SQLAlchemy error "on delete" - database

Question

i´m new to Flask and i´m trying to delete a user.
I can already create a user, it is saying that 1 argument is missing:
add_user.html
<form method="POST" action="/del_user">
<label> ID: </label>
<input id="id" name ="id" type="text" />
<input type="submit" value="Delete"/>
</form>
app.py
from flask import Flask, render_template, request, redirect, url_for
from flask_sqlalchemy import SQLAlchemy
app = Flask(__name__)
#Set the application in debug mode so that the server is reloaded on any code change & helps debug
app.config['DEBUG'] = True
app.config['SQLALCHEMY_DATABASE_URI'] = 'postgresql://postgres:********#localhost/projetofinal'
db = SQLAlchemy(app)
class User(db.Model):
id = db.Column(db.Integer, primary_key=True)
username = db.Column(db.String(80), unique=True)
email = db.Column(db.String(120), unique=True)
def __init__(self, username, email):
self.username = username
self.email = email
def __repr__(self):
return '<User %r>' % self.username
#app.route('/')
def index():
return render_template('add_user.html')
#app.route('/post_user', methods=['POST'])
def post_user():
user = User(request.form['username'], request.form['email'])
db.session.add(user) #add object
db.session.commit() #save
return redirect(url_for('index'))
#app.route('/del_user', methods=['POST'])
def del_user():
user = User(request.form['id']) #ERROR LINE
user1 = db.session.query(User).filter(User.id==user.id).first()
db.session.delete(user1)
db.session.commit()
return redirect(url_for('index'))
if __name__=="__main__":
app.run()
TypeError: init() missing 1 required positional argument: 'email'

Answer 1

Just get the id from the form, turn it into an integer and query the database for it.
#app.route('/del_user', methods=['POST'])
def del_user():
user = int(request.form['id'])
user1 = db.session.query(User).filter(User.id==user.id).first()
db.session.delete(user1)
db.session.commit()
return redirect(url_for('index'))
Additionally check if your db query returns a user object to make sure you don't attempt to delete a non existent user and get another error
if user1:
db.session.delete(user1)
else:
flash('the record requested was not found')
return redirect(url_for('index'))
see how to use flash here to show error messages etc elegantly
Lastly, Instead of deleting using text input, you can use select that uses already existing users so that the value is the user id and the option text is the user name to make sure attempt to delete only uses existing user ids