FLASK PYTHON：TypeError：“int”类型的 object 没有 len()

Question

I am trying to make an upload form with Flask where the user needs to fill in the information needed, upload a photo, and also to pick a category provided from the database by using QuerySelectField.

When I submit the form, I get TypeError: object of type 'int' has no len().

The goal was to have different events of various types. Like cafes, Restaurants, etc. I think the problem is at if formupload.validate_on_submit():

The Error

> Traceback (most recent call last):
  File "/Users/abc/.conda/envs/file/lib/python2.7/site-packages/flask/app.py", line 2464, in __call__
    return self.wsgi_app(environ, start_response)
  File "/Users/abc/.conda/envs/file/lib/python2.7/site-packages/flask/app.py", line 2450, in wsgi_app
    response = self.handle_exception(e)
  File "/Users/abc/.conda/envs/file/lib/python2.7/site-packages/flask/app.py", line 1867, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/Users/abc/.conda/envs/file/lib/python2.7/site-packages/flask/app.py", line 2447, in wsgi_app
    response = self.full_dispatch_request()
  File "/Users/abc/.conda/envs/file/lib/python2.7/site-packages/flask/app.py", line 1952, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/Users/abc/.conda/envs/file/lib/python2.7/site-packages/flask/app.py", line 1821, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/Users/abc/.conda/envs/file/lib/python2.7/site-packages/flask/app.py", line 1950, in full_dispatch_request
    rv = self.dispatch_request()
  File "/Users/abc/.conda/envs/file/lib/python2.7/site-packages/flask/app.py", line 1936, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/Users/abc/.conda/envs/file/lib/python2.7/site-packages/flask_login/utils.py", line 272, in decorated_view
    return func(*args, **kwargs)
  File "/Users/abc/PythonProjects/file/website/routes.py", line 150, in post_events
    if formupload.validate_on_submit():
  File "/Users/abc/.conda/envs/file/lib/python2.7/site-packages/flask_wtf/form.py", line 100, in validate_on_submit
    return self.is_submitted() and self.validate()
  File "/Users/abc/.conda/envs/file/lib/python2.7/site-packages/wtforms/form.py", line 318, in validate
    return super(Form, self).validate(extra)
  File "/Users/abc/.conda/envs/file/lib/python2.7/site-packages/wtforms/form.py", line 150, in validate
    if not field.validate(self, extra):
  File "/Users/abc/.conda/envs/file/lib/python2.7/site-packages/wtforms/fields/core.py", line 226, in validate
    stop_validation = self._run_validation_chain(form, chain)
  File "/Users/abc/.conda/envs/file/lib/python2.7/site-packages/wtforms/fields/core.py", line 246, in _run_validation_chain
    validator(form, self)
  File "/Users/abc/.conda/envs/file/lib/python2.7/site-packages/wtforms/validators.py", line 104, in __call__
    l = field.data and len(field.data) or 0
TypeError: object of type 'int' has no len()

form.py

class UploadForm(FlaskForm):
title = StringField(label='Title:', validators=[DataRequired(), Length(min=2, max=30)])
organizer = StringField(label='Name:', validators=[DataRequired(), Length(min=2, max=30)],
                        render_kw={'readonly': True})
type = QuerySelectField(query_factory=choice_query, allow_blank=False, get_label='name')
description = StringField(label='description',validators=[DataRequired(), Length(min=1, max=250)])
address = StringField(label='address',validators=[DataRequired(), Length(min=1, max=50)])
file = FileField(label='file', validators=[DataRequired()])
price = IntegerField(label='Price:',validators=[DataRequired(),Length(min=1, max=10)])
upload = SubmitField(label='Post')

