public SelectionDescriptorBuilder()
{
_builder = VMDescriptorBuilder
.OfType <TDescriptor>()
.For <TVM>()
.WithProperties((d, b) => { });
}
public IVMPropertyDescriptor <MultiSelectionVM <TItemSource> > WithCaption(
Func <TItemSource, string> captionGetter,
Action <MultiSelectionWithCaptionDescriptorBuilder <TSourceObject, TItemSource> > descriptorConfigurationAction = null
)
{
Check.NotNull(captionGetter, nameof(captionGetter));
Check.Requires <InvalidOperationException>(_selectedSourceItemsPropertyFactory != null);
SelectionItemVMDescriptor itemDescriptor = VMDescriptorBuilder
.OfType <SelectionItemVMDescriptor>()
.For <SelectionItemVM <TItemSource> >()
.WithProperties((d, c) => {
var s = c.GetPropertyBuilder(x => x.Source);
d.Caption = s.Property.DelegatesTo(captionGetter);
})
.WithValidators(b => b.EnableParentViewModelValidation())
.Build();
var allSourceItemsPropertyFactory =
_allSourceItemsPropertyFactory ??
CreateLocatingPropertyFactory();
var descriptorBuilder = new MultiSelectionWithCaptionDescriptorBuilder <TSourceObject, TItemSource>(
_filter,
itemDescriptor
);
descriptorBuilder.WithProperties((d, b) => {
var s = b.GetPropertyBuilder(x => x.Source);
d.AllSourceItems = allSourceItemsPropertyFactory(s);
d.SelectedSourceItems = _selectedSourceItemsPropertyFactory(s);
});
if (_undoIsEnabled)
{
descriptorBuilder.WithViewModelBehaviors(b => {
b.EnableUndo();
});
}
if (descriptorConfigurationAction != null)
{
descriptorConfigurationAction(descriptorBuilder);
}
var descriptor = descriptorBuilder.Build();
var property = _sourceObjectPropertyBuilder.Custom.ViewModelProperty <MultiSelectionVM <TItemSource> >(
valueAccessor: new MultSelectionAccessor(descriptor),
sourceAccessor: _sourceObjectPropertyBuilder.Custom.CreateSourceObjectAccessor()
);
return(property);
}
private static SelectableItemVMDescriptor <TItemVM> CreateItemDescriptor(bool isSelectedRaisesPropertyChanged)
{
return(VMDescriptorBuilder
.OfType <SelectableItemVMDescriptor <TItemVM> >()
.For <SelectableItemVM <TItemSource, TItemVM> >()
.WithProperties((d, c) => {
var v = c.GetPropertyBuilder();
d.IsSelected = v.Property.Of <bool>();
d.VM = v.VM.Wraps(x => x.Source).With <TItemVM>();
})
.WithValidators(b => b.EnableParentViewModelValidation())
.WithBehaviors(b => {
if (!isSelectedRaisesPropertyChanged)
{
// HACK: This behavior needs to be disabled to workaround the following problem:
//
// * A 'MultiSelection' with 'SelectableItemVM' elements (configured with 'Of<TItemVM>' instead
// of 'WithCaption') is bound to a ComboBox (specifically a DevExpress WPF ComboBoxEdit).
// * The user changes the selected items in the control.
// * The ComboBox sets the selected items via 'SettableListDisplayValueBehavior'.
// * Each collection modification in 'SettableListDisplayValueBehavior.SynchronizeCollections' causes
// the 'IsSelected' property of added or removed 'SelectableItemVM' objects to change (because of
// the dependency defined in the constructor of 'MultiSelectionDescriptorBuilder').
// * This change raises a 'PropertyChanged' event for the 'IsSelected' property.
// * This 'PropertyChanged' event triggers a call of 'VMCollection.OnListChanged' with 'ListChangedType.ItemChanged'.
// * The 'ListChanged' event that is raised in the base 'OnListChanged' method is handled by the ComboBox.
// * The ComboBox reacts to the 'ListChanged' event by setting the value of the MultiSelection again.
// * This calls the 'SettableListDisplayValueBehavior' again. Now there are two calls of its
// 'SynchronizeCollections' method in the call stack, one from the initial call caused by the user
// interaction and one that was triggered by the 'ListChanged' event.
// * That second call to 'SynchronizeCollections' might again cause 'PropertyChanged' and 'ListChanged' events.
// * After the code returns to the first call of 'SynchronizeCollections' and tries to modify the
// next element in the collection, the code in 'SynchronizerCollectionBehavior' notices that the
// collections are not in sync any more since the second call to 'SettableListDisplayValueBehavior.SynchronizeCollections'
// modified the same collection that the first one was still modifying. This causes the
// 'SynchronizerCollectionBehavior' to throw an InvalidOperationException
// (error message "The VM collection is not in sync with its source collection anymore.").
//
// To prevent this, the behavior that causes the 'PropertyChanged' event of the 'IsSelected' property
// to be raised is disabled here.
// But this is only ok if the 'MultiSelection' is used in a ComboBox. If it's used in a 'ListBox'
// where the control directly modifies the 'IsSelected' properties (instead of setting the whole
// 'SelectedItems' collection) the 'PropertyChanged' event is required to synchronize the changes
// to the collections.
b.Property(x => x.IsSelected).Disable(PropertyBehaviorKeys.ChangeNotifier);
}
})
.Build());
}
private static SelectableItemVMDescriptor <TItemVM> CreateItemDescriptor()
{
return(VMDescriptorBuilder
.OfType <SelectableItemVMDescriptor <TItemVM> >()
.For <SelectableItemVM <TItemSource, TItemVM> >()
.WithProperties((d, c) => {
var v = c.GetPropertyBuilder();
d.IsSelected = v.Property.Of <bool>();
d.VM = v.VM.Wraps(x => x.Source).With <TItemVM>();
})
.WithValidators(b => b.EnableParentViewModelValidation())
.Build());
}
