Solved: save changes flask sqlalchemy

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Flask SQLAlchemy is a Python-based framework that allows developers to work efficiently with databases. It is a way to bridge the gap between SQL queries and Python. Flask SQLAlchemy is, mostly, a Pythonic way to interact with databases. Flask SQLAlchemy offers a high-level, Pythonic, and user-friendly interface to SQL databases, giving you the power of SQL with the ease of Python. The key advantage of using Flask SQLAlchemy is that it provides an abstracted layer over pure SQL, allowing you to leverage the full power of SQL databases without the need to write complex SQL scripts.

Saving Changes in Flask SQLAlchemy

Saving changes with Flask SQLAlchemy involves 2 main steps: defining the changes and committing them.

First, you operate on your objects like they’re regular Python objects. Then, when you’re ready, you call session.commit() to save all the changes at once. This process is commonly referred to as a “transaction”.

    from flask_sqlalchemy import SQLAlchemy
    db = SQLAlchemy()
    
    class User(db.Model):
        id = db.Column(db.Integer, primary_key=True)
        name = db.Column(db.String(50), nullable=False)

    # Initialize a new user instance
    new_user = User(name='John Doe')

    # Add the new user to the session
    db.session.add(new_user)

    # Commit the session
    db.session.commit()

Step-by-step Explanation of the Code

1. First, we import the SQLAlchemy class from the flask_sqlalchemy module.
2. Next, we create an instance of this class which we will use to interact with our database.
3. We define a User model with id and name fields.
4. We then initialize a new User instance.
5. Next, we add this instance to our SQLAlchemy session. This queues up the object to be inserted into the database.
6. Finally, we commit the session, which executes the database operation.

Libraries involved in Flask SQLAlchemy

Flask-SQLAlchemy is work based on a few Python libraries. The first is Flask, a lightweight web server framework for Python.

The other two important libraries are SQLAlchemy and Werkzeug.

SQLAlchemy provides a full suite of well known enterprise-level persistence patterns, designed for efficient and high-performing database access.

Werkzeug is a Python utility library for Python, widely used in many Python web frameworks including Flask.

In conclusion, saving changes in Flask SQLAlchemy is a straightforward process and its libraries provide a clear method to engage an SQL database using Python. With a good understanding of the steps and functions involved, it is easy to start executing complex transactions and queries.