Hello,
In this segment, we are going to look at how to interact with the database in the flask.
BTW Flask can easily bond with many databases. So, you can choose your own
But in this segment, we are using Flask-SQLAlchemy as our database.
Lots of trash talks lets get started.
Installing the Flask-SQLAlchemy
$ pip install -U Flask-SQLAlchemy
pip list
Package Version
---------------- -----------
click 7.1.2
config 0.5.0.post0
Flask 1.1.2
Flask-SQLAlchemy 2.4.4
itsdangerous 1.1.0
Jinja2 2.11.2
MarkupSafe 1.1.1
pip 9.0.1
pkg-resources 0.0.0
setuptools 39.0.1
SQLAlchemy 1.3.19
Werkzeug 1.0.1
Configuring Flask-SQLAlchemy For Your Application
There are a few configuration variables we need to set up before interacting with our database.
Open config.py
<root>/config.py
from os import environ, path
from dotenv import load_dotenv
import os
basedir = path.abspath(path.dirname(__file__))
load_dotenv(path.join(basedir, '.env'))
class Config(object):
"""Base config."""
SECRET_KEY = "qeqwrwe1231weerw"
STATIC_FOLDER = 'static'
TEMPLATES_FOLDER = 'templates'
SQLALCHEMY_DATABASE_URI = os.environ.get('DATABASE_URL') or \
'sqlite:///' + os.path.join(basedir, 'database.db')
SQLALCHEMY_TRACK_MODIFICATIONS = False
DEBUG = True
class Production(Config):
FLASK_ENV = 'production'
DEBUG = False
TESTING = False
class Development(Config):
FLASK_ENV = 'development'
DEBUG = True
TESTING = True
There are a few variables here which are specific to Flask-SQLAlchemy:
SQLALCHEMY_DATABASE_URI: the connection string we need to connect to our database.SQLALCHEMY_TRACK_MODIFICATIONS: I just always set this to False.
At this movement, we haven’t created our database file
Create a file database.db in you <root> folder
.
├── /application
├── /env
├── config.py
├── database.db
├── requirements.txt
└── wsgi.py
Initiating Flask-SQLAlchemy
In this, we are using the Flask Application Factory method for initiating our app.
First of all, we need to import SQLAlchemy
from flask_sqlalchemy import SQLAlchemy
and now we need to create an SQLAlchemy to an object so we can use our database
db = SQLAlchemy()
Open __init__.py
<root>/application/__init__.py
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
app = Flask(__name__)
db = SQLAlchemy()
def create_app():
if app.config["ENV"] == "production":
app.config.from_object("config.Production")
else:
app.config.from_object("config.Development")
db.init_app(app)
with app.app_context():
from application import views
from application import admin_views
db.create_all() # Create sql tables for our data models
return app
You have noticed create_app()
Having wrapped the app object inside of the create_app function, we still need a way to access it other than calling the function itself.
Now we need to import the create_app function
Open wsgi.py
from application import create_app
app = create_app()
if __name__ == '__main__':
app.run()
Creating Database Models
Create a models.py file in our application directory.
import the db object that we created in __init__.py
.
├── /application
│ ├── static
│ ├── templates
│ ├── __init__.py
│ ├── adminviews.py
│ ├── models.py
│ └── views.py
├── /env
├── config.py
├── database.db
├── requirements.txt
└── wsgi.py
open model.py
from . import db
class Todos(db.Model):
__tablename__ = 'todos'
id = db.Column(
db.Integer,
primary_key=True
)
todo = db.Column(
db.String(64),
index=False,
unique=True,
nullable=False
)
def __repr__(self):
return '<Todo {}>'.format(self.todo)
Creating Our First Todo
Let’s create new routes in our views.py
Firstly import models and db object
from .models import db, Todos
And add a route to add tasks in the database
@app.route('/todo/<task>')
def todos(task):
new_todo = Todos(todo = task)
db.session.add(new_todo) # Adds new Todo record to database
db.session.commit() # Commits all changes
return "<h1> You have successfully created your task : "+task+"</h1>"
Save everything and start your application
And run application
flask run
Done!!
Hit: http://127.0.0.1:5000/todo/siddythings
Wrapping up
In this segment we have learn about seting up the database.
Try to do some project by yourself.
In the upcoming segment we are learing about showing querying the records.