How to Effectively Pass Variables Between Pages in a Flask Application?

Passing Variables Between Flask Pages

In Flask applications, it may be necessary to share data between different pages. To achieve this, there are several approaches available.

Session Variables

If you need to store data that is not user-visible and can be safely serialized as JSON, the Flask session can be employed. This approach is suitable for smaller amounts of data, as excessive size can lead to performance issues.

@app.route('/a')
def a():
    # Store a variable in the session
    session['my_var'] = 'my_value'
    
    # Redirect to page b
    return redirect(url_for('b'))

@app.route('/b')
def b():
    # Retrieve the variable from the session
    my_var = session.get('my_var', None)
    
    return my_var

Query Parameters

For passing data from a template to a URL, query parameters can be utilized. They allow you to append data to the URL in a format like:

/b?my_var=my_value

This approach is convenient for smaller amounts of data that are visible to the user. The data can be accessed in the receiving page.

@app.route('/b')
def b():
    # Retrieve the variable from the query parameters
    my_var = request.args.get('my_var', None)

Other Considerations

When storing large amounts of data, consider using a database or external data storage instead of session variables. This ensures optimal performance and security. Additionally, using session variables for user-visible data may not be advisable, as cookies and session data can be manipulated by users.

The above is the detailed content of How to Effectively Pass Variables Between Pages in a Flask Application?. For more information, please follow other related articles on the PHP Chinese website!