PythonHandbook

Just a text document with some helpful commands for Python & Linux. Contains database and version control information as well.

---

​

A Python handbook for:

• Python (Flask, FastAPI, Pytest)

• Databases (PostgreSQL).

• Git, Docker, Poetry.

• Shell & Terminal commands (Linux)

PYTHON DEBUGGER (PDB)

interactive - to activate Python shell while debugging with Python Debugger.

Databases (PostgreSQL, Redis)

POSTGRES:

    
1) psql -h localhost -U postgres ----> activate the database through terminal
2) \l ----> List available databases
3) \dt ----> List available tables
4) \d table_name ---> Describe a table (columns, types, modifiers, etc)

Creating a user and granting them access:
1) sudo -u postgres psql
2) postgres=# create database mydb;
3) postgres=# create user myuser with encrypted password 'mypass';
4) postgres=# grant all privileges on database mydb to myuser;

Ubuntu, set global configs through terminal:
1) export POSTGRES_URL="127.0.0.1:5432"
2) export POSTGRES_USER="postgres"
3) export POSTGRES_PW="dbpw"
4) export POSTGRES_DB="test"

1. https://medium.com/coding-blocks/creating-user-database-and-adding-access-on-postgresql-8bfcd2f4a91e
   - Creating users / databases, permissions etc.

REDIS:

Step 1.

Setup & Install (For Linux)

$ sudo apt update
$ sudo apt install redis-server

# This will download and install Redis and its dependencies.
# Open this file:
$ sudo nano /etc/redis/redis.conf
# Edit the line `supervised no` to `supervised systemd`. Press CTRL + X, Y, then ENTER to save the file and exit.

# Then, restart the Redis service to reflect the changes you made to the configuration file:
$ sudo systemctl restart redis.service

Step 2.

Testing Redis

# Start by checking that the Redis service is running:
$ sudo systemctl status redis

# If `active` is on `running` then everything is good so far.
# Here, you can see that Redis is running and is already enabled, meaning that it is set to start up every time the server boots.

# To test that Redis is functioning correctly:
$ redis-cli

# In the prompt that follows, test connectivity with the ping command:
$ 127.0.0.1:6379> ping # IF OK, this should return `PONG`.

# Next, check that you’re able to set keys by running:
$ 127.0.0.1:6379> set test "It's working!"

# Retrieve the value by typing:
$ 127.0.0.1:6379> get test

# As a final test, we will check whether Redis is able to persist data even after it’s been stopped or restarted. To do this, first restart the Redis instance:
$ 127.0.0.1:6379> exit
$ sudo systemctl restart redis

# Then connect with the command-line client again:
$ redis-cli

# And confirm that your test value is still available.
$ 127.0.0.1:6379> get test

Reference Link: https://www.digitalocean.com/community/tutorials/how-to-install-and-secure-redis-on-ubuntu-20-04

Git, Poetry, Pip -- Version Control --

Git commands:

**git log --graph --oneline --decorate --all ----> this shows the previous changes, more information about tags and such.**
**git tag v1.0.15 -----> Creates a tag, it's like a branch but it's unmovable.**
**git commit -a -m "Add account stats endpoint"  -----> for commits on git**

Poetry:

poetry install -----> this installs the poetry in the folder for the first time.
poetry shell ----> Creates / Activates the virtual environment.
poetry update -----> this updates the packages / installs them in the machine.
deactive ----> Exits the current activated virtual environment.

*TO RUN CERTAIN TESTS*
poetry run python -m py.test tests/routes/test_campaign_shared_sets.py::[name_of_the_test] -vv -x --pdb

*TO RUN THE COMPLETE FILE*
poetry run python -m py.test tests/routers/ad_groups/test_critera.py -vv -x --pdb      

Docker

Clean up docker space:

# check docker volume disk usage
----> sudo du -sh /var/lib/docker/volumes

# check total disk usage
----> df -h /

# clear up space
----> docker volume prune

05. Terminal

Open a file to edit it in terminal (for example, a text file)

$ nano [directory of the file] ---> example ---> nano ~/.profile

$ sudo -H nautilus ---> Opens up folder explorer. With this, you can copy/paste/extract to folders that require permissions.

Useful Links:

Create user, database, access ---> https://medium.com/coding-blocks/creating-user-database-and-adding-access-on-postgresql-8bfcd2f4a91e

Flask, SQLAlchemy and Postgres ---> https://build.vsupalov.com/flask-sqlalchemy-postgres/

Discord Bot ---> https://discordpy.readthedocs.io/en/stable/faq.html#how-do-i-send-a-message-to-a-specific-channel

---

---

Basics

1. Project initialziation commands:

$ mkdir myapp && cd myapp ---> Creates a folder named myapp and switches to that directory.

$ go mod init myapp ---> The go mod init command creates a go.mod file to track your codes dependencies.

$ go get ---> Imports a framework from github. EXAMPLE ---> `$ go get github.com/labstack/echo/v4`  (echo framework)

NOTE: 'init()' function runs before 'main()'. 'main()' function runs after 'init()'

---