identity_key is returning an array with 3 arguments and breaking the code

https://github.com/flask-admin/flask-admin/blob/f04b71b78f75c2c5afdb50ceb2acf2ab27811d2b/flask_admin/contrib/sqla/fields.py#L299

I think it should not expect identity_key to return precisely two elements.

Traceback (most recent call last):
  File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 1997, in __call__
    return self.wsgi_app(environ, start_response)
  File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 1985, in wsgi_app
    response = self.handle_exception(e)
  File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 1540, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/usr/local/lib/python3.6/site-packages/flask/_compat.py", line 33, in reraise
    raise value
  File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 1982, in wsgi_app
    response = self.full_dispatch_request()
  File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 1614, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 1517, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/usr/local/lib/python3.6/site-packages/flask/_compat.py", line 33, in reraise
    raise value
  File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 1612, in full_dispatch_request
    rv = self.dispatch_request()
  File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 1598, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/usr/local/lib/python3.6/site-packages/flask_admin/base.py", line 69, in inner
    return self._run_view(f, *args, **kwargs)
  File "/usr/local/lib/python3.6/site-packages/flask_admin/base.py", line 368, in _run_view
    return fn(self, *args, **kwargs)
  File "/usr/local/lib/python3.6/site-packages/flask_admin/model/base.py", line 2076, in edit_view
    return_url=return_url)
  File "/usr/local/lib/python3.6/site-packages/flask_admin/base.py", line 308, in render
    return render_template(template, **kwargs)
  File "/usr/local/lib/python3.6/site-packages/flask/templating.py", line 134, in render_template
    context, ctx.app)
  File "/usr/local/lib/python3.6/site-packages/flask/templating.py", line 116, in _render
    rv = template.render(context)
  File "/usr/local/lib/python3.6/site-packages/jinja2/asyncsupport.py", line 76, in render
    return original_render(self, *args, **kwargs)
  File "/usr/local/lib/python3.6/site-packages/jinja2/environment.py", line 1008, in render
    return self.environment.handle_exception(exc_info, True)
  File "/usr/local/lib/python3.6/site-packages/jinja2/environment.py", line 780, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/usr/local/lib/python3.6/site-packages/jinja2/_compat.py", line 37, in reraise
    raise value.with_traceback(tb)
  File "/usr/local/lib/python3.6/site-packages/flask_admin/templates/bootstrap3/admin/model/edit.html", line 3, in top-level template code
    {% from 'admin/lib.html' import extra with context %} {# backward compatible #}
  File "/usr/local/lib/python3.6/site-packages/flask_admin/templates/bootstrap3/admin/master.html", line 1, in top-level template code
    {% extends admin_base_template %}
  File "/usr/local/lib/python3.6/site-packages/flask_admin/templates/bootstrap3/admin/base.html", line 37, in top-level template code
    {% block page_body %}
  File "/usr/local/lib/python3.6/site-packages/flask_admin/templates/bootstrap3/admin/base.html", line 77, in block "page_body"
    {% block body %}{% endblock %}
  File "/usr/local/lib/python3.6/site-packages/flask_admin/templates/bootstrap3/admin/model/edit.html", line 32, in block "body"
    {% block edit_form %}
  File "/usr/local/lib/python3.6/site-packages/flask_admin/templates/bootstrap3/admin/model/edit.html", line 33, in block "edit_form"
    {{ lib.render_form(form, return_url, extra(), form_opts) }}
  File "/usr/local/lib/python3.6/site-packages/jinja2/runtime.py", line 579, in _invoke
    rv = self._func(*arguments)
  File "/usr/local/lib/python3.6/site-packages/flask_admin/templates/bootstrap3/admin/lib.html", line 202, in template
    {% call form_tag(action=action) %}
  File "/usr/local/lib/python3.6/site-packages/jinja2/runtime.py", line 579, in _invoke
    rv = self._func(*arguments)
  File "/usr/local/lib/python3.6/site-packages/flask_admin/templates/bootstrap3/admin/lib.html", line 182, in template
    {{ caller() }}
  File "/usr/local/lib/python3.6/site-packages/jinja2/runtime.py", line 579, in _invoke
    rv = self._func(*arguments)
  File "/usr/local/lib/python3.6/site-packages/flask_admin/templates/bootstrap3/admin/lib.html", line 203, in template
    {{ render_form_fields(form, form_opts=form_opts) }}
  File "/usr/local/lib/python3.6/site-packages/jinja2/runtime.py", line 579, in _invoke
    rv = self._func(*arguments)
  File "/usr/local/lib/python3.6/site-packages/flask_admin/templates/bootstrap3/admin/lib.html", line 175, in template
    {{ render_field(form, f, kwargs) }}
  File "/usr/local/lib/python3.6/site-packages/jinja2/runtime.py", line 579, in _invoke
    rv = self._func(*arguments)
  File "/usr/local/lib/python3.6/site-packages/flask_admin/templates/bootstrap3/admin/lib.html", line 130, in template
    {{ field(**kwargs)|safe }}
  File "/usr/local/lib/python3.6/site-packages/wtforms/fields/core.py", line 153, in __call__
    return self.meta.render_field(self, kwargs)
  File "/usr/local/lib/python3.6/site-packages/wtforms/meta.py", line 56, in render_field
    return field.widget(field, **render_kw)
  File "/usr/local/lib/python3.6/site-packages/flask_admin/form/widgets.py", line 28, in __call__
    return super(Select2Widget, self).__call__(field, **kwargs)
  File "/usr/local/lib/python3.6/site-packages/wtforms/widgets/core.py", line 287, in __call__
    for val, label, selected in field.iter_choices():
  File "/usr/local/lib/python3.6/site-packages/flask_admin/contrib/sqla/fields.py", line 109, in iter_choices
    for pk, obj in self._get_object_list():
  File "/usr/local/lib/python3.6/site-packages/flask_admin/contrib/sqla/fields.py", line 102, in _get_object_list
    self._object_list = [(text_type(get_pk(obj)), obj) for obj in query]
  File "/usr/local/lib/python3.6/site-packages/flask_admin/contrib/sqla/fields.py", line 102, in <listcomp>
    self._object_list = [(text_type(get_pk(obj)), obj) for obj in query]
  File "/usr/local/lib/python3.6/site-packages/flask_admin/contrib/sqla/fields.py", line 299, in get_pk_from_identity
    cls, key = identity_key(instance=obj)
ValueError: too many values to unpack (expected 2)

[tarzanjw]

For ones who want to work with SQLAlchemy 1.2 and Flask-Admin, use sqlalchemy==1.2.0b3

[fruechel]

Don’t downgrade this package to 1.1.0, downgrade SQLAlchemy explicitly. Still use the most recent version of this package:

flask-admin
sqlalchemy<1.2

Something like that in requirements.txt.