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How to create a to-do list app with Flask

Njoku Ifeanyi Gerald

Flask is a Python micro web framework. Flask is “micro” because it omits native tools and libraries for an “only installs what you need” approach.

In this shot, we will create a to-do app where you can add to-dos (activities) and even mark when you are done with any of the activities. This will give you a grasp of the popular web framework Flask.

Install the dependencies

First, run the following commands to install the required dependencies:

pip install pipenv 
pipenv shell 
pipenv install Flask
pipenv install Flask-SQLAlchemy
pipenv install SQLAlchemy

SQLalchemy is an Object Relational Mapper(ORM).

Create a file and name it app.py. Let’s get to the code.

app.py

from flask import  Flask, request, render_template, url_for, redirect
from flask_sqlalchemy import SQLAlchemy
from sqlalchemy.sql import func
from sqlalchemy import desc

#first step in starting a flask app
app = Flask(__name__)

#configuring the database
app.config['SQLALCHEMY_DATABASE_URI']= 'sqlite:///test.db'
app.config['SQLALCHEMY_TRACK_MODIFICATIONS']=False

#initializing sqlalchemy
db=SQLAlchemy(app)



#creating of the model
class Note(db.Model):
    id= db.Column(db.Integer(), primary_key=True)
    text = db.Column(db.String(100))
    complete =db.Column(db.Boolean())
    date = db.Column(db.DateTime(timezone=True), default=func.now())

 
#home route
@app.route('/')
def home():
    # making the data to render from a descending order according to the datetime
    incomplete =Note.query.filter_by(complete=False).order_by(desc(Note.date)).all()
    complete = Note.query.filter_by(complete=True).order_by(desc(Note.date)).all()

    return render_template('home.html', incomplete =incomplete, complete=complete)

#route for adding todos
@app.route('/add', methods=['POST'])
def add():
    note = Note(text=request.form['todoitem'], complete=False)
    db.session.add(note)
    db.session.commit()
    return redirect (url_for('home'))

#route to mark completed task
@app.route('/complete/<id>')
def complete(id):
    note = Note.query.filter_by(id=int(id)).first()
    note.complete = True
    db.session.commit()

    return redirect (url_for('home'))

#initiating the flask framework
if __name__ == "__main__":
    app.run(debug=True)

Create a folder and name it “templates.” Inside the “templates” folder, create a file and name it “home.html”, then add the code below:

home.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.1.1/dist/css/bootstrap.min.css" rel="stylesheet" 
        integrity="sha384-F3w7mX95PdgyTmZZMECAngseQB83DfGTowi0iMjiWaeVhAn4FJkqJByhZMI3AhiU" crossorigin="anonymous">
</head>
<body>
<div class="container">
    <h2>Todo List</h2>
    <div>add a new todo list</div>
    <form action="{{ url_for('add') }}" method="POST" >
            <input class="form-control" type="text" name="todoitem">
            <input value="Add item" type="submit"  >

    </form>
    <div class="form-group">
        <h3>incomplete items</h3>
        <ul>
            {% for todo in todos %}
            <li style="font-size: 30pt">{{ todo.text }} <a href="{{ url_for('complete', id=todo.id) }}">mark as complete</a> </li>
            {% endfor %}
        </ul>
            <h3>incomplete items</h3>
            <ul>
                {% for todo in incomplete %}
                 <li style="font-size: 30pt">{{ todo.text }} <a href="{{ url_for('complete', id=todo.id) }}">mark as complete</a> </li>
                {% endfor %}
            </ul>
            <h3>complete</h3>
            <ul>
                {% for todo in complete %}
                <li style="font-size: 30pt">{{ todo.text }}</li>
                {% endfor %}
            </ul>

    </div>
</div>
<script src="https://cdn.jsdelivr.net/npm/bootstrap@5.1.1/dist/js/bootstrap.bundle.min.js" 
    integrity="sha384-/bQdsTh/da6pkI1MST/rWKFNjaCP5gBSY4sEBT38Q/9RBh9AH40zEOg7Hlq2THRZ" crossorigin="anonymous">
</script>
</body>
</html>

In your terminal, run this code to create a database:

python
from app import db
db.create_all()
exit()

Then run:

python app.py

Your app should be up and running locally at http://127.0.0.1:5000/.

You should be able to see something like this:

Conclusion

Flask is used to efficiently build small apps and can save time. It uses an ORM(SQLAlchemy), which helps to easily map out a database. The to-do app shows us how to use Flask to build a to-do app and also make use of ORM to map out the model.

Here is a link to the GitHub repo.

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communitycreator

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Njoku Ifeanyi Gerald
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