Ошибка sqlite: NOT NULL constraint failed

from datetime import date
from app import db
 
 
class Post(db.Model):
    id = db.Column(db.Integer, primary_key=True, autoincrement=True)
    article = db.Column(db.String(100), unique=True, nullable=False)
    text= db.Column(db.String(3000), unique=False, nullable=False)
    created_date =db.Column(db.Date, default=date.today)
 
class Comments(db.Model):
    id = db.Column(db.Integer, primary_key=True, autoincrement=True)
    post_id = db.Column(
        db.Integer,
        db.ForeignKey('post.id'),
        nullable=False,
        index=True,
        )
    posts = db.relationship(Post, foreign_keys=[post_id, ])
    comm = db.Column(db.String(80), unique=True, nullable=False)
    comm_created_date =db.Column(db.Date, default=date.today)

from flask import Flask, request, render_template, flash
from flask_sqlalchemy import SQLAlchemy
import config as config
 
app = Flask(__name__, template_folder='templates')
app.config.from_object(config)
 
db = SQLAlchemy(app)
 
@app.route('/', methods=['GET', 'POST'])
def index():
    from models import Post, Comments
    from form import PostForm, CommentsForm
 
    if request.method == 'POST':
        print(request.form)
        form = PostForm(request.form)
        comments_form = CommentsForm(request.form)
 
        if form.validate():
            post = Post(**form.data)
            db.session.add(post)
            db.session.commit()
            flash('Post created!')
        elif comments_form.validate():
            comm = Comments(**comments_form.data)
            db.session.add(comm)
            db.session.commit() 
            flash('Comms created!')
        else:
            flash('Form is not valid! Post was not created.')
            flash(str(form.errors))
    posts = Post.query.all()
    comms = Comments.query.all()
    return render_template('basic_template.txt', posts = posts, comms=comms)
 
if __name__ == '__main__':
    from models import *
 
    db.create_all()
    app.run()