func listMessages()

in go-gin-react/go-gin-react-part3/main.go [226:276]
31 lines of code
7 McCabe index (conditional complexity)

func listMessages(c *gin.Context, db *sql.DB) {
	// Parse channel ID from URL
	channelID, err := strconv.Atoi(c.Query("channelID"))
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	// Parse optional limit query parameter from URL
	limit, err := strconv.Atoi(c.Query("limit"))
	if err != nil {
		// Set limit to 100 if not provided
		limit = 100
	}

	// Parse last message ID query parameter from URL. This is used to get messages after a certain message.
	lastMessageID, err := strconv.Atoi(c.Query("lastMessageID"))
	if err != nil {
		// Set last message ID to 0 if not provided
		lastMessageID = 0
	}

	// Query database for messages
	rows, err := db.Query("SELECT m.id, channel_id, user_id, u.username AS user_name, message FROM messages m LEFT JOIN users u ON u.id = m.user_id WHERE channel_id = ? AND m.id > ? ORDER BY m.id ASC LIMIT ?", channelID, lastMessageID, limit)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}

	// Create slice of messages
	var messages []Message

	// Iterate over rows
	for rows.Next() {
		// Create new message
		var message Message

		// Scan row into message
		err := rows.Scan(&message.ID, &message.ChannelID, &message.UserID, &message.UserName, &message.Text)
		if err != nil {
			c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
			return
		}

		// Append message to slice
		messages = append(messages, message)
	}

	// Return slice of messages
	c.JSON(http.StatusOK, messages)
}