model.py

class Event(db.Model):
__tablename__ = "event"
id = db.Column(db.Integer, primary_key=True)
title = db.Column(db.String(30), nullable=False)
price = db.Column(db.Integer(), nullable=False)
location = db.Column(db.String(50), nullable=False)
description = db.Column(db.String(1024), nullable=True, unique=True)
date_posted = db.Column(db.DateTime, nullable=False, default=datetime.utcnow)
type = db.Column(db.Integer(), db.ForeignKey('category.id'), nullable=False)
image_file = db.Column(db.String(20), nullable=True, default='default.jpg')
owner = db.Column(db.Integer(), db.ForeignKey('eventowners.id'), nullable=False)
reserver = db.relationship('Reservation', foreign_keys=[Reservation.reserved_id],
                           backref=db.backref('reserved', lazy='joined'), lazy='dynamic',
                           cascade='all, delete-orphan')



class Choice(db.Model):
__tablename__ = "category"
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(20), nullable=False)
event = db.relationship('Event', backref='events', lazy=True)

def __repr__(self):
    return '[Choice {}]'.format(self.name)

class EventOwner(db.Model, UserMixin, USER):
__tablename__ = 'eventowners'
role_id = db.Column(db.Integer, db.ForeignKey('roles.id'))
sub_type = db.Column(db.String, nullable=True, default=00)
events = db.relationship('Event', backref='eventowner', lazy=True)
follower = db.relationship('Follow', foreign_keys=[Follow.followed_id],
                           backref=db.backref('followed', lazy='joined'), lazy='dynamic',
                           cascade='all, delete-orphan')

routes.py

@app.route('/event/new', methods=['GET', 'POST'])
@login_required
def post_events():
    if not os.path.exists('static/' + str(session.get('id'))):
       os.makedirs('static/' + str(session.get('id')))
    file_url = os.listdir('static/' + str(session.get('id')))
    file_url = [str(session.get('id')) + "/" +
                 file for file in file_url]
    formupload = UploadForm()
    eventowner = current_user.id
    formupload.organizer.data = eventowner
    event = Event(owner=formupload.organizer.data)
    if formupload.validate_on_submit():
       event = Event(title=formupload.title.data,
                  type=formupload.type.data,
                  description=formupload.description.data,
                  price=formupload.price.data,
                  location=formupload.address.data,
                  image_file=photos.save(formupload.file.data,
                                         name=str(session.get('id')) + '.jpg',))

      db.session.add(event)
      db.session.commit()
      flash('Event Posted!')
      return redirect(url_for('events_page'))
    return render_template('post_event.html', formupload=formupload, event=event)

Some parts of post_event.html

<div class="form-group col-md-4">
  <label for="inputState" style="color: black" >Type</label>
      {{ formupload.csrf_token }}
      {{ formupload.type }}
      <ul>
        {% for error in formupload.type.errors %}
        <li style="color:red;">{{ error }}</li>
        {% endfor %}
      </ul>
</div>
<div class="form-group col-md-6">
  <label for="description" style="color: black" >Description</label>
  {{ formupload.label }} {{ formupload.description(class='form-control' )}}
</div>
<div class="form-group col-md-6">
  <label for="starting_price" style="color: black" >Starting Price</label>
  {{ formupload.label }} {{ formupload.price(class='form-control' )}}
</div>
  <div class="form-group">
    <label for="inputAddress2" style="color: black" >Address</label>
    {{ formupload.label }} {{ formupload.address(class='form-control' )}}
 </div>
<div class="form-group">
   <div class="form-check">
     <input class="form-check-input" type="checkbox" id="gridCheck">
     <label class="form-check-label" for="gridCheck" style="color: black">
      I agree to the Terms of Service and Privacy Policy
      </label>
    </div>
</div>
<div class="form-group">
    {{ formupload.file.label }}
    {{ formupload.file }}
    {{ formupload.upload }}
    {% for file in filelist %}
        <img class="upload-img"  src='{{ url_for("static",filename=file) }}' alt="">
    {% endfor %}
</div>

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

Answer 1

The problem might be from the fields in your model. You have to use NumberRange for IntergerField instead of using Length which is for a string

Please try

price = IntegerField(label='Price:', validators=[DataRequired(), NumberRange(min=1, max=10)])

• https://wtforms.readthedocs.io/en/3.0.x/validators/?highlight=numberrange#wtforms.validators.NumberRange