QtAlchemy

QtAlchemy 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> 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

What is new in this release:

• Python 3 support! No 2to3 or other gotchas.
• SQLAlchemy 0.9x compatibility fixes

What is new in version 0.8.0:

• Change to PySide as default imports
• Relax license from GPL to LGPL
• Improve yoke change handling
• Create new PopupKeyListing for foreign key entry

What is new in version 0.7.1:

• QueryDataView gained basic ability to requery on column header clicks for sorting
• a few doc fixes
• new helper function family for using Geraldo in qtalchemy.ext.reporttools

What is new in version 0.7.0:

• improved exception error handling and reporting for GUI applications with-out console
• new yoke supporting a combo box
• improve yoke documentation
• add complete examples to front of documentation
• various model/list improvements including column width defaulting

What is new in version 0.6.12:

• BoundCommandMenu has slots to be dispatched from html binding entity commands to html viewing forms
• structured load and save extending the framework in BoundDialog
• new TreeView exposing the QTreeView
• tree model support in PBTableModel
• improved PySide portability and fixed various crash-bugs related to that

What is new in version 0.6.11:

• context sensitive help and status tips for fields
• new preCommand/refresh signals with CommandEvent structure allowing aborting by the ambient screen
• improvements in the generic data import wizard
• table view improvements (bug fixes, corrected model updates to be more precise)
• use pywin32 ShellExecute instead of os.system for better windows support

What is new in version 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)

Requirements:

• Python