conn, query.str) e := string(C.PQerrorMessage(db.conn)) if e != '' { println('pg exec error:') println(e) return res_to_rows(res) } return res_to_rows(res) } fn rows_first_or_empty(rows []pg.Row) ?pg.Row { if rows.len == 0 { return error('no row') } return rows[0] } pub fn (db DB) exec_one(query string) ?pg.Row { res := C.PQexec(db.conn, query.str) e := string(C.PQerrorMessage(db.conn)) if e != '' { return error('pg exec error: "$e"') } row := rows_first_or_empty( res_to_rows(res) ) return row } // pub fn (db DB) exec_param2(query string, param, param2 string) []pg.Row { mut param_vals := [2]byteptr param_vals[0] = param.str param_vals[1] = param2.str res := C.PQexecParams(db.conn, query.str, 2, 0, param_vals, 0, 0, 0) e := string(C.PQerrorMessage(db.conn)) if e != '' { println('pg exec2 error:') println(e) return res_to_rows(res) } return res_to_rows(res) } pub fn (db DB) exec_param(query string, param string) []pg.Row { mut param_vals := [1]byteptr param_vals[0] = param.str res := C.PQexecParams(db.conn, query.str, 1, 0, param_vals, 0, 0, 0) return res_to_rows(res) }