Hi all,
when working with DataGrid in WPF application, I have found two bugs. I
am not sure they are IronPython bugs but I don't know how to investigate
more - I am not so fluent in WinDbg :-)
The first (more severe) bug is the /Object reference not set to an
instance of an object/ error. The attached sample consists of DataGrid
with some items and property /sel_item/ that is bound to
DataGrid.SelectedItem. When you try to disable the whole DataGrid (click
the button), the /Object reference not set to an instance of an object/
appears:
Traceback (most recent call last):
File "C:\IronPython-2.6.1\wpf.grid.py", line 109, in <module>
File "C:\IronPython-2.6.1\wpf.grid.py", line 103, in btnClick
SystemError: Object reference not set to an instance of an object.>>>
It only appears when you use binding to DataGrid.SelectedItem. If you
remove the binding (lines 21-22; in xaml), no error appears.
The second error appears when you initialize /sel_item/ to None (change
line 73 to: self.sel_item = None). The DataGrid has initially no
selected row. When you click on any, the binding error appears:
TypeConverter cannot convert from DataItem.
I guess this is more likely to be correct behavior because the Binding
is initialized with None instead of the row type so it has no way to
find out the right conversion.
I use IronPython 2.6.1 and WFP Toolkit from February 2010.
It would be nice if somebody could check these bugs. Thanks.
--
-- Lukáš
import clr
import clrtype
import pyevent
clr.AddReference('PresentationFramework')
clr.AddReference('PresentationCore')
clr.AddReference('WindowsBase')
clr.AddReference('WPFToolkit')
from System.Windows import Application
from System.ComponentModel import INotifyPropertyChanged,
PropertyChangedEventArgs
from System.Collections.ObjectModel import ObservableCollection
from System.Windows.Markup import XamlReader
from System.Windows.Controls import Validation
from System.Windows import RoutedEventHandler
xaml = """ <Window Width="200" Height="200"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation";
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml";
xmlns:data="http://schemas.microsoft.com/wpf/2008/toolkit";>
<StackPanel>
<data:DataGrid x:Name="grdItems" ItemsSource="{Binding data}"
SelectedItem="{Binding sel_item, Mode=TwoWay,
ValidatesOnExceptions=True, NotifyOnValidationError=True}"/>
<TextBlock Text="{Binding sel_item.value}" HorizontalAlignment="Center" />
<Button x:Name="btn" Width="150" Height="23" Content="Disable grid"/>
</StackPanel>
</Window>"""
class NotifyPropertyChangedBase(INotifyPropertyChanged):
PropertyChanged = None
def __init__(self):
self.PropertyChanged, self._propertyChangedCaller = pyevent.make_event()
def add_PropertyChanged(self, value):
self.PropertyChanged += value
def remove_PropertyChanged(self, value):
self.PropertyChanged -= value
def OnPropertyChanged(self, propertyName):
if self.PropertyChanged is not None:
self._propertyChangedCaller(self,
PropertyChangedEventArgs(propertyName))
class DataItem(NotifyPropertyChangedBase):
__metaclass__ = clrtype.ClrClass
def __init__(self, value):
super(DataItem, self).__init__()
self.value = value
@property
@clrtype.accepts()
@clrtype.returns(str)
def value(self):
return self._value
@value.setter
@clrtype.accepts(str)
@clrtype.returns()
def value(self, value):
self._value = value
self.OnPropertyChanged('value')
class ModelClass(NotifyPropertyChangedBase):
__metaclass__ = clrtype.ClrClass
def __init__(self):
super(ModelClass, self).__init__()
self._data = ObservableCollection[DataItem]()
self.data.Add(DataItem('one'))
self.data.Add(DataItem('two'))
self.data.Add(DataItem('three'))
self.sel_item = self.data[1]
@property
@clrtype.accepts()
@clrtype.returns(DataItem)
def sel_item(self):
return self._sel_item
@sel_item.setter
@clrtype.accepts(DataItem)
@clrtype.returns()
def sel_item(self, value):
self._sel_item = value
self.OnPropertyChanged('sel_item')
@property
@clrtype.accepts()
@clrtype.returns(ObservableCollection[DataItem])
def data(self):
return self._data
class MyApp:
def __init__(self):
self.root = XamlReader.Parse(xaml)
self.root.DataContext = ModelClass()
self.root.AddHandler(Validation.ErrorEvent,
RoutedEventHandler(self.OnBindingValidationError))
self.root.FindName('btn').Click += self.btnClick
def btnClick(self, sender, event):
self.root.FindName('grdItems').IsEnabled = False
def OnBindingValidationError(self, sender, event):
print event.Error.ErrorContent
app = Application()
app.Run(MyApp().root)
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