How can I validate data in Flask using ORM?

How can I validate data in Flask using ORM?

You can use Flask-WTF for form validation along with SQLAlchemy for ORM. Would you like a code example?

Yes, please provide a code example for validating a user registration form.

Sure! Here's a simple example:

from flask import Flask, render_template, redirect, url_for
from flask_wtf import FlaskForm
from wtforms import StringField, PasswordField, SubmitField
from wtforms.validators import DataRequired, Email, Length

class RegistrationForm(FlaskForm):
    username = StringField('Username', validators=[DataRequired(), Length(min=2, max=20)])
    email = StringField('Email', validators=[DataRequired(), Email()])
    password = PasswordField('Password', validators=[DataRequired()])
    submit = SubmitField('Sign Up')

# In your route, you can validate the form like this:

@app.route('/register', methods=['GET', 'POST'])
def register():
    form = RegistrationForm()
    if form.validate_on_submit():
        # Process the data
        return redirect(url_for('home'))
    return render_template('register.html', form=form)

What if I want to add custom validation?

You can create custom validators by defining a function and using it in your form field. Would you like an example?