qtalchemy 0.6.10

QtAlchemy is a framework for developing GUI database applications using SQLAlchemy and PyQt.

Introduction

The QtAlchemy library is a collection of Qt Model-View classes and helper functions to aid in rapid development of desktop database applications. It aims to provide a strong API for exposing foreign key relationships in elegant and immediate ways to the user of applications. Context menus, searches and combo-boxes and tabbed interfaces are all utilized. The use of SQLAlchemy makes it possible that these features are supported on a variety of database backends with virtually no code changes.

The Command class gives a way to construct menus and toolbars from decorated python functions. The power of this becomes more evident when bound to a view where the command function can then receive the identifier of the selected item of the view. This provides a flexible way to link commands to any sqlalchemy query generated views.

Full documentation is available at http://qtalchemy.org .

QtAlchemy has been developed with python 2.6.x, SQLAlchemy 0.6.x and PyQt 4.7.x. It is expected that it would be functional on all nearby versions. There is an effort made to make sure that feature parity is attained for windows and linux (and mac too, but I don’t have one).

QtAlchemy is expected to fully work with PySide as of version 1.0.4. PySide support can be enabled by running the use_pyside.sh shell script which merely changes the imports from PyQt4 to PySide.

Example

In the interests of being concise, the example given here does not reference a database.

QtAlchemy using API2 of PyQt so we need to enable that before importing PyQt4

>>> import sip
>>> sip.setapi('QString', 2)
>>> sip.setapi('QVariant', 2)

The UserAttr property class provides yet another type defined python property. The purpose of reinventing this was to ensure that we could interact with our models sufficiently and provide a uniform experience for SQLAlchemy column properties and UserAttr properties.

>>> from qtalchemy import UserAttr
>>> import datetime
>>> class Person(object):
...     name=UserAttr(str,"Name")
...     birth_date=UserAttr(datetime.date,"Birth Date")
...     age=UserAttr(int,"Age (days)",readonly=True)
...
...     @age.on_get
...     def age_getter(self):
...         return (datetime.date.today()-self.birth_date).days

With this declaration, we can declare a person and compute their age:

>>> me = Person()
>>> me.name = "Joel"
>>> me.birth_date = datetime.date(1979,1,9)
>>> me.age  #depends on today! -- #doctest: +SKIP
11746
>>> me.age-(datetime.date.today()-datetime.date(2011,1,9)).days  # on birthday 1<<5
11688

We can create a dialog showing the name & birth-date. The main magic happens in the addBoundForm call which obtains labels from the UserAttr classes and places the correct edit widgets on screen.

>>> from PyQt4 import QtCore, QtGui
>>> from qtalchemy import MapperMixin, LayoutLayout, ButtonBoxButton, LayoutWidget
>>>
>>> class PersonEdit(QtGui.QDialog,MapperMixin):
...     def __init__(self,parent,person):
...         QtGui.QDialog.__init__(self,parent)
...         MapperMixin.__init__(self)
...
...         self.person = person
...
...         vbox = QtGui.QVBoxLayout(self)
...         mm = self.mapClass(Person)
...         mm.addBoundForm(vbox,["name","birth_date"])
...         mm.connect_instance(self.person)
...
...         buttons = LayoutWidget(vbox,QtGui.QDialogButtonBox())
...         self.close_button = ButtonBoxButton(buttons,QtGui.QDialogButtonBox.Ok)
...         buttons.accepted.connect(self.btnClose)
...
...     def btnClose(self):
...         self.submit() # changes descend to model on focus-change; ensure receiving the current focus
...         self.close()

And, now, we only need some app code to actually kick this off

>>> app = QtGui.QApplication([])
>>> sam = Person()
>>> sam.name = "Samuel"
>>> d = PersonEdit(None,sam)
>>> d.exec_()  # gui interaction -- #doctest: +SKIP
0
>>> sam.age    # assumes selection of yesterday in the gui -- #doctest: +SKIP
1

Development

QtAlchemy is still in heavy core development as much as my work schedule allows. The documentation is growing as the ideas are fleshed out and I learn sphinx for the general documentation generation. We strive for full doc-test coverage as possible, but PyQt model-view and gui impose certain complications on doc-tests.

My expectations for 0.7 continue to increase so I gave in to a 0.6.10 release under the new name of qtalchemy. This comes paired with a brand new (and not really finished) web page http://qtalchemy.org. Before a 0.7 release, I aim to have:

• document InputYoke selection

• PBMdiTable and PBSearchDialog move to qtalchemy.ext

Changelog

0.6.10:

• renamed to qtalchemy

• exposed Qt’s association of icons with commands appearing in menus and toolbars

• moved qtalchemy.PBTable to qtalchemy.widgets.TableView

• new qtalchemy.ext module for common dialogs (a data import wizard for now)

0.6.9:

• wrote a broad outline of documentation

• added boolean, time, and formatted text input yokes

• rewrote DialogGeo as WindowGeometry saving and restoring window and splitter geometry for arbitrary windows

• brand new command structure replacing DomainEntity

0.6.8:

• color and font control in the python business object layer

• improved packaging support for windows

• QGridLayout support in WidgetAttributeMapper

• extended UserAttr value storage to include attribute paths (e.g. self.sub.sub1.value)

• new QtAlchemy.xplatform module for cross platform helpers

• rewrote WidgetAttributeMapper using InputYoke methodology

• rename PBEventMappedBase to ModelObject

• additions and corrections to examples

• event model corrections (more needed)

0.6:

• new QtAlchemy.widgets sub-module for QLineEdit derived classes (others in the future)

• new QtAlchemy.dialogs sub-module for auth dialog classes

• continued tweaks for PySide and nosetests

0.5.1

• first usable (??) release

License

QtAlchemy is licensed under the GPL for the moment due to the heavy dependency on PyQt making it pointless (and essentially impossible) to be LGPL. It is expected that QtAlchemy would move to PySide and become LGPL when PySide is acceptably stable.