Designing our web app

The design phase is the most important in any software project as one small mistake in designing becomes very costly to fix that later. In most projects, there are a few solutions applied to mistakes in design, they are just glued together until it becomes impossible to go forward. The term is called technical debt.

Our webapp is going to be a todo list manager for multiple users. It'll have the following features:

Ability to add/delete/modify task.
Ability to mark tasks as complete/incomplete.
Display the tasks as a one column list.
Ability to switch modes between pending/completed/deleted tasks.
Display notifications like note added/deleted/archived. 
Search for text and highlight the text in the search results page.
Login/Sign up.

The Design

Translating our design to API, we get the following.

URL	Method	Description
/add/	POST	add new task
/	GET	show pending tasks
/complete/	GET	show completed tasks
/deleted/	GET	show deleted tasks
/edit/	POST	edit post
/edit/	GET	show the edit page
/trash/	POST	trash post to recycle bin
/delete/	POST	permanently delete post
/complete/	POST	mark post as complete
/login/	POST	do the login
/login/	GET	show login page
/logout/	POST	log the user out
/restore/	POST	restore that task
/update/	POST	update task
/change/	GET	will allow changing password
/register/	GET	show the register page
/register/	POST	will add entries into database

file ~/main/main.go

package main
import (
    "log"
    "net/http"
)

func main() {
    http.HandleFunc("/complete/", CompleteTaskFunc)
    http.HandleFunc("/delete/", DeleteTaskFunc)
    http.HandleFunc("/deleted/", ShowTrashTaskFunc)
    http.HandleFunc("/trash/", TrashTaskFunc)
    http.HandleFunc("/edit/", EditTaskFunc)
    http.HandleFunc("/completed/", ShowCompleteTasksFunc)
    http.HandleFunc("/restore/", RestoreTaskFunc)
    http.HandleFunc("/add/", AddTaskFunc)
    http.HandleFunc("/update/", UpdateTaskFunc)
    http.HandleFunc("/search/", SearchTaskFunc)
    http.HandleFunc("/login", GetLogin)
    http.HandleFunc("/register", PostRegister)
    http.HandleFunc("/admin", HandleAdmin)
    http.HandleFunc("/add_user", PostAddUser)
    http.HandleFunc("/change", PostChange)
    http.HandleFunc("/logout", HandleLogout)
    http.HandleFunc("/", ShowAllTasksFunc)

    http.Handle("/static/", http.FileServer(http.Dir("public")))
    log.Print("running on port 8080")
    log.Fatal(http.ListenAndServe(":8080", nil))
}

Create all functions we mentioned above and make the necessary changes as per one definition that we show below in this file.

func ShowAllTasksFunc(w http.ResponseWriter, r *http.Request) {
    var message string
    if r.Method == "GET" {
        message = "all pending tasks GET"
    } else {
        message = "all pending tasks POST"
    }
    w.Write([]byte(message))
}

After you create these functions run the server as below,

[Tasks] $ go build
[Tasks] $ ./Tasks

In your browser type localhost:8080 and type all these URLs and see what message you get.

Homework

Check the documentation for http.ResponseWriter and http.Request objects and get to know all the variables/functions/constants for http package and these two which we mentioned.

Links

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