done: Define and Access the Database

flaskr/__init__.py

@@ -31,4 +31,7 @@ def create_app(test_config=None):
     def hello():
         return 'Hello, World!'
 
+    from . import db
+    db.init_app(app)
+
     return app

flaskr/db.py

@@ -0,0 +1,49 @@
+#!/usr/bin/env python3
+
+import sqlite3
+from datetime import datetime
+
+import click
+from flask import current_app, g
+
+
+def get_db():
+    if 'db' not in g:
+        g.db = sqlite3.connect(
+            current_app.config['DATABASE'],
+            detect_types=sqlite3.PARSE_DECLTYPES
+        )
+        g.db.row_factory = sqlite3.Row
+
+    return g.db
+
+
+def close_db(e=None):
+    db = g.pop('db', None)
+
+    if db is not None:
+        db.close()
+
+
+def init_db():
+    db = get_db()
+
+    with current_app.open_resource('schema.sql') as f:
+        db.executescript(f.read().decode('utf8'))
+
+
+@click.command('init-db')
+def init_db_command():
+    """Clear the existing data and create new tables."""
+    init_db()
+    click.echo('Initialized the database.')
+
+
+sqlite3.register_converter(
+    "timestamp", lambda v: datetime.fromisoformat(v.decode())
+)
+
+def init_app(app):
+    app.teardown_appcontext(close_db)
+    app.cli.add_command(init_db_command)
+

flaskr/schema.sql

@@ -0,0 +1,17 @@
+DROP TABLE IF EXISTS user;
+DROP TABLE IF EXISTS post;
+
+CREATE TABLE user (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  username TEXT UNIQUE NOT NULL,
+  password TEXT NOT NULL
+);
+
+CREATE TABLE post (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  author_id INTEGER NOT NULL,
+  created TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+  title TEXT NOT NULL,
+  body TEXT NOT NULL,
+  FOREIGN KEY (author_id) REFERENCES user (id)
+);