添加相关记录时 Flask-Admin 崩溃

Question

我已经将这个问题从我的数据库的大规模部署归结为我能做的最精简的版本，但我仍然收到这个错误。

下面是使用 Flask_SQLAlchemy 的非常简单的数据库结构的代码。

from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_admin import Admin
from flask_admin.contrib.sqla import ModelView
import os

app = Flask(__name__)
basedir = os.path.abspath(os.path.dirname(__file__))

app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:////' + os.path.join(basedir, 'app.db')
app.config['SECRET_KEY'] = 'mysec'

db = SQLAlchemy(app)

class Client(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    clientname = db.Column(db.String(50))
    sessions = db.relationship('Session', backref='client', lazy='dynamic')

    def __repr__(self):
        return '<Client %r>' % (self.clientname)

class Session(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    sessionname = db.Column(db.String(50))
    accept = db.Column(db.String(50))
    client_id = db.Column(db.Integer, db.ForeignKey('client.id'))

    def __repr__(self):
        return '<Session %r>' % (self.sessionname)

admin = Admin(app)
admin.add_view(ModelView(Client, db.session))
admin.add_view(ModelView(Session, db.session))

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

这工作正常，数据库构建正常。关系似乎没问题，但是当我去 Flask-Admin 向 Client 或 Session 添加记录时（且仅当）另一个 table 中有记录时，我收到以下错误：

[2018-01-16 16:30:17,394] ERROR in app: Exception on /admin/session/new/ [GET]
Traceback (most recent call last):
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/flask/app.py", line 1982, in wsgi_app
    response = self.full_dispatch_request()
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/flask/app.py", line 1614, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/flask/app.py", line 1517, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/flask/app.py", line 1612, in full_dispatch_request
    rv = self.dispatch_request()
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/flask/app.py", line 1598, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/flask_admin/base.py", line 69, in inner
    return self._run_view(f, *args, **kwargs)
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/flask_admin/base.py", line 368, in _run_view
    return fn(self, *args, **kwargs)
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/flask_admin/model/base.py", line 2024, in create_view
    return_url=return_url)
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/flask_admin/base.py", line 308, in render
    return render_template(template, **kwargs)
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/flask/templating.py", line 134, in render_template
    context, ctx.app)
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/flask/templating.py", line 116, in _render
    rv = template.render(context)
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/jinja2/environment.py", line 1008, in render
    return self.environment.handle_exception(exc_info, True)
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/jinja2/environment.py", line 780, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/flask_admin/templates/bootstrap2/admin/model/create.html", line 3, in top-level template code
    {% from 'admin/lib.html' import extra with context %} {# backward compatible #}
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/flask_admin/templates/bootstrap2/admin/master.html", line 1, in top-level template code
    {% extends admin_base_template %}
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/flask_admin/templates/bootstrap2/admin/base.html", line 35, in top-level template code
    {% block page_body %}
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/flask_admin/templates/bootstrap2/admin/base.html", line 64, in block "page_body"
    {% block body %}{% endblock %}
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/flask_admin/templates/bootstrap2/admin/model/create.html", line 22, in block "body"
    {% block create_form %}
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/flask_admin/templates/bootstrap2/admin/model/create.html", line 23, in block "create_form"
    {{ lib.render_form(form, return_url, extra(), form_opts) }}
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/jinja2/runtime.py", line 579, in _invoke
    rv = self._func(*arguments)
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/flask_admin/templates/bootstrap2/admin/lib.html", line 212, in template
    {% call form_tag(action=action) %}
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/jinja2/runtime.py", line 579, in _invoke
    rv = self._func(*arguments)
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/flask_admin/templates/bootstrap2/admin/lib.html", line 191, in template
    {{ caller() }}
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/jinja2/runtime.py", line 579, in _invoke
    rv = self._func(*arguments)
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/flask_admin/templates/bootstrap2/admin/lib.html", line 213, in template
    {{ render_form_fields(form, form_opts=form_opts) }}
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/jinja2/runtime.py", line 579, in _invoke
    rv = self._func(*arguments)
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/flask_admin/templates/bootstrap2/admin/lib.html", line 183, in template
    {{ render_field(form, f, kwargs) }}
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/jinja2/runtime.py", line 579, in _invoke
    rv = self._func(*arguments)
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/flask_admin/templates/bootstrap2/admin/lib.html", line 137, in template
    {{ field(**kwargs)|safe }}
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/wtforms/fields/core.py", line 153, in __call__
    return self.meta.render_field(self, kwargs)
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/wtforms/meta.py", line 56, in render_field
    return field.widget(field, **render_kw)
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/flask_admin/form/widgets.py", line 28, in __call__
    return super(Select2Widget, self).__call__(field, **kwargs)
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/wtforms/widgets/core.py", line 287, in __call__
    for val, label, selected in field.iter_choices():
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/site-packages/flask_admin/contrib/sqla/fields.py", line 109, in iter_choices
    for pk, obj in self._get_object_list():
  File "/home/maingame/come_flask_obt/env/local/lib/python2.7/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 "/home/maingame/come_flask_obt/env/local/lib/python2.7/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

Answer 1

感谢@Doobeh，只需将“sqlalchemy==1.2.0b3”添加到我的 requirements.txt 并安装它，我的问题就解决了。较新版本的 SQLAlchemy 似乎不适用于 Flask-Admin 的某些关系类型。

https://github.com/flask-admin/flask-admin/issues/1583

Answer 2

问题现在应该已经解决了。根据 https://github.com/flask-admin/flask-admin/issues/1583 Flask-Admin 的说法，如果您直接从 master 分支中拉取它，那么 Flask-Admin 应该可以与更新版本的 sqlalchemy 一起工作。

添加相关记录时 Flask-Admin 崩溃

Flask-Admin crashing when adding related record

python

flask

flask-sqlalchemy

flask-wtforms

flask-admin