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How to install PostgreSQL

If you are on Arch Linux you can use the following command:

sudo pacman -S postgresql

to install it, but if you are on other Linux distributions just change the Package Manager. Instead, if you are on macOS or Windows, go to the official PostgreSQL website.

Note: If you have never used PostgreSQL on Linux I suggest you follow this guide. {: .notice--info}

Warning: If you use macOS or Windows you must modify the Makefile file to adapt it to your operating system. {: .notice--warning}

After the installation of PostgreSQL you need to use the following commands:

sudo -u postgres initdb -D /var/lib/postgres/data
sudo mkdir -p /var/lib/postgres/data
sudo chown postgres:postgres /var/lib/postgres/data

How to create a database

Once you have downloaded PostgreSQL you need to create the todolist database. Open a terminal and write:

sudo -i -u postgres

this command allows you to change your computer user by selecting the postgres user. Now use the following command to create a database called todolist:

createdb todolist

Now run the command:

psql

you will get something like this:

psql (16.2)
Type "help" for help.

postgres=#

then write:

\c todolist

you should get a message similar to this:

You are now connected to database "todolist" as user "postgres".

Now if you open the src/table.sql file you will find this code inside:

-- Use the following command to create a tasks table on todolist database
CREATE TABLE tasks (
    id SERIAL PRIMARY KEY,
    description TEXT NOT NULL
);

compact this code as follows:

CREATE TABLE tasks (id SERIAL PRIMARY KEY, description TEXT NOT NULL);

and write it immediately after todolist=# and you should get this message:

CREATE TABLE

Now use the following SQL code to see the description and id columns that are part of the tasks table:

SELECT * FROM tasks;

and in particular you should get something similar to this:

id | description 
----+-------------
(0 rows)

Now that you have successfully created the todolist database and created a tasks table to place the information in, you can exit psql using the \q command and then you can switch back to the main user using the exit command.

How to use the todo-app project

If you have performed the previous steps without problems you are ready to use my project. Then clone the repository to your computer using the following command:

git clone https://github.com/AntonioBerna/todo-app.git

For personal security reasons, it is good practice to save your access credentials in the system's environment variables. Then using the touch command we create a setenv.sh file which must contain the following code:

#!/bin/bash

export DATABASE=todolist
export USERNAME=postgres
export PASSWORD= # please complete this
export PORT= # please complete this
echo "Set environment variables for DATABASE, USERNAME, PASSWORD, and PORT."

in particular the PASSWORD should be the login password of your computer, while to find out which connection PORT is you can use the following command:

SELECT setting FROM pg_settings WHERE name = 'port';

Important

To use the previous command you need to log back into psql and then use the sudo -i -u postgres command and then the psql command.

once the setenv.sh file is completed you can use the following commands:

chmod 700 setenv.sh
source setenv.sh

to apply those environment variables to the shell currently in use.

Once you have set the environment variables you will need to compile the program. Then you can use the following command:

make

To test the program we can use the following command:

./bin/todo

so as to obtain:

Usage: ./bin/todo [add|rm|ls] [description|id]

To remove the program from your computer you can use the following command:

make clean

Add tasks

Input:

./bin/todo add homework "go to the toilet"

Output:

Adding of item "homework" successful
Adding of item "go to the toilet" successful

Note: Double quotes " " are optional for single words like coffee, chocolate, tea, ... {: .notice--info}

Print tasks

Input:

./bin/todo ls

Output:

Todo list:
(1) homework
(2) go to the toilet

Delete tasks

Input:

./bin/todo rm 1 2

Output:

Deletion of item 1 successful
Deletion of item 2 successful