How to override model creation form?

Hi, I’d like to override flask-admin’s model creation form. So I override form object like below.

from wtforms import PasswordField, StringField, form, Form
from wtforms.validators import DataRequired, Length, EqualTo
from wtforms.ext.sqlalchemy.fields import QuerySelectField
from flask.ext.admin.contrib.sqla import ModelView

class ShopOwnerForm(form.Form):
    name = StringField(
        'Username',
        validators=[
            DataRequired(),
            Length(max=128),
        ],
    )
    shop = QuerySelectField(
        'Shop Name',
        query_factory=Shop.query.all,
        get_pk=attrgetter('id'),
        get_label=attrgetter('name'),
    )

class ShopOwnerAdmin(ModelView):
    form = ShopOwnerForm

But, sqlalchemy.exc.InvalidRequestError has occured at following point.

https://github.com/flask-admin/flask-admin/blob/master/flask_admin/contrib/sqla/view.py#L1014

This is the error message .

Traceback (most recent call last):
  File "/Users/zakuro/src/gitlab.com/akashipy/guji_delivery/venv/lib/python3.5/site-packages/flask/app.py", line 1836, in __call__
    return self.wsgi_app(environ, start_response)
  File "/Users/zakuro/src/gitlab.com/akashipy/guji_delivery/venv/lib/python3.5/site-packages/flask/app.py", line 1820, in wsgi_app
    response = self.make_response(self.handle_exception(e))
  File "/Users/zakuro/src/gitlab.com/akashipy/guji_delivery/venv/lib/python3.5/site-packages/flask/app.py", line 1403, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/Users/zakuro/src/gitlab.com/akashipy/guji_delivery/venv/lib/python3.5/site-packages/flask/_compat.py", line 33, in reraise
    raise value
  File "/Users/zakuro/src/gitlab.com/akashipy/guji_delivery/venv/lib/python3.5/site-packages/flask/app.py", line 1817, in wsgi_app
    response = self.full_dispatch_request()
  File "/Users/zakuro/src/gitlab.com/akashipy/guji_delivery/venv/lib/python3.5/site-packages/flask/app.py", line 1477, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/Users/zakuro/src/gitlab.com/akashipy/guji_delivery/venv/lib/python3.5/site-packages/flask/app.py", line 1381, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/Users/zakuro/src/gitlab.com/akashipy/guji_delivery/venv/lib/python3.5/site-packages/flask/_compat.py", line 33, in reraise
    raise value
  File "/Users/zakuro/src/gitlab.com/akashipy/guji_delivery/venv/lib/python3.5/site-packages/flask/app.py", line 1475, in full_dispatch_request
    rv = self.dispatch_request()
  File "/Users/zakuro/src/gitlab.com/akashipy/guji_delivery/venv/lib/python3.5/site-packages/flask/app.py", line 1461, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/Users/zakuro/src/gitlab.com/akashipy/guji_delivery/venv/lib/python3.5/site-packages/flask_admin/base.py", line 68, in inner
    return self._run_view(f, *args, **kwargs)
  File "/Users/zakuro/src/gitlab.com/akashipy/guji_delivery/venv/lib/python3.5/site-packages/flask_admin/base.py", line 367, in _run_view
    return fn(self, *args, **kwargs)
  File "/Users/zakuro/src/gitlab.com/akashipy/guji_delivery/venv/lib/python3.5/site-packages/flask_admin/model/base.py", line 1834, in create_view
    model = self.create_model(form)
  File "/Users/zakuro/src/gitlab.com/akashipy/guji_delivery/venv/lib/python3.5/site-packages/flask_admin/contrib/sqla/view.py", line 1031, in create_model
    if not self.handle_view_exception(ex):
  File "/Users/zakuro/src/gitlab.com/akashipy/guji_delivery/venv/lib/python3.5/site-packages/flask_admin/contrib/sqla/view.py", line 1014, in handle_view_exception
    return super(ModelView, self).handle_view_exception(exc)
  File "/Users/zakuro/src/gitlab.com/akashipy/guji_delivery/venv/lib/python3.5/site-packages/flask_admin/contrib/sqla/view.py", line 1027, in create_model
    self.session.add(model)
  File "/Users/zakuro/src/gitlab.com/akashipy/guji_delivery/venv/lib/python3.5/site-packages/sqlalchemy/orm/scoping.py", line 150, in do
    return getattr(self.registry(), name)(*args, **kwargs)
  File "/Users/zakuro/src/gitlab.com/akashipy/guji_delivery/venv/lib/python3.5/site-packages/sqlalchemy/orm/session.py", line 1600, in add
    self._save_or_update_state(state)
  File "/Users/zakuro/src/gitlab.com/akashipy/guji_delivery/venv/lib/python3.5/site-packages/sqlalchemy/orm/session.py", line 1612, in _save_or_update_state
    self._save_or_update_impl(state)
  File "/Users/zakuro/src/gitlab.com/akashipy/guji_delivery/venv/lib/python3.5/site-packages/sqlalchemy/orm/session.py", line 1867, in _save_or_update_impl
    self._save_impl(state)
  File "/Users/zakuro/src/gitlab.com/akashipy/guji_delivery/venv/lib/python3.5/site-packages/sqlalchemy/orm/session.py", line 1835, in _save_impl
    self._before_attach(state)
  File "/Users/zakuro/src/gitlab.com/akashipy/guji_delivery/venv/lib/python3.5/site-packages/sqlalchemy/orm/session.py", line 1956, in _before_attach
    state.session_id, self.hash_key))
sqlalchemy.exc.InvalidRequestError: Object '<ShopOwner at 0x110d3af98>' is already attached to session '1' (this is '7')

[xqliu]

I think you can just try to override the create_form or edit_form method from ModelView as below:

    def create_form(self, obj=None):
        form = super(ModelView, self).create_form(obj)
        # Do what you would like to do
        form.code.data = Product.get_next_code() #Set up value of a field
        form_util.filter_by_organization(form.category, ProductCategory) #Apply filter
        if not is_super_admin(): # Delete a field from UI.
            delattr(form, "organization")
        return form

You may also override scaffold_form method as below which will applies to both create an edit form.

    def scaffold_form(self):
        # Start with the standard form as provided by Flask-Admin. We've already told Flask-Admin to exclude the
        # password field from this form.
        form = super(UserAdmin, self).scaffold_form()

        # Add a password field, naming it "password2" and labeling it "New Password".
        form.password2 = PasswordField(label=lazy_gettext('New Password'),
                                             description=lazy_gettext('Left blank if you don\'t want to change it, '
                                                                      'input the new password to change it'))
        return form

Hope the above information helps you.

[panosangelopoulos]

Try the following example and keep us update if it works. If everything works fine then try to add validators and QuerySelectField.

from flask_admin.contrib.sqla import ModelView

class ShopOwnerForm(Form):
    name = StringField('Username')

class ShopOwnerAdmin(ModelView):
    form = ShopOwnerForm