ax/db/rel.go

package db

import "axolotl/models"

func (db *DB) AddRel(f, t string, r models.RelType) error {
	_, err := db.Exec("INSERT OR IGNORE INTO rels (from_id, to_id, rel_type) VALUES (?, ?, ?)", f, t, r)
	return err
}
func (db *DB) RemoveRel(f, t string, r models.RelType) error {
	_, err := db.Exec("DELETE FROM rels WHERE from_id = ? AND to_id = ? AND rel_type = ?", f, t, r)
	return err
}

func getIDs(db *DB, q, id string, r models.RelType) ([]string, error) {
	rows, err := db.Query(q, id, r)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var ids []string
	for rows.Next() {
		var i string
		rows.Scan(&i)
		ids = append(ids, i)
	}
	return ids, nil
}

func (db *DB) GetRelated(id string, r models.RelType) ([]string, error) {
	return getIDs(db, "SELECT to_id FROM rels WHERE from_id = ? AND rel_type = ?", id, r)
}
func (db *DB) GetIncomingRels(id string, r models.RelType) ([]string, error) {
	return getIDs(db, "SELECT from_id FROM rels WHERE to_id = ? AND rel_type = ?", id, r)
}

func (db *DB) GetRelNames(n *models.Node, r models.RelType) ([]string, error) {
	ids := n.Relations[string(r)]
	if len(ids) == 0 {
		return nil, nil
	}
	result := make([]string, 0, len(ids))
	for _, id := range ids {
		var title string
		if err := db.QueryRow("SELECT title FROM nodes WHERE id = ?", id).Scan(&title); err != nil {
			return nil, err
		}
		result = append(result, title)
	}
	return result, nil
}