PythonPostgresLab

PythonPostgresLab

A CLI (Command Line Interface) written in python to query a PostgreSQL database. Lab realized as a student at Ecole Centrale de Nantes (ECN).

Prerequisites

What you need to get this project running. These commands were tested on a debian based system (Ubuntu 18.04 LTS).

Python packages

Pip

If not installed yet, you need to get pip, the python package manager :

sudo apt install python3-pip

PyInquirer

For easy CLI python interfaces :

sudo pip3 install pyinquirer

Postgres

To install PostgreSQL driver :

sudo pip3 install postgres

PostgreSQL database

I strongly recommand to know how to run an instance of postgreSQL. The schema is a model of a logistics company.

Install a postgreSQL instance

Install postgreSQL :

sudo apt install postgresql

Start service :

sudo service postgresql start

Create the database

Connect with postgres profile :

sudo su postgres

Create the database :

psql -f SQL/create_db.sql postgres

Populate database with tables :

psql -d logistics -f SQL/create_tables.sql postgres

Populate tables with sample data :

psql -d logistics -f SQL/populate_tables.sql postgres

If needed you can adapt the password of postgres user (or any user you want) :

psql -c "alter user postgres password 'postgres_password'"

Repository structure

How files are organized.

Python files with app_ prefix

Python application launched by user. For instance, to run the application as a customer, run the following command

python3 app_customer.py

File named test_pyinquirer.py

Execute this file with python to check if PyInquirer is correctly installed. No need of PostgreSQL to start this file.

File named basic_display.py

Contains a class that perform simple prints to show information to users.

Folder named cli

cli stands for command line interface. You will find every class which asks inputs to user. That's where the PyInquirer module is used.

Folder named consumer

Contains code to interact with the database. The class Consumer in consumer.py holds a connection to perform SQL queries against the database. If you need to change the credentials used to log on the database, please modify credentials.py.

Folder named SQL

Contains the SQL files used in the prerequisites section to create and populate the logistics database used by application.

Folder named model

Contain simple python classes mapped to relational model. Used in basic_display.py to get the code more readable.