Hi !
I'm using Python 3.6.5, Flask 1.0.2, SQLAlchemy 1.0.5 and I want to define
an attribute as a maximum between other two, based on flask-admin hybrid
property example
<https://github.com/flask-admin/flask-admin/blob/master/examples/sqla-hybrid_property/app.py>
:
from flask import Flaskfrom flask_sqlalchemy import SQLAlchemyfrom
sqlalchemy.ext.hybrid import hybrid_property
import flask_admin as adminfrom flask_admin.contrib import sqla
from sqlalchemy.sql.expression import func
# Create application
app = Flask(__name__)
# Create dummy secrey key so we can use sessions
app.config['SECRET_KEY'] = '123456790'
# Create in-memory database
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///sample_db_2.sqlite'
app.config['SQLALCHEMY_ECHO'] = True
db = SQLAlchemy(app)
# Flask views@app.route('/')def index():
return '<a href="/admin/">Click me to get to Admin!</a>'
class Screen(db.Model):
__tablename__ = 'screen'
id = db.Column(db.Integer, primary_key=True)
width = db.Column(db.Integer, nullable=False)
height = db.Column(db.Integer, nullable=False)
@hybrid_property
def max(self):
return max(self.height, self.width)
class ScreenAdmin(sqla.ModelView):
""" Flask-admin can not automatically find a hybrid_property yet. You will
need to manually define the column in list_view/filters/sorting/etc."""
column_list = ['id', 'width', 'height', 'max']
column_sortable_list = ['id', 'width', 'height', 'max']
# Flask-admin can automatically detect the relevant filters for hybrid
properties.
column_filters = ('max', )
# Create admin
admin = admin.Admin(app, name='Example: SQLAlchemy2',
template_mode='bootstrap3')
admin.add_view(ScreenAdmin(Screen, db.session))
if __name__ == '__main__':
# Create DB
db.create_all()
# Start app
app.run(debug=True)
But it fails, raising this error:
raise TypeError("Boolean value of this clause is not defined")
Traceback:
/home/bibo/usr/miniconda/envs/otroflask/lib/python3.6/site-packages/flask_sqlalchemy/__init__.py:794:
FSADeprecationWarning: SQLALCHEMY_TRACK_MODIFICATIONS adds significant
overhead and will be disabled by default in the future. Set it to True or
False to suppress this warning.
'SQLALCHEMY_TRACK_MODIFICATIONS adds significant overhead and 'Traceback
(most recent call last):
File "app.py", line 49, in <module>
admin.add_view(ScreenAdmin(Screen, db.session))
File
"/home/bibo/usr/miniconda/envs/otroflask/lib/python3.6/site-packages/flask_admin/contrib/sqla/view.py",
line 329, in __init__
menu_icon_value=menu_icon_value)
File
"/home/bibo/usr/miniconda/envs/otroflask/lib/python3.6/site-packages/flask_admin/model/base.py",
line 804, in __init__
self._refresh_cache()
File
"/home/bibo/usr/miniconda/envs/otroflask/lib/python3.6/site-packages/flask_admin/model/base.py",
line 881, in _refresh_cache
self._list_columns = self.get_list_columns()
File
"/home/bibo/usr/miniconda/envs/otroflask/lib/python3.6/site-packages/flask_admin/model/base.py",
line 1022, in get_list_columns
excluded_columns=self.column_exclude_list,
File
"/home/bibo/usr/miniconda/envs/otroflask/lib/python3.6/site-packages/flask_admin/contrib/sqla/view.py",
line 531, in get_column_names
column, path = tools.get_field_with_path(self.model, c)
File
"/home/bibo/usr/miniconda/envs/otroflask/lib/python3.6/site-packages/flask_admin/contrib/sqla/tools.py",
line 150, in get_field_with_path
value = getattr(current_model, attribute)
File
"/home/bibo/usr/miniconda/envs/otroflask/lib/python3.6/site-packages/sqlalchemy/ext/hybrid.py",
line 867, in __get__
return self._expr_comparator(owner)
File
"/home/bibo/usr/miniconda/envs/otroflask/lib/python3.6/site-packages/sqlalchemy/ext/hybrid.py",
line 1066, in expr_comparator
owner, self.__name__, self, comparator(owner),
File
"/home/bibo/usr/miniconda/envs/otroflask/lib/python3.6/site-packages/sqlalchemy/ext/hybrid.py",
line 1055, in _expr
return ExprComparator(cls, expr(cls), self)
File "app.py", line 34, in number_of_pixels
return max(self.width,self.height)
File
"/home/bibo/usr/miniconda/envs/otroflask/lib/python3.6/site-packages/sqlalchemy/sql/elements.py",
line 2975, in __bool__
raise TypeError("Boolean value of this clause is not defined")
I've tried with the max sqlalchemy function:
return func.max(self.height, self.width)
But it returns literally a function not a value.
I also tried to use concept of this answer
<https://stackoverflow.com/questions/42681231/sqlalchemy-boolean-value-of-this-clause-is-not-defined#42695255>,
without success.
Any idea?
Thanks!
--
SQLAlchemy -
The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
To post example code, please provide an MCVE: Minimal, Complete, and Verifiable
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