Flask: AttributeError: 'UnboundField' Objekt hat kein Attribut '__call__'?

Question

Warum bekomme ich diesen Fehler? Was ist das UnboundField und was muss ich wissen, um dieses Problem in Zukunft zu beheben und zu vermeiden?

Debug-Ausgabe, wenn ich Besuch http://127.0.0.1:5000/signup:

AttributeError 

AttributeError: 'UnboundField' object has no attribute '__call__' 
Traceback (most recent call last) 

    File "C:\Users\combatmath\Envs\default\lib\site-packages\flask\app.py", line 2000, in __call__ 

    return self.wsgi_app(environ, start_response) 

    File "C:\Users\combatmath\Envs\default\lib\site-packages\flask\app.py", line 1991, in wsgi_app 

    response = self.make_response(self.handle_exception(e)) 

    File "C:\Users\combatmath\Envs\default\lib\site-packages\flask\app.py", line 1567, in handle_exception 

    reraise(exc_type, exc_value, tb) 

    File "C:\Users\combatmath\Envs\default\lib\site-packages\flask\app.py", line 1988, in wsgi_app 

    response = self.full_dispatch_request() 

    File "C:\Users\combatmath\Envs\default\lib\site-packages\flask\app.py", line 1641, in full_dispatch_request 

    rv = self.handle_user_exception(e) 

    File "C:\Users\combatmath\Envs\default\lib\site-packages\flask\app.py", line 1544, in handle_user_exception 

    reraise(exc_type, exc_value, tb) 

    File "C:\Users\combatmath\Envs\default\lib\site-packages\flask\app.py", line 1639, in full_dispatch_request 

    rv = self.dispatch_request() 

    File "C:\Users\combatmath\Envs\default\lib\site-packages\flask\app.py", line 1625, in dispatch_request 

    return self.view_functions[rule.endpoint](**req.view_args) 

    File "C:\Users\combatmath\Apps\ocrbox\routes.py", line 27, in signup 

    return render_template("signup.html", form=form) 

    File "C:\Users\combatmath\Envs\default\lib\site-packages\flask\templating.py", line 134, in render_template 

    context, ctx.app) 

    File "C:\Users\combatmath\Envs\default\lib\site-packages\flask\templating.py", line 116, in _render 

    rv = template.render(context) 

    File "C:\Users\combatmath\Envs\default\lib\site-packages\jinja2\environment.py", line 989, in render 

    return self.environment.handle_exception(exc_info, True) 

    File "C:\Users\combatmath\Envs\default\lib\site-packages\jinja2\environment.py", line 754, in handle_exception 

    reraise(exc_type, exc_value, tb) 

    File "C:\Users\combatmath\Apps\ocrbox\templates\signup.html", line 1, in top-level template code 

    {% extends "base.html" %} 

    File "C:\Users\combatmath\Apps\ocrbox\templates\base.html", line 9, in top-level template code 

    {% block content %}{% endblock %} 

    File "C:\Users\combatmath\Apps\ocrbox\templates\signup.html", line 30, in block "content" 

    {{ form.submit(class="btn-primary") }} 

    AttributeError: 'UnboundField' object has no attribute '__call__' 

signup.html:

{% extends "base.html" %} 

{% block title %}Join ocrbox!{% endblock %} 

{% block content %} 
    <main class="container signup-section"> 
     <div class="section-content"> 
      <h2>Create an account</h2> 

      <form method="POST" action="/signup"> 


       <div class="form-group"> 
        {{ form.first_name.label }} 
        {{ form.first_name }} 
       </div> 
       <div class="form-group"> 
        {{ form.last_name.label }} 
        {{ form.last_name }} 
       </div> 
       <div class="form-group"> 
        {{ form.email.label }} 
        {{ form.email }} 
       </div> 
       <div class="form-group"> 
        {{ form.password.label }} 
        {{ form.password }} 
       </div> 

       {{ form.submit(class="btn-primary") }} 
      </form> 
     </div> 
    </main> 
{% endblock %} 

routes.py:

from flask import Flask, render_template, request 
from models import db 
from forms import SignupForm 

app = Flask(__name__) 

app.config['SQLALCHEMY_DATABASE_URI'] = 'postgresql://localhost/ocrbox' 
db.init_app(app) 

app.secret_key = "development-key" 

@app.route("/") 
def index(): 
    return render_template("index.html") 

@app.route("/about") 
def about(): 
    return render_template("about.html") 

@app.route("/signup", methods=['GET', 'POST']) 
def signup(): 
    form = SignupForm 

    if request.method == 'POST': 
     return "Success!" 
    elif request.method == 'GET': 
     return render_template("signup.html", form=form) 

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

forms.py:

from flask_wtf import Form 
from wtforms import StringField, PasswordField, SubmitField 

class SignupForm(Form): 
    first_name = StringField('First name') 
    last_name = StringField('Last name') 
    email = StringField('Email') 
    password = PasswordField('Password') 
    submit = SubmitField('Sign up') 

models.py:

from flask_sqlalchemy import SQLAlchemy 
from werkzeug import generate_password_hash, check_password_hash 

db = SQLAlchemy() 

class User(db.Model): 
    __tablename__ = 'users' 
    uid = db.Column(db.Integer, primary_key=True) 
    firstname = db.Column(db.String(100)) 
    lastname = db.Column(db.String(100)) 
    email = db.Column(db.String(120), unique=True) 
    pwdhash = db.Column(db.String(54)) 

    def __init__(self, firstname, lastname, email, password): 
     self.firstname = firstname.title() 
     self.lastname = lastname.title() 
     self.email = email.lower() 
     self.set_password(password) 

    def set_password(self, password): 
     self.pwdhash = generate_password_hash(password) 

    def check_password(self, password): 
     return check_password_hash(self.pwdhash, password) 

Answer 1

In routes.py, ich glaube, Ihre signup() Methode form = SignupForm(request.form) enthalten sollte. Andernfalls wird das Formular auf eine Klasse anstelle einer Instanz festgelegt.