def test_example1():
'''
The simplest case that shows how a view model can be
automatically connected with a view (window).
'''
class Model(object):
def __init__(self):
self._text = 'initial text'
self._switch = True
text = pr.property_a('_text')
switch = pr.property_a('_switch')
def action(self):
print 'Action fired', self.text, self.switch
# Create a model and a Qt window.
# Link them automatically via object names and property names
model = Model()
view = example_view()
pyside.hookup_all(model, view)
# The initial model value is propagated to the view
assert view.text.text() == 'initial text'
# Changes in the view go back to the model
view.text.setText('changed')
view.text.editingFinished.emit()
assert model._text == 'changed'
def test_converters():
'''
We'll show two things in this example:
- how the property data can be sourced externally,
- how to do some conversions
'''
class Model(object):
value = 10
class ViewModel(object):
text = pr.property_a('value', '_model', show=str, read=int)
model = Model()
viewmodel = ViewModel()
viewmodel._model = model
view = example_view()
pyside.hookup_all(viewmodel, view)
# Now the property is accessible as `text` in the viewmodel,
# but the value is sourced from `._model.value`
# and also converted using given functions (`str` and `read` respectively).
assert model.value == 10
assert viewmodel.text == view.text.text() == '10'
view.text.setText(' 20 ')
view.text.editingFinished.emit()
assert model.value == 20
assert viewmodel.text == '20'
assert view.text.text() == ' 20 '
# Note: The value in the view still has the spaces, just as typed.
# But the viewmodel doesn't know of these spaces -
# - when asked about the value, converts and gives the current model's value.
# Interestingly, if the viewmodel's property had change notification,
# the view-triggered change would ring a callback back to the view,
# and the view would update with the converted '20' without spaces.
# Let us verify that:
ViewModel.text = pr.property_a('value','_model', cn=True, show=str, read=int)
view = example_view()
pyside.hookup_all(viewmodel, view)
view.text.setText(' 30 ')
view.text.editingFinished.emit()
assert model.value == 30
assert viewmodel.text == view.text.text() == '30'
def test_enabled():
'''
Metadata example. Plug a method to indicate when a property is "enabled".
'''
class Model(object):
switch = pr.property_a('_switch', cn=True)
text = pr.property_a('_text', cn=True)
_switch = True
_text = 'text'
@text('enabled')
def textbox_enabled(self):
return self.switch
model = Model()
# The above setup allows to check if 'text' is enabled at a given moment
model.switch = False
assert not Model.text.is_enabled(model)
model.switch = True
assert Model.text.is_enabled(model)
# However, the view will need to be notified that
# something about property 'text' changes whenever the property 'switch' changes.
# But that's why we have change notification:
def callback():
Model.text.notify(model)
Model.switch.subscribe(model, callback)
# We're basically telling the property `switch` to call the callback whenever it changes,
# in order to instruct the property `text` to tell all interested views that it changed too.
# Let's see it in action:
view = example_view()
pyside.hookup_all(model, view)
assert model.switch == True
assert view.text.isEnabled()
view.switch.setChecked(False)
assert not view.text.isEnabled()
# demo : variants
def test_example2():
'''
This case shows how properties with change notification
allow for 2-way data binding.
'''
class Model(object):
def __init__(self):
self._text = 'text'
self._switch = True
self._count = 0
text = pr.property_a('_text', cn=True)
switch = pr.property_a('_switch', cn=True)
def action(self):
self.text += ' ... and more'
model = Model()
view = example_view()
pyside.hookup_all(model, view)
# Likewise, the view is initialised to the initial values from the model
# However, further model edits now get propagated too
assert view.text.text() == 'text'
view.action.click()
assert view.text.text() == model._text == 'text ... and more'
# Change notification is automatically triggered when setting the property,
# but not when directly editing the backing field, of course:
model._text = 'something else'
assert view.text.text() == 'text ... and more'
# But you can fire the change notification manually anytime
Model.text.notify(model)
assert view.text.text() == 'something else'