WPF使用现有ItemsSource将对象添加到ListBox