Add endpoint to get allowance history (#37)

Closes #12

Reviewed-on: #37

backend/db.go

@@ -243,7 +243,7 @@ func (db *Db) AddAllowance(userId int, allowance *PostAllowance) error {
 	}
 	defer tx.MustRollback()
 
-	err = tx.Query("insert into history (user_id, date, amount) values (?, ?, ?)").
+	err = tx.Query("insert into history (user_id, timestamp, amount) values (?, ?, ?)").
 		Bind(userId, time.Now().Unix(), allowance.Allowance).
 		Exec()
 	if err != nil {
@@ -251,3 +251,24 @@ func (db *Db) AddAllowance(userId int, allowance *PostAllowance) error {
 	}
 	return tx.Commit()
 }
+
+func (db *Db) GetHistory(userId int) ([]Allowance, error) {
+	history := make([]Allowance, 0)
+	var err error
+
+	for row := range db.db.Query("select amount, `timestamp` from history where user_id = ? order by `timestamp` desc").
+		Bind(userId).Range(&err) {
+		allowance := Allowance{}
+		var timestamp int64
+		err = row.Scan(&allowance.Allowance, &timestamp)
+		if err != nil {
+			return nil, err
+		}
+		allowance.Timestamp = time.Unix(timestamp, 0)
+		history = append(history, allowance)
+	}
+	if err != nil {
+		return nil, err
+	}
+	return history, nil
+}