Rework query to return lists

guildService.go

@@ -12,20 +12,30 @@ type GuildServiceQuery struct {
 	ID   *int64  `db:"id"`
 }
 
-func (gs *GuildService) Query(query GuildServiceQuery) (Guild, error) {
-	guild := Guild{}
+func (gs *GuildService) Query(query GuildServiceQuery) ([]Guild, error) {
+	res := []Guild{}
 	sqlQuery := "SELECT id, name FROM guild"
 	whereQuery := BuildWhereQuery(query)
 	if whereQuery != "" {
 		sqlQuery += " " + whereQuery
 	}
 
-	err := gs.db.readConn.QueryRow(sqlQuery).Scan(&guild.ID, &guild.Name)
+	rows, err := gs.db.readConn.Query(sqlQuery)
 	if err != nil {
-		return guild, fmt.Errorf("failed getting guild for query %q: %v", sqlQuery, err)
+		return res, fmt.Errorf("failed getting guilds for query %q: %v", sqlQuery, err)
+	}
+	defer rows.Close()
+
+	for rows.Next() {
+		guild := Guild{}
+		err := rows.Scan(&guild.ID, &guild.Name)
+		if err != nil {
+			return res, fmt.Errorf("failed scanning guild: %v", err)
+		}
+		res = append(res, guild)
 	}
 
-	return guild, nil
+	return res, nil
 }
 
 func (gs *GuildService) Create(name string) (Guild, error) {
@@ -40,13 +50,24 @@ func (gs *GuildService) Create(name string) (Guild, error) {
 		return guild, fmt.Errorf("failed to get last insert id: %v", err)
 	}
 
-	return gs.Query(GuildServiceQuery{ID: &id})
+	qres, err := gs.Query(GuildServiceQuery{ID: &id})
+	if err != nil {
+		return guild, fmt.Errorf("failed getting guild for id %d: %v", id, err)
+	}
+	if len(qres) > 1 {
+		return guild, fmt.Errorf("more than one guild found for id %d", id)
+	}
+
+	return qres[0], nil
 }
 
 func (gs *GuildService) GetOrCreate(name string) (Guild, error) {
 	guild := Guild{}
-	guild, err := gs.Query(GuildServiceQuery{Name: &name})
+	guilds, err := gs.Query(GuildServiceQuery{Name: &name})
 	if err != nil {
+		if len(guilds) > 1 {
+			return guild, fmt.Errorf("more than one guild found for name %s", name)
+		}
 		guild, err = gs.Create(name)
 		if err != nil {
 			return guild, fmt.Errorf("failed creating guild: %v", err)