Problems with the "validate_on_submit()" function (I think...)

from flask import Flask, g, render_template, flash, redirect, url_for
from flask_bcrypt import check_password_hash
from flask_login import (LoginManager, login_user, logout_user,
                            login_required, current_user)

import forms
import models


DEBUG = True
PORT = 8000
HOST = '127.0.0.1'

app = Flask(__name__)
app.secret_key = 'isbfF74tG75 HbgX-<x9et*b/.hbbuh#-@ib5G'

login_manager = LoginManager()
login_manager.init_app(app)
login_manager.login_view = 'login'


@login_manager.user_loader
def load_user(userid):
    try:
        return models.User.get(models.User.id == userid)
    except models.DoesNotExist:
        return None


@app.before_request
def before_request():
    """Connect to the database before each request.
    """
    g.db = models.DATABASE
    g.db.connect()
    g.user = current_user


@app.after_request
def after_request(response):
    """Close the database connection after each request.
    """
    g.db.close()
    return response


# Doesn't work
@app.route('/register', methods = ('GET', 'POST'))
def register():
    form = forms.RegistarationForm()
    if form.validate_on_submit():
        flash("Registration successful!", "success")
        models.User.create_user(
            username = form.username.data,
            email = form.email.data,
            password = form.password.data
        )
        return redirect(url_for('index'))
    return render_template('register.html', form = form)


@app.route('/login', methods = ('GET', 'POST'))
def login():
    form = forms.LoginForm()
    if form.validate_on_submit():
        try:
            user = models.User.get(models.User.email == form.email.data)
        except models.DoesNotExist:
            flash("The email and password you've entered don't match." , "error")
        else:
            if check_password_hash(user.password, form.password.data):
                login_user(user)
                flash("You've been logged in successfully.", "success")
                return redirect(url_for('index'))
            else:
                flash("The email and password you've entered don't match." , "error")
    return render_template('login.html', form = form)


@app.route('/logout')
@login_required
def logout():
    logout_user()
    flash("You've been logged out.", "success")
    return redirect(url_for('index'))


# Doesn't work
@app.route('/new_post', methods = ('GET', 'POST'))
@login_required
def post():
    post = forms.PostForm()
    if post.validate_on_submit():
        models.Post.create(
            user = g.user._get_current_object(),
            content = post.content.data.strip()
        )
        flash("Message posted successfully!", "success")
        return redirect(url_for('index'))
    return render_template('post.html', form = post)


@app.route('/stream')
@app.route('/stream/<username>')
def stream(username = None):
    template = 'stream.html'
    if username and username != current_user.username:
        user = models.User.select().where(models.User.username ** username).get()
        stream = user.posts.limit(100)
    else:
        user = current_user
        stream = current_user.get_stream().limit(100)
    if username:
        template = 'user_stream.html'
    return render_template(template, stream = stream, user = user)


@app.route('/')
def index():
    stream = models.Post.select().limit(100)
    return render_template('stream.html', stream = stream)


if __name__ == '__main__':
    models.initialize()
    try:
        models.User.create_user(
            username = 'superuser',
            email = 'superuser@gmail.com',
            password = 'password',
            is_admin = True
        )
    except ValueError:
        pass
    app.run(debug = DEBUG, port = PORT, host = HOST)