Time to tackle groups of users! But what's the best approach?

Do you have overlap between the Users and the Instructors, or are they distinct? If someone is a student in one class and an instructor in another, it might be easier to have one table for basic user information in addition to the User and Instructor tables, with a foreign key to link the tables, so that when information like name or email addresses are updated, they only need to be updated once and not once for each table. If no one is both a student and an instructor, having two distinct tables with different information stored in them seems reasonable.

Instead of

        try:
            user = models.User.get(models.User.email == form.email.data) or \
                models.Instructor.get(models.Instructor.email == form.email.data)
        except models.DoesNotExist:
            flash("There was a problem", "error")

which will throw an exception if the email does not match a User's email, you might want something like

        try:
            user = models.User.select().where(models.User.email == form.email.data).first() or \
                models.Instructor.select().where(models.Instructor.email == form.email.data).first()
            if not user:
                raise models.DoesNotExist
        except models.DoesNotExist:
            flash("There was a problem", "error")

models.User.get(models.User.email == form.email.data) is similar to models.User.select().where(models.User.email == form.email.data), but while .get() returns a single row for the result set or throws an exception if no results are found, .select().where() returns all the qualifying rows in its result set with a possible empty result set. Assuming that emails are unique, you can use .first() to get only the first row in the result set or None if the email was not found. You can then raise an exception if user is None.

In the line if (user.is_admin == 1):, what does 1 mean? If user.is_admin is a boolean, you could replace the if statement with if user.is_admin:.

In the line elif (models.Instructor.email == form.email.data):, models.Instructor.email is probably something like <CharField: Instructor.email> rather than an email address. You could replace the condition with models.Instructor.select().where(models.Instructor.email == form.email.data).first() to determine if the email from the form matches an instructor's email, which would be repeating code from the try block. You could also consider setting a variable in the try block to keep track of if the email was for an instructor, such as

        try:
            is_instructor = models.Instructor.select().where(models.Instructor.email == form.email.data).first()
            user = models.User.select().where(models.User.email == form.email.data).first() or is_instructor  
            if not user:
                raise models.DoesNotExist
        except models.DoesNotExist:
            flash("There was a problem", "error")

then using elif is_instructor:.

jb30 - Having looked at the docs and scoured stackoverflow, I think I see a challenge of using flask-login. According to the docs, the way to allow for multiple types of users is with 'roles'. So you have one User class that has a column for 'role' and within that, you define a tuple that is along the lines of ('role', 'need'). A bit confusing here but essentially 'role' would actually be just that a role. The need is then what kind of role i.e. 'User', 'Instructor' or 'admin'.

With the above in mind, the 'login_user(user)' would then still just login the user (because they are part of the user table)) and you would then have a function that uses the role to apply permissions for access to different information.

The problem with the existing structure of code is the 'login_user(user)'. There is no way I can see at the moment to tell flask-login that 'user' could also be an instructor.

Interested in your thoughts. Does the above sound correct, or do you think it's still possible to do a single login whilst still using flask-login?

Loving the challenge, but I fear I am confusing myself further each day! :P

jb30 - So in between me writing and you answering (thank you as always, I owe you a drink!), I decided to go with the single User model. I will have all users in the same table with a role column.

I've tested it and know that the user registration works and populates all the fields correctly. When the user tries to log-in, it allows them to but I now have the same problem I originally had; how do I identify the user logging in against the role in the User table and then send them to the right profile page. My thinking is something along these lines:

''' login users '''
@app.route('/login', methods=('GET', 'POST'))
def login():
    form = forms.LoginForm()
    if form.validate_on_submit():
        try:
            user = models.User.select().where(models.User.email == form.email.data).first()
            if not user:
                raise models.DoesNotExist
        except models.DoesNotExist:
            flash("There was a problem", "error")
        else:
            if check_password_hash(user.password, form.password.data):
                login_user(user)
                if user.is_admin:
                    return redirect(url_for('admin'))
                elif models.User.role == 'instructor':
                    return redirect(url_for('instructor_profile'))
                else:
                    flash("You've been logged in!", "success")
                return redirect(url_for('profile'))
            else:
                flash("Your email or password doesn't match!", "error")
    return render_template('login.html', form=form)

In my logic, I think the above code should catch any user and log them in. What it should then do is check if they are admin (redirect to admin page), if not, it then checks for the users role (redirects them to instructor profile), else it redirects to user profile.

It's the Instructor part that feels wrong to me. I guess models.User.role == 'instructor' doesn't know which user we're talking about? Maybe after selecting the user through their email, I check for the role in try block and store that in a variable?

jb30 - Sometimes, it's the simplest and most frustrating thing!! I tried your code above, which makes sense now as user is declared earlier in the function so it's already referencing the user table. But it still didn't work!

Everything kept redirecting back to the same profile page regardless of the role! I then wondered if it might be a problem with the column itself (maybe I named it differently or something). I checked the column and realised that the data being passed to the table is Instructor and not instructor as per my function. Once I changed that, with your last comment above, it worked just as expected.

Thanks again. The conversation and working through the logic of your answers has really helped my understanding!

I owe ya! :)