Deleting questions and adding tests for deleteing

server/services/poll.go

@@ -12,6 +12,7 @@ import (
 var ErrQuestionAlreadyExists = errors.New("Question already exists")
 var ErrQuestionDoesntExist = errors.New("Question does not exist yet")
 var ErrVoterAlreadyVoted = errors.New("Voter already voted")
+var ErrPollNotFound = errors.New("Poll not found")
 
 func CreatePoll(poll *models.Poll) (*models.Poll, error) {
 	new_poll := models.Poll{}
@@ -100,7 +101,7 @@ func GetPollByQuestion(question string) (*models.Poll, error) {
 	)
 
 	if err == sql.ErrNoRows {
-		return nil, ErrQuestionDoesntExist
+		return nil, ErrPollNotFound
 	} else if err != nil {
 		return nil, err
 	}
@@ -132,7 +133,7 @@ func GetPollByQuestion(question string) (*models.Poll, error) {
 func GetAndCreatePollByQuestion(question string) (*models.Poll, error) {
 	new_poll, err := GetPollByQuestion(question)
 
-	if err == ErrQuestionDoesntExist {
+	if err == ErrPollNotFound {
 		create_poll := &models.Poll{
 			Question: question,
 			ExpiresAt: time.Now().Add(time.Hour * 10).Format("2006-01-02 15:04:05"),
@@ -233,5 +234,54 @@ func SetVote(vote *models.Vote) error {
 		return err
 	}
 
+	return nil
+}
+
+// Delete a poll by name
+func DeletePollByQuestion(question string) error {
+	db_conn, err := db.Connect()
+	if err != nil {
+		return err
+	}
+	defer db.Close()
+
+	delete_votes_stmt, err := db_conn.Prepare(`
+		DELETE FROM voters
+		WHERE poll_id IN (
+			SELECT id 
+			FROM polls 
+			WHERE question == $1
+		)
+	`)
+	if err != nil {
+		return err
+	}
+	defer delete_votes_stmt.Close()
+
+	_, err = delete_votes_stmt.Exec(question)
+	if err != nil {
+		return err
+	}
+
+	delete_poll_stmt, err := db_conn.Prepare(`
+		DELETE FROM polls
+		WHERE question == $1
+	`)
+	if err != nil {
+		return err
+	}
+	defer delete_poll_stmt.Close()
+
+	res, err := delete_poll_stmt.Exec(question)
+	if err != nil {
+		return err
+	}
+
+	if num, err := res.RowsAffected(); num != 1 {
+		return errors.New("Failed to delete poll")
+	} else if err != nil {
+		return err
+	}
+
 	return nil
 }