Implement get goals (#25)

Closes #13

Reviewed-on: #25

backend/db.go

@@ -57,3 +57,32 @@ func (db *Db) GetUser(id int) (*User, error) {
 	}
 	return user, nil
 }
+
+func (db *Db) UserExists(userId int) (bool, error) {
+	count := 0
+	err := db.db.Query("select count(*) from users where id = ?").
+		Bind(userId).ScanSingle(&count)
+	if err != nil {
+		return false, err
+	}
+	return count > 0, nil
+}
+
+func (db *Db) GetUserGoals(userId int) ([]Goal, error) {
+	goals := make([]Goal, 0)
+	var err error
+
+	for row := range db.db.Query("select id, name, target, progress, weight from goals where user_id = ?").
+		Bind(userId).Range(&err) {
+		goal := Goal{}
+		err = row.Scan(&goal.ID, &goal.Name, &goal.Target, &goal.Progress, &goal.Weight)
+		if err != nil {
+			return nil, err
+		}
+		goals = append(goals, goal)
+	}
+	if err != nil {
+		return nil, err
+	}
+	return goals, nil
+}