hybrid_properties

[marplatense]

I was under the impression issue 11 would include hybrid_properties but I cannot make them work. Consider the following example where gender is a synonym for _gender:

  from formalchemy import Column
  from formalchemy.forms import FieldSet
  from sqlalchemy import Table, Unicode, Integer, create_engine, MetaData
  from sqlalchemy.ext.declarative import declarative_base
  from sqlalchemy.ext.hybrid import hybrid_property
  from sqlalchemy.orm import sessionmaker
  session = sessionmaker()
  Session = session()
  engine = create_engine('postgresql://usr:pass@localhost/db', echo=True)
  Session.configure(bind=engine)
  m = MetaData()
  m.bind = engine
  base = declarative_base(metadata=m)

  class Test(base):
      __tablename__ = "example"
      id = Column(Integer, autoincrement=True, primary_key=True)
      name = Column(Unicode(100), nullable=False)
      _gender = Column(Unicode(1), nullable=False, default=True)
     @hybrid_property
     def gender(self):
          return self._gender
     @gender.setter
     def gender(self, value):
          if value.upper() not in ('F', 'M'):
              raise(Exception(u'Gender must be F or M'))
          else:
              self._gender = value.upper()

  m.create_all()

  fs1 = FieldSet(Test())
  fs1.configure(include=[fs1.name, fs1.gender])
  fs1.render()

When I execute it, I'm getting:

  Traceback (most recent call last):
    File "<ipython-input-3-37113d7b6e1e>", line 1, in <module>
      import property_fa as f
    File "property_fa.py", line 35, in <module>
      fs1.configure(include=[fs1.name, fs1.gender])
    File "/home/mariano/Code/example/env/lib/python2.7/site-packages/FormAlchemy-1.4.1-py2.7.egg/formalchemy/forms.py", line 773, in __getattr__
      raise AttributeError(attrname)
  AttributeError: gender

If I use _gender as the included field, of course it works however it bypasses my property control.

TIA, Mariano

[smurfix]

formalchemy works by analyzing sqlalchemy's internal data structures. The problem is that hybrid_property is just a utility function which implements a fancy way of generating a property class; it doesn't hook into sqlalchemy at all, so formalchemy doesn't see it.

Therefore, you need to create the 'gender' attribute yourself. This is simple enough:

from formalchemy.fields import AttributeField
t = Test()
fs1 = FieldSet(t)
gf = AttributeField(Test.gender,fs1)
gf.name="gender"
fs1.append(gf)
fs1.configure(include=[fs1.name, fs1.gender])
fs1.render()

[mikepk]

I just hit this same problem, what's odd is that older versions of FormAlchmey did seem to work with synonyms and hybrid_property but newer versions don't. I'm not sure exactly where the break happened but FormAlchemy==1.4.3 does allow them. In the following example 'password' is a synonym for _password. The only difference between the two was moving from my pinned FA version to the latest.

1.4.3

>>> from formalchemy import FieldSet
>>> fs = FieldSet(User)
>>> print fs.password
AttributeField(password)

1.5.5

>>> from formalchemy import FieldSet
>>> fs = FieldSet(User)
>>> print fs.password
Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/usr/share/ps/venv/qs2/local/lib/python2.7/site-packages/formalchemy/forms.py", line 799, in __getattr__
    raise AttributeError(attrname)
AttributeError: password

[mikepk]

Created a pull request #64 with changes restoring the older synonym / hybrid_property exposing behavior.