[PyDev] Project 5 : Use public data of Open Food Facts project

Last version of this document is available on github.

Approach

Introduction

Search substitute for food product in the Open Food Facts DB and displays products informations

The user can:

interact with the system in the terminal
save products for later retrieval

This project was created for studying purpose, to train these tools :

manipulating Open Food Facts REST API with Requests
connecting a MySQL DB with PyMySQL
using a MariaDB server with a MySQL CLI (mycli)
creating an interactive script

t purpose. It can evolve beyond for training with PyMySQL, Requests and OpenFF API.

The whole exercise description is available on OpenClassrooms site.

The project is hosted on github.

Workflow

plan the work : features, scripts, files, functions tool needed…
create features, grouped in autonomous packages
organize features in a kanban type table
write documentation, as text & doctest
write code

Code construction

To build the script, I followed this approach :

take in hand the necessary tools
get started with some the basic features/tools
finally add more specific detailed functionalities

Concretely :

familiarize myself with the data stored in the DB (playing with the CSV file)
use the API in a basic way (see get_product() function)
imagine the main SQL queries
use PyMySQL in a basic way
create an interface object with the DB
create the script interfacing the API and the DB
create the DB CLI used by the user

Code organization

config.py : configuration
cli.py : user interface script
db.py : DB class used by all scripts
function.py : files with functions used by all scripts
populate-db.py : back-office script used to populate DB using API
create-db-loff.sql : back-office script used to creates local (empty) DB
doc : documentation folder
legacy-sql : first SQL manipulations (just for memories)
sample : Open Food Facts category & product JSON files (to work offline and lower API usage)

Difficulties encountered

How to interact between the API and the DB

Before exchanging with my mentor I think about using the CSV file as a resource for creating the local DB and then the API will allow to keep it up to date afterwards. This version would have required a large amount of time without bringing a gain of interest.

Creating class Db():

Tests are not required in this project but, using doctest is a precious help when I code. It was an opportunity for me to use them in a class, dealing with trouble like «where the test are useful»?

Stay in the scope

Not easy to frame initial specifications that have a part of interpretation. Similarly for the levels of details, it is easy to slip into a design where they are places for evolution and/or new features.

4.0 KiB Raw Blame History