module pg #flag -lpq #flag linux -I/usr/include/postgresql #flag darwin -I/opt/local/include/postgresql11 #include pub struct DB { mut: conn &C.PGconn } pub struct Row { pub mut: vals []string } struct C.PGResult { } pub struct Config { pub: host string port int = 5432 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 fn C.PQntuples(voidptr) int fn C.PQnfields(voidptr) int fn C.PQexec(voidptr) voidptr fn C.PQexecParams(voidptr) voidptr pub fn connect(config Config) ?DB { conninfo := 'host=$config.host port=$config.port user=$config.user dbname=$config.dbname password=$config.password' conn := C.PQconnectdb(conninfo.str) status := C.PQstatus(conn) println("status=$status") if status != C.CONNECTION_OK { error_msg := C.PQerrorMessage(conn) return error ('Connection to a PG database failed: ' + string(error_msg)) } return DB {conn: conn} } fn res_to_rows(res voidptr) []Row { nr_rows := C.PQntuples(res) nr_cols := C.PQnfields(res) mut rows := []Row for i in 0..nr_rows { mut row := Row{} for j in 0..nr_cols { 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) []Row { return db.exec(query) } pub fn (db DB) exec(query string) []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 []Row) ?Row { if rows.len == 0 { return error('no row') } return rows[0] } pub fn (db DB) exec_one(query string) ?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 } // The entire function can be considered unsafe because of the malloc and the // free. This prevents warnings and doesn't seem to affect behavior. pub fn (db DB) exec_param_many(query string, params []string) []Row { unsafe { mut param_vals := &byteptr( malloc( params.len * sizeof(byteptr) ) ) for i in 0..params.len { param_vals[i] = params[i].str } res := C.PQexecParams(db.conn, query.str, params.len, 0, param_vals, 0, 0, 0) free(param_vals) return db.handle_error_or_result(res, 'exec_param_many') } } pub fn (db DB) exec_param2(query string, param, param2 string) []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) return db.handle_error_or_result(res, 'exec_param2') } pub fn (db DB) exec_param(query string, param string) []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 db.handle_error_or_result(res, 'exec_param') } fn (db DB) handle_error_or_result(res voidptr, elabel string) []Row { e := string(C.PQerrorMessage(db.conn)) if e != '' { println('pg $elabel error:') println(e) return res_to_rows(res) } return res_to_rows(res) }