Merge pull request #505 from realpython/mvc-legos

brendaweles · web-flow · commit 0b29ad7b244b · 2024-03-11T12:52:08.000-06:00
Add materials for Lego MVC resurfacing
diff --git a/mvc-legos/README.md b/mvc-legos/README.md
@@ -0,0 +1,23 @@
+# Model-View-Controller (MVC) in Python Web Apps: Explained With Legos
+
+This folder contains a minimal Flask example app that supports the explanation of the MVC pattern in [Model-View-Controller (MVC) Explained – With Legos](https://realpython.com/the-model-view-controller-mvc-paradigm-summarized-with-legos/).
+
+To run the app, you'll need to first install [Flask](https://flask.palletsprojects.com/), preferably into a [virtual environment](https://realpython.com/python-virtual-environments-a-primer/):
+
+```sh
+(venv) $ python -m pip install Flask
+```
+
+To create and see the SQLite database file, you can then run `create_db.py`:
+
+```sh
+(venv) $ python create_db.py
+```
+
+Finally, you can start the Flask app by executing `app.py`:
+
+```sh
+(venv) $ python app.py
+```
+
+When you make a request in your browser by typing the URL of your localhost and port 8000, you'll see how Flask renders the single view that this web app defines.
diff --git a/mvc-legos/app.py b/mvc-legos/app.py
@@ -0,0 +1,28 @@
+import sqlite3
+
+from flask import Flask, g, render_template
+
+DATABASE = "./database.db"
+
+app = Flask(__name__)
+
+
+def get_db():
+    db = getattr(g, "_database", None)
+    if db is None:
+        db = g._database = sqlite3.connect(DATABASE)
+    return db
+
+
+@app.route("/")
+def home():
+    """Searches the database for entries, then displays them."""
+    db = get_db()
+    cur = db.execute("SELECT * FROM entries ORDER BY id DESC;")
+    entries = cur.fetchall()
+    print(entries)
+    return render_template("index.html", entries=entries)
+
+
+if __name__ == "__main__":
+    app.run(host="0.0.0.0", port=8000, debug=True)
diff --git a/mvc-legos/create_db.py b/mvc-legos/create_db.py
@@ -0,0 +1,30 @@
+"""Creates and seeds a SQLite example database."""
+import sqlite3
+
+DATABASE = "./database.db"
+
+with sqlite3.connect(DATABASE) as db:
+    try:
+        # Create a table in the database
+        cursor = db.cursor()
+        cursor.execute(
+            """
+            CREATE TABLE IF NOT EXISTS entries (
+                id INTEGER PRIMARY KEY AUTOINCREMENT,
+                title TEXT NOT NULL,
+                text TEXT
+            );
+        """
+        )
+
+        # Insert a new entry to the database
+        cursor.execute(
+            """
+            INSERT INTO entries (title, text) VALUES (?, ?)
+        """,
+            ("spaceship", "My MVP MVC Lego spaceship 🚀"),
+        )
+
+        db.commit()
+    except sqlite3.Error as e:
+        print(f"An error occurred: {e}")
diff --git a/mvc-legos/database.db b/mvc-legos/database.db
diff --git a/mvc-legos/requirements.txt b/mvc-legos/requirements.txt
@@ -0,0 +1,7 @@
+blinker==1.7.0
+click==8.1.7
+flask==3.0.2
+itsdangerous==2.1.2
+jinja2==3.1.3
+markupsafe==2.1.5
+werkzeug==3.0.1
diff --git a/mvc-legos/templates/index.html b/mvc-legos/templates/index.html
@@ -0,0 +1,21 @@
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>Lego Builds</title>
+</head>
+<body>
+    <h1>My Favorite Lego Builds</h1>
+    <p>Here's a list of all my favorite Lego builds:</p>
+    <ul>
+        {% for entry in entries %}
+          <li>
+            <strong>{{ entry[1] }}:</strong> <!-- title -->
+            {{ entry[2] }} <!-- text -->
+          </li>
+        {% else %}
+          <li>No entries yet. Add some!</li>
+        {% endfor %}
+    </ul>
+</body>
+</html>
