Myapp Template

Welcome to the myapp app! Please use this as a template to create your own app

• SQLite - An embedded database to store all our movies
• Python - A fantastic, simple language we use to communicate with our database
• SQLModel - A python library that allows you to communicate with your database. This is an Object Relational Mapping (ORM) library.
• Textual - An awesome Terminal Movie Interface (TUI) that allows us to draw interactive graphics on our terminal
• Prompt-toolkit - An awesome library that allows you one to create a custom Read-Evaluate-Print-Loop (REPL)

Installation

Just type in pip install -e .

Running the Demo

There are three (3) applications we created to interact with our database. Open up your terminal/shell and type one of the following commands:

1. myapp-create-db - This will create the database for us. This must be executed at least one time before any other command. The database will be stored in src/myapplist/database/database.db
2. myapp-repl - This will launch the repl app. You will issue commands by entering them into the repl.
3. myapp-tui - This will launch the tui app. You issue commands by clicking the widgets in your terminal.

myapp-repl and myapp-tui have the same capabilities when it comes to adding worklists and tasks. They are just different frontends to talk to the database.

Clear Tables and Data

Anytime you want to clear the database and start fresh, just type myapp-create-db into your shell.

Database Design

There are two tables created in this app: Movie

erDiagram
    Movie {
        int id PK
        string title
        string director
    }

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Walkthrough

All the main code lives inside the folder src/myapp:

myapp
├─ tui
│  ├─ widgets
│  │  └─ select.py
│  ├─ style.css
│  └─ app.py
├─ repl
│  ├─ helper.py
│  ├─ console.py
│  └─ app.py
├─ db.py
└─ database
   ├─ database.db

Let's talk about each section.

database

The database folder holds the file database.db. This is a SQLite database file that stores all the data for our app. YOu can open this database with Beekeeper or even SQLite browser.

db.py

This is our python module that contains the definition of the tables in our database. We are using SQLModel to define the tables. For example

class Movie(SQLModel, table=True):  # 
    id: Optional[int] = Field(default=None, primary_key=True)  # this will autoincrement by default
    title: str
    director: str 

defines a class called Movie that inherits from SQLModel. This will ensure that a table called movie may be created. The data types of the fields are the type hints in Python.

We also create helper functions that help us talk to the database:

def get_movies() -> List[Movie]:
    with Session(engine) as session:
        return list(session.query(Movie).all())

This functions creates a Session with our database where we can query all the rows in the Movie table. Usually you would do this with SQL like:

SELECT *
FROM movie

However, the ORM allows us to do this all within Python (and the ORM handles writing SQL). This function will return a list of Movie objects (the rows in our table).

repl

The repl is created using prompt-toolkit. The main application is under the file app.py. The files console.py and helper.py provide function and objects that the help app.py.

The basic idea is we have a while loop that repeatedly asks for commands. We execute those commands (which are often reading or writing to the database) and loop again.

tui

This folder contains all the code for the tui interface. The main app is inside the file app.py. All the styles of the app, which configure how the app looks, are in style.css. This is a much more advanced interface than the repl interface.