Mini Project: Task Manager (Part 1) - Struct & Slice

Let's think about this for a second

In this project we'll combine the concepts you learned in the Basics chapters - struct, slice, function, loop - into a single application. Task Manager is a program that keeps track of a task list right in the terminal, with commands like Add, List, Complete, and Remove. In this Part 1, we'll design the core data structure, the Task struct, and build a list that stores tasks in a slice. In Part 2 and Part 3 we'll keep adding features and gradually build the project out to completion. The main thing to take away from this stage is how a real-world app starts out with its data model.

Let's build it for real

Define a Task struct with ID (int), Title (string), and Done (bool) fields. Inside main(), declare a slice variable called tasks []Task. Write an addTask(tasks []Task, title string) []Task function that appends a new Task and returns the updated slice. Write a listTasks(tasks []Task) function that uses a for range loop to print out the task list along with each item's index, title, and done status. Show the done status using [ ] and [x] formatting.

Defined the Task struct with the three fields ID, Title, and Done
addTask function appends to the slice and returns it correctly
listTasks function prints the task list with formatted output

Code Example

package main

import "fmt"

type Task struct {
	ID    int
	Title string
	Done  bool
}

func addTask(tasks []Task, title string) []Task {
	newTask := Task{
		ID:    len(tasks) + 1,
		Title: title,
		Done:  false,
	}
	return append(tasks, newTask)
}

func listTasks(tasks []Task) {
	if len(tasks) == 0 {
		fmt.Println("Task list is empty.")
		return
	}
	for _, t := range tasks {
		status := "[ ]"
		if t.Done {
			status = "[x]"
		}
		fmt.Printf("%s %d. %s\n", status, t.ID, t.Title)
	}
}

func main() {
	var tasks []Task
	tasks = addTask(tasks, "Learn Go basics")
	tasks = addTask(tasks, "Build task manager")
	tasks = addTask(tasks, "Write tests")

	listTasks(tasks)
}

You should see

The terminal will print the 3 tasks as a numbered list, each with a [ ] status marker.

Try it in 5 minutes

Within 5 minutes, call addTask to add up to 5 tasks, then manually set the Done field to true for one task and see how the listTasks output changes.

One quick word of caution

When you pass a slice into a function, append may or may not touch the original slice depending on capacity - so always save the slice the function returns rather than assuming the original got updated.