@app.route('/login', methods=['GET','POST'])
def login():
    if session.get('zalogowany'):
        username = str(request.form['username'])
        usertoShow = User.query.filter_by(username=username).first()
        return render_template('login.html', user_show=usertoShow)
    else:
        request.method == 'POST'
        username = str(request.form['username'])
        usertoShow = User.query.filter_by(username=username).first()
        password = str(request.form['password'])
        result = User.query.filter_by(username=username,password=password).first()
        if result:
            session['zalogowany'] = True
            session['user_id'] = result.id
        else:
            flash(Markup('<p><font color="red">Zly login lub haslo.<br>Chcialbys sie </font><a href="/register">zarejestrowac?</a></p>'))
        return render_template('login.html', user_show = usertoShow)