我正在为一个新项目尝试使用caliburn.micro框架,但我坚持使用绑定ListPicker(工具包中的那个)。当我将控件更改为简单的DropDown时,一切都按预期工作。 我假设DropDown工作正常,因为实现了here的默认约定:
AddElementConvention<Selector>(Selector.ItemsSourceProperty, "SelectedItem", "SelectionChanged")
.ApplyBinding = (viewModelType, path, property, element, convention) => {
if (!SetBinding(viewModelType, path, property, element, convention))
return false;
ConfigureSelectedItem(element, Selector.SelectedItemProperty,viewModelType, path);
ApplyItemTemplate((ItemsControl)element, property);
return true;
};
ListPicker没有实现Selector,所以我试图在我的引导程序中添加自定义约定:
static void AddCustomConventions() {
AddElementConvention<ListPicker>(ListPicker.ItemsSourceProperty, "SelectedItem", "SelectionChanged")
.ApplyBinding = (viewModelType, path, property, element, convention) => {
ConventionManager.ConfigureSelectedItem(element, ListPicker.SelectedItemProperty,viewModelType, path);
return true;
};
}
不幸的是,那不起作用。你能帮忙吗?
答案 0 :(得分:8)
我用这个惯例解决了我的问题。
ConventionManager.AddElementConvention<ListPicker>(ListPicker.ItemsSourceProperty, "SelectedItem", "SelectionChanged")
.ApplyBinding = (viewModelType, path, property, element, convention) =>
{
if (ConventionManager.GetElementConvention(typeof(ItemsControl)).ApplyBinding(viewModelType, path, property, element, convention))
{
ConventionManager.ConfigureSelectedItem(element, ListPicker.SelectedItemProperty, viewModelType, path);
return true;
}
return false;
};
另外,还有另一个问题。我的SelectedItem属性返回null但我的Items属性不包含空值。我得到一个例外,所选项目无效,因为它不在列表中。