forms.py


from flask_wtf import FlaskForm
from wtforms.fields import EmailField
from wtforms.validators import DataRequired, Length


class EmptyForm(FlaskForm):
    pass

class EmailForm(FlaskForm):

    email = EmailField('Email', validators=
    [
    DataRequired('Email is required'),
    # Is the line below useful
    Length(min=4, max=25, message='Must be between 4 and 25 characters'),
    ])



functions.py




from flask import flash
from app import db


def add_foreign_key(email_form):
    '''
    This runs in the /donation route.
    if the email exists in the User table and the email exists in the Payment table exists add the FK.
    The function only works if you are making a donation with an User who has an account.
    You will always have a registered account when adding Foreign key.
    '''

    # makes sure the tables are not (None / empty) list + contain same emails in the db
    if db.session.execute(db.select(User).filter_by(email=email_form)).scalar_one_or_none() and \
       db.session.execute(db.select(Payments).filter_by(email=email_form)).scalar_one_or_none():

        user_db = db.session.execute(db.select(User).filter_by(email=email_form)).scalar_one_or_none()
        payment_db = db.session.execute(db.select(Payments).filter_by(email=email_form)).scalar_one_or_none()

        if user_db.email == payment_db.email:
            user_id_db = user_db.id
            payment_db.fk_user_id = user_id_db
            db.session.commit()
            flash('Success the Foreign key is added')
            return 'success'
    # executes if the "if" statements doesn't activate?
    print('The Foreign key is not added')