Building a Todo List Web Application in Go

Introduction
Prerequisites
Setup
Creating the Web Application
Adding Functionality
Conclusion

Introduction

In this tutorial, we will build a Todo List web application using the Go programming language. By the end of this tutorial, you will have a functioning web application where users can create, update, and delete todo items. We will cover the basics of web programming in Go, including routing, handling requests and responses, and storing data.

Prerequisites

To follow along with this tutorial, you should have a basic understanding of the Go programming language. It will be helpful to have Go installed locally on your machine. Additionally, you should have a text editor and a web browser.

Setup

Before we start building the web application, let’s set up our development environment. Follow these steps:

Install Go by downloading the latest stable release from the official Go website (https://golang.org/dl/).
Set up a new Go module for our project by running the following command in your terminal:
```
 go mod init todoapp
```
Create a new directory for our web application and navigate into it:
```
 mkdir todoapp && cd todoapp
```
Open your text editor and create a new file called main.go.

With the setup complete, we can now start building our Todo List web application.

Creating the Web Application

Open the main.go file in your text editor and import the necessary packages:

 package main
    
 import (
 	"net/http"
    
 	"github.com/gorilla/mux"
 )

Define the main function and create a new router using the Gorilla Mux package:
```
 func main() {
 	r := mux.NewRouter()
 }
```

Set up the routing for our web application. We will create a separate handler function for each route:

 func main() {
 	r := mux.NewRouter()
    
 	r.HandleFunc("/", homeHandler).Methods("GET")
 	r.HandleFunc("/todos", listTodosHandler).Methods("GET")
 	r.HandleFunc("/todos", createTodoHandler).Methods("POST")
 	r.HandleFunc("/todos/{id}", getTodoHandler).Methods("GET")
 	r.HandleFunc("/todos/{id}", updateTodoHandler).Methods("PUT")
 	r.HandleFunc("/todos/{id}", deleteTodoHandler).Methods("DELETE")
    
 	http.ListenAndServe(":8080", r)
 }

Implement the handler functions for each route:

 func homeHandler(w http.ResponseWriter, r *http.Request) {
 	w.Write([]byte("Welcome to the Todo List web application!"))
 }
    
 func listTodosHandler(w http.ResponseWriter, r *http.Request) {
 	// Implement logic to fetch and display all todos from the database
 }
    
 func createTodoHandler(w http.ResponseWriter, r *http.Request) {
 	// Implement logic to create a new todo and store it in the database
 }
    
 func getTodoHandler(w http.ResponseWriter, r *http.Request) {
 	// Implement logic to fetch and display a specific todo from the database
 }
    
 func updateTodoHandler(w http.ResponseWriter, r *http.Request) {
 	// Implement logic to update a specific todo in the database
 }
    
 func deleteTodoHandler(w http.ResponseWriter, r *http.Request) {
 	// Implement logic to delete a specific todo from the database
 }

Start the web server by running the following command in your terminal:
```
 go run main.go
```
Open your web browser and visit http://localhost:8080 to see the home page of your Todo List web application.

Congratulations! You have created the basic structure of your Todo List web application.

Adding Functionality

Now that we have the foundation of our web application, let’s add some functionality to it.

Create a Todo struct that represents a todo item:

 type Todo struct {
 	ID    string
 	Title string
 }

Implement the logic to fetch all todos from the database in the listTodosHandler function:

 func listTodosHandler(w http.ResponseWriter, r *http.Request) {
 	// Implement logic to fetch and display all todos from the database
    
 	// Example code to display a list of todos
 	todos := []Todo{
 		{ID: "1", Title: "Buy groceries"},
 		{ID: "2", Title: "Complete assignment"},
 		{ID: "3", Title: "Call mom"},
 	}
    
 	for _, todo := range todos {
 		w.Write([]byte(todo.Title + "\n"))
 	}
 }

Implement the logic to create a new todo and store it in the database in the createTodoHandler function:

 func createTodoHandler(w http.ResponseWriter, r *http.Request) {
 	// Implement logic to create a new todo and store it in the database
    
 	// Example code to create a new todo
 	newTodo := Todo{ID: "4", Title: "Walk the dog"}
    
 	// Store the new todo in the database
    
 	w.Write([]byte("Todo created successfully"))
 }

Implement the logic to fetch and display a specific todo from the database in the getTodoHandler function:

 func getTodoHandler(w http.ResponseWriter, r *http.Request) {
 	// Implement logic to fetch and display a specific todo from the database
    
 	// Example code to fetch and display a specific todo
 	todoID := mux.Vars(r)["id"]
 	todo := Todo{ID: todoID, Title: "Example Todo"}
    
 	w.Write([]byte(todo.Title))
 }

Implement the logic to update a specific todo in the database in the updateTodoHandler function:

 func updateTodoHandler(w http.ResponseWriter, r *http.Request) {
 	// Implement logic to update a specific todo in the database
    
 	// Example code to update a specific todo
 	todoID := mux.Vars(r)["id"]
 	updatedTodo := Todo{ID: todoID, Title: "Updated Todo"}
    
 	// Update the todo in the database
    
 	w.Write([]byte("Todo updated successfully"))
 }

Implement the logic to delete a specific todo from the database in the deleteTodoHandler function:

 func deleteTodoHandler(w http.ResponseWriter, r *http.Request) {
 	// Implement logic to delete a specific todo from the database
    
 	// Example code to delete a specific todo
 	todoID := mux.Vars(r)["id"]
    
 	// Delete the todo from the database
    
 	w.Write([]byte("Todo deleted successfully"))
 }

With the functionality implemented, you can now create, update, and delete todos in your Todo List web application.

Conclusion

In this tutorial, we have built a Todo List web application using the Go programming language. We covered the basics of web programming in Go, including routing with Gorilla Mux, handling requests and responses, and storing data. By following this tutorial, you have learned how to create a web application and add functionality to it. Feel free to expand on this project and customize it to fit your needs.

Remember to refer to the code examples and explanations provided in this tutorial whenever you encounter any issues or want to explore further possibilities for your Todo List web application. Happy coding!

Published: 24 October 2019