Merge pull request #962 from pawl/fix-hybrid-properties

Fix SQLAlchemy hybrid_property support, add example and test

examples/sqla-hybrid_property/README.rst

+Example of how to use (and filter on) a hybrid_property with the SQLAlchemy backend.
+
+Hybrid properties allow you to treat calculations (for example: first_name + last_name)
+like any other database column.
+
+To run this example:
+
+1. Clone the repository::
+
+    git clone https://github.com/flask-admin/flask-admin.git
+    cd flask-admin
+
+2. Create and activate a virtual environment::
+
+    virtualenv env
+    source env/bin/activate
+
+3. Install requirements::
+
+    pip install -r 'examples/sqla-hybrid_property/requirements.txt'
+
+4. Run the application::
+
+    python examples/sqla-hybrid_property/app.py
+
+The first time you run this example, a sample sqlite database gets populated automatically. To suppress this behaviour,
+comment the following lines in app.py:::
+
+    if not os.path.exists(database_path):
+        build_sample_db()

examples/sqla-hybrid_property/__init__.py

+

examples/sqla-hybrid_property/app.py

+from flask import Flask
+from flask_sqlalchemy import SQLAlchemy
+from sqlalchemy.ext.hybrid import hybrid_property
+
+import flask_admin as admin
+from flask_admin.contrib import sqla
+from flask_admin.contrib.sqla.filters import IntGreaterFilter
+
+# 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 number_of_pixels(self):
+        return self.width * self.height
+
+
+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.'''
+    list_columns = ['id', 'width', 'height', 'number_of_pixels']
+    column_sortable_list = ['id', 'width', 'height', 'number_of_pixels']
+
+    # make sure the type of your filter matches your hybrid_property
+    column_filters = [IntGreaterFilter(Screen.number_of_pixels,
+                                       'Number of Pixels')]
+
+
+# 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)

examples/sqla-hybrid_property/requirements.txt

+Flask
+Flask-Admin
+Flask-SQLAlchemy

flask_admin/contrib/sqla/view.py

@@ -4,7 +4,7 @@ import inspect
 
 from sqlalchemy.orm.attributes import InstrumentedAttribute
 from sqlalchemy.orm import joinedload, aliased
-from sqlalchemy.sql.expression import desc
+from sqlalchemy.sql.expression import desc, ColumnElement
 from sqlalchemy import Boolean, Table, func, or_
 from sqlalchemy.exc import IntegrityError
 
@@ -550,8 +550,11 @@ class ModelView(BaseModelView):
         if attr is None:
             raise Exception('Failed to find field for filter: %s' % name)
 
-        # Figure out filters for related column
-        if hasattr(attr, 'property') and hasattr(attr.property, 'direction'):
+        # Figure out filters for related column, unless it's a hybrid_property
+        if isinstance(attr, ColumnElement):
+            warnings.warn(('Unable to scaffold the filter for %s, scaffolding '
+                           'for hybrid_property is not supported yet.') % name)
+        elif hasattr(attr, 'property') and hasattr(attr.property, 'direction'):
             filters = []
 
             for p in self._get_model_iterator(attr.property.mapper.class_):
@@ -620,7 +623,9 @@ class ModelView(BaseModelView):
         if isinstance(filter, sqla_filters.BaseSQLAFilter):
             column = filter.column
 
-            if self._need_join(column.table):
+            # hybrid_property joins are not supported yet
+            if (isinstance(column, InstrumentedAttribute) and
+                    self._need_join(column.table)):
                 self._filter_joins[column] = [column.table]
 
         return filter

flask_admin/tests/sqla/test_basic.py

@@ -8,6 +8,8 @@ from flask_admin._compat import iteritems
 from flask_admin.contrib.sqla import ModelView, filters
 from flask_babelex import Babel
 
+from sqlalchemy.ext.hybrid import hybrid_property
+
 from . import setup
 
 from datetime import datetime, time, date
@@ -1217,6 +1219,53 @@ def test_column_filters():
     ok_('test1_val_2' not in data)
 
 
+def test_hybrid_property():
+    app, db, admin = setup()
+
+    class Model1(db.Model):
+        id = db.Column(db.Integer, primary_key=True)
+        name = db.Column(db.String)
+        width = db.Column(db.Integer)
+        height = db.Column(db.Integer)
+
+        @hybrid_property
+        def number_of_pixels(self):
+            return self.width * self.height
+
+    db.create_all()
+
+    db.session.add(Model1(id=1, name="test_row_1", width=25, height=25))
+    db.session.add(Model1(id=2, name="test_row_2", width=10, height=10))
+    db.session.commit()
+
+    client = app.test_client()
+
+    view = CustomModelView(
+        Model1, db.session,
+        column_default_sort='number_of_pixels',
+        column_filters = [filters.IntGreaterFilter(Model1.number_of_pixels,
+                                                   'Number of Pixels')]
+    )
+    admin.add_view(view)
+
+    # filters - hybrid_property integer - greater
+    rv = client.get('/admin/model1/?flt0_0=600')
+    eq_(rv.status_code, 200)
+    data = rv.data.decode('utf-8')
+    ok_('test_row_1' in data)
+    ok_('test_row_2' not in data)
+
+    # sorting
+    rv = client.get('/admin/model1/?sort=0')
+    eq_(rv.status_code, 200)
+
+    _, data = view.get_list(0, None, None, None, None)
+
+    eq_(len(data), 2)
+    eq_(data[0].name, 'test_row_2')
+    eq_(data[1].name, 'test_row_1')
+
+
 def test_url_args():
     app, db, admin = setup()