LOGIN FORM FLASK FAILS

I have a RegisterForm and LoginForm made with Flask and hashed with sha256. The RegisterForm works, but the login page is not returning anything. I stay in the same login page, the only difference is the url returns this:

HTTP/1.1[0m" 304 -INFO:werkzeug:127.0.0.1 - - [27/Nov/2021 04:56:29]
"GET /?username=alex29&password=12345&submit=Login HTTP/1.1" 200 -

And the url change to this:

http://localhost:5000/?username=alex29&password=12345&submit=Login

from flask import Flask, render_template, url_for, redirect, session, flash, request
from flask_sqlalchemy import SQLAlchemy
from flask_login import UserMixin, login_user, LoginManager, login_required, logout_user, current_user
from flask_wtf import FlaskForm
from wtforms import StringField, PasswordField, SubmitField
from wtforms.validators import InputRequired, Length, ValidationError
from flask_bcrypt import Bcrypt
from werkzeug.security import generate_password_hash, check_password_hash
from flask_wtf.csrf import CSRFProtect
from werkzeug.urls import url_parse
import sqlite3

app = Flask (__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///gestdoc.db'
app.config['SECRET_KEY'] = 'thisisasecretkey'
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
db = SQLAlchemy(app)
USER_LOGIN_URL = '/login'
USER_ENABLE_USERNAME = True

csrf = CSRFProtect(app)

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


@login_manager.user_loader
def load_user(id_user):
    return User.query.get(int(id_user))

class User(db.Model, UserMixin):
    id_user = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(20), nullable=False, unique=True)
    password = db.Column(db.String(80), nullable=False)
    authenticated = db.Column(db.Boolean, default=False)

    def set_password(self, password):
        self.password = generate_password_hash(password)
    
    def check_password(self, password):
        return check_password_hash(self.password, password)

    def is_active(self):
        return True

    def is_authenticated(self):      
        return True

    def is_anonymous(self):        
        return True

class employee(db.Model):
    id_employee = db.Column(db.CHAR(100), primary_key=True)
    name = db.Column(db.TEXT(100), nullable=False)
    surname = db.Column(db.TEXT(100), nullable=False)

class RegisterForm(FlaskForm):
    username = StringField(validators=[InputRequired(), Length(min=4, max=20)], render_kw={"placeholder": "Usuario"})
    password = PasswordField(validators=[InputRequired(), Length(min=4, max=20)], render_kw={"placeholder": "Contraseña"})
    submit = SubmitField("Register")

    def validate_username(self, username):
         user = User.query.filter_by(username=username.data).first()
         if user is not None:
            raise ValidationError('Este usuario ya existe. Use otro.')

class EmployeeForm(FlaskForm):
    id_employee = StringField(validators=[InputRequired(), Length(min=4, max=20)], render_kw={"placeholder": "DNI"})
    name = StringField(validators=[InputRequired(), Length(min=4, max=20)], render_kw={"placeholder": "NOMBRE"})
    surname = StringField(validators=[InputRequired(), Length(min=4, max=20)], render_kw={"placeholder": "APELLIDOS"})
    submit = SubmitField("Guardar")

    def validate_employee(self, employee):
        check_id_employee = User.query.filter_by(employee=id_employee.data).first()
        if check_id_employee:
            raise ValidationError('Este empleado ya existe.')

class LoginForm(FlaskForm):
    username = StringField(validators=[InputRequired(), Length(min=4, max=20)], render_kw={"placeholder": "Username"})
    password = PasswordField(validators=[InputRequired(), Length(min=4, max=20)], render_kw={"placeholder": "Password"})
    submit = SubmitField('Login')            

@app.route('/', methods=['GET','POST'])
def login():
    form = LoginForm(meta={'csrf': False})
    if form.validate_on_submit():
        user = User.query.filter_by(username=form.username.data).first()
        if user: 
            if check_password(user.password, form.password.data):
                login_user(user)
                flash("Log In")
                return redirect(url_for('admin'))
            else:
                flash('Invalid password')

        else:
            flash('usuario no existe')   
     
    return render_template('login.html', form=form)

@app.route('/admin', methods=['GET','POST'])
@login_required
def showemployee():
    con = sqlite3.connect('gestdoc.db')
    cur = con.cursor()
    cur.execute('SELECT * from employee')
    employee = cur.fetchall()
    con.close()
    return render_template('admin.html', employee=employee)

@app.route('/register', methods=['GET','POST'])
def register():
    form = RegisterForm()
    if form.validate_on_submit():           
        user = User(username=form.username.data)
        user.set_password(form.password.data)
        db.session.add(user)
        db.session.commit()
        flash('Usuario registrado')
        return redirect(url_for('login')) 

    return render_template('register.html', form=form)


import logging              
logging.basicConfig(filename = "sample.log", level = logging.DEBUG,filemode = "w+" )
logging.debug('debug')
logging.info('info')
logging.warning('warning')
logging.error('error')
logging.critical('critical')



if __name__ == '__main__':
    app.run(debug=True)

Thank you for the help

Answer

I think you forgot to change the login form method to “post”

source

Here you can find an example of how to set the needed form attributes.

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Answer