🐻 Queries & Using the Shell 🐻

Today’s Topics

• Interacting with models in the shell
• Queries and more queries

🎯 Project: Still Working on Habit Tracker

Habit Tracker is due on Monday. You can do this! 💪 What do you need to figure out in order to finish it?

📖 Read | 📺 Watch | 🎧 Listen

• Database Design for Beginners This is a talk from RailsConf, which is focused on Ruby on Rails (Rails is a framework for building web applications in Ruby, very similiar to Django). The talk is an excellent introduction to how to think about your data model – that is, the logic that drives the decisions you make about the models in your code and the structure of your database. Please watch it all the way through; even though it uses Ruby examples you should be able to get the gist.

Building APIs

This is prep material for the topic we will begin next week.

• RESTful APIs Read up through the “Standard Methods” subsection of the section on “Methods”. You can read more if you want to but it gets pretty deep.
• Safia Abdullah, You and Me Learn All About HTTP
• Web APIs Explained By Selling Goods From Your Farm

🔖 Resources

Using the shell (Django’s interactive REPL, not pipenv shell)

• Official Django docs on using the shell
• Django extensions: shell_plus

🦄 PRO TIPS

• django-debug-toolbar has a SQL panel that will show you the queries you are running in the view.
• With shell_plus, you can see output of all the SQL queries if you run it like this:

python manage.py shell_plus --print-sql

Lookups

• Pretty Printed Video: How Model Queries Work in Django
• Pretty Printed Video: Querying One-to-Many Relationships in Django
• Django QuerySets
• Django Model Managers
• Django Queries: Retrieving Objects
• Field lookups
• Lookups that span relationships
• Lookups with Related objects
• Django Related Objects Reference
• Complex lookups with Q
• F objects

Constraints

• Django Docs: model constraints -> this gives you the general format/syntax
• Django Docs: UniqueConstraint

Aggregate & Annotate

• PrettyPrinted Video: Basics of Django Aggregations
• Pretty Printed Video: How to Use Annotate in Django
• Django docs:Aggregate & Annotate
• Django docs: Combining Aggregations with other QuerySets
• Aggregation Functions (e.g., Avg, Count, Min, Max)

🦉 Code & Notes

• Django Model Queries CheatSheet
• Example Django Recipes