finish v1

README.md

@@ -63,6 +63,8 @@ Flask-Migrate in your virtual environment. Enter the following in
 `flask_app.py`:
 
 ```py
+# app/flask_app.py
+
 #!/usr/bin/env python3
 
 from flask import Flask
@@ -95,6 +97,8 @@ contains all of the same fields as attributes. This behaves similarly to
 Let's create some models!
 
 ```py
+# app/models.py
+
 from flask_sqlalchemy import SQLAlchemy
 
 db = SQLAlchemy()
@@ -111,7 +115,7 @@ class Owner(db.Model):
         return f'<Pet Owner {self.name}>'
 
 class Pet(db.Model):
-    __tablename__ = 'users'
+    __tablename__ = 'pets'
 
     id = db.Column(db.Integer, primary_key=True)
     name = db.Column(db.String)
@@ -136,15 +140,181 @@ from our models using Flask-Migrate.
 
 ### Flask-Migrate
 
+Like Flask-SQLAlchemy with vanilla SQLAlchemy, Flask-Migrate is a wrapper for
+Alembic with minimal changes to allow it to integrate better with Flask
+applications. This can become a bit confusing, especially from the command line.
+Don't worry though- we'll discuss those nuances in detail here!
+
+Modify `flask_app.py` to mirror the following:
+
+```py
+# app/flask_app.py
+
+#!/usr/bin/env python3
+
+from flask import Flask
+from flask_sqlalchemy import SQLAlchemy
+from flask_migrate import Migrate
+
+from models import db
+
+app = Flask(__name__)
+app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///app.db'
+
+db = SQLAlchemy(app)
+
+migrate = Migrate(app, db)
+
+db.init_app(app)
+
+if __name__ == '__main__':
+    app.run()
+
+```
+
+We have imported the `Migrate` class here to set up our migrations using our
+Flask application instance and our `SQLAlchemy` instance. We also initialized
+our application for use within our database configuration with
+`db.init_app(app)`.
+
+> **NOTE:** `db.init_app(app)` is an easy step to forget! (So don't!)
+
+We're ready to get started with our migrations. The commands for Flask-Migrate
+are identical to those in Alembic, with the exception of using `flask db` in
+place of `alembic` in commands. Run the following from the `app/` directory in
+the command line:
+
+```console
+$ export FLASK_APP=flask_app.py
+$ flask db init
+# => /python-p4-flask-sqlalchemy/.venv/lib/python3.10/site-packages/flask_sqlalchemy/__init__.py:872: FSADeprecationWarning: SQLALCHEMY_TRACK_MODIFICATIONS adds significant overhead and will be disabled by default in the future.  Set it to True or False to suppress this warning.
+# =>   warnings.warn(FSADeprecationWarning(
+# => /python-p4-flask-sqlalchemy/.venv/lib/python3.10/site-packages/flask_sqlalchemy/__init__.py:872: FSADeprecationWarning: SQLALCHEMY_TRACK_MODIFICATIONS adds significant overhead and will be disabled by default in the future.  Set it to True or False to suppress this warning.
+# =>   warnings.warn(FSADeprecationWarning(
+# =>   Creating directory /python-p4-flask-sqlalchemy/app/migrations ...  done
+# =>   Creating directory /python-p4-flask-sqlalchemy/app/migrations/versions ...  done
+# =>   Generating /python-p4-flask-sqlalchemy/app/migrations/script.py.mako ...  done
+# =>   Generating /python-p4-flask-sqlalchemy/app/migrations/env.py ...  done
+# =>   Generating /python-p4-flask-sqlalchemy/app/migrations/README ...  done
+# =>   Generating /python-p4-flask-sqlalchemy/app/migrations/alembic.ini ...  done
+# =>   Please edit configuration/connection/logging settings in '/python-p4-flask-sqlalchemy/app/migrations/alembic.ini' before proceeding.
+```
+
+Let's heed that warning and set `SQLALCHEMY_TRACK_MODIFICATIONS` to `False`.
+
+```py
+# app/flask_app.py
+
+...
+app = Flask(__name__)
+app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///app.db'
+app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
+...
+
+```
+
+We're getting a warning to change `app/migrations/alembic.ini` before we
+continue, but our `app/flask_app.py` configuration already manages all of our
+unique environment variables. We can jump straight into migrating:
+
+```console
+$ flask db revision --autogenerate -m'Create tables owners, pets'
+# => INFO  [alembic.runtime.migration] Context impl SQLiteImpl.
+# => INFO  [alembic.runtime.migration] Will assume non-transactional DDL.
+# =>   Generating /python-p4-flask-sqlalchemy/app/migrations/versions/a48f1fc37e07_create_tables_owners_pets.py ...  done
+```
+
+...and pushing those migrations to our database:
+
+```console
+$ flask db upgrade head
+# => INFO  [alembic.runtime.migration] Context impl SQLiteImpl.
+# => INFO  [alembic.runtime.migration] Will assume non-transactional DDL.
+# => INFO  [alembic.runtime.migration] Running upgrade  -> 1c84830b3fc2, Create tables owners, pets
+```
+
+We've created a database with Flask-SQLAlchemy and Flask-Migrate! Open
+`app/db/app.db` and you should see the fruits of your labor:
+
+![Screenshot of SQLite database with three tables: alembic_version, owners, and
+pets](
+https://curriculum-content.s3.amazonaws.com/python/flask-sqlalchemy-owners-pets-db.png)
+
 ***
 
-## Resources
+## Conclusion
+
+Flask extensions give us many opportunities to add functionality to our
+applications while writing minimal code for configurations. We saw how to
+create a database with Flask-SQLAlchemy and Flask-Migrate, and some among us
+may have even noticed that we wrote slightly _less_ code than we did when using
+SQLAlchemy by itself!
+
+In the next lesson, we will look into working with data in Flask applications
+using Flask-SQLAlchemy.
+
+***
+
+## Solution Code
+
+```py
+# app/flask_app.py
 
-- [API - Pallets Projects](https://flask.palletsprojects.com/en/2.2.x/api/)
-- [HTTP request methods - Mozilla][moz_http]
-- [HTTP response status codes - Mozilla][moz_http_status]
-- [Response Objects - Pallets Projects][response]
+from flask import Flask
+from flask_sqlalchemy import SQLAlchemy
+from flask_migrate import Migrate
+
+from models import db
+
+app = Flask(__name__)
+app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///db/app.db'
+app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
+
+migrate = Migrate(app, db)
+
+db.init_app(app)
+
+if __name__ == '__main__':
+    app.run()
+
+```
+
+```py
+# app/models.py
+
+from flask_sqlalchemy import SQLAlchemy
+
+db = SQLAlchemy()
+
+class Owner(db.Model):
+    __tablename__ = 'owners'
+
+    id = db.Column(db.Integer, primary_key=True)
+    name = db.Column(db.String, unique=True)
+
+    pets = db.relationship('Pet', backref='owner')
+
+    def __repr__(self):
+        return f'<Pet Owner {self.name}>'
+
+class Pet(db.Model):
+    __tablename__ = 'pets'
+
+    id = db.Column(db.Integer, primary_key=True)
+    name = db.Column(db.String)
+    species = db.Column(db.String)
+
+    owner_id = db.Column(db.Integer, db.ForeignKey('owners.id'))
+
+    def __repr__(self):
+        return f'<Pet {self.name}, {self.species}>'
+
+```
+
+***
+
+## Resources
 
-[moz_http]: https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods
-[moz_http_status]: https://developer.mozilla.org/en-US/docs/Web/HTTP/Status
-[response]: https://flask.palletsprojects.com/en/2.2.x/api/#response-objects
+- [Quickstart - Flask-SQLAlchemy](https://flask-sqlalchemy.palletsprojects.com/en/2.x/quickstart/#)
+- [Flask-Migrate](https://flask-migrate.readthedocs.io/en/latest/)
+- [Flask Extensions, Plug-ins, and Related Libraries - Full Stack Python](https://www.fullstackpython.com/flask-extensions-plug-ins-related-libraries.html)

app/flask_app.py

@@ -7,9 +7,8 @@
 from models import db
 
 app = Flask(__name__)
-app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///app.db'
-
-db = SQLAlchemy(app)
+app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///db/app.db'
+app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
 
 migrate = Migrate(app, db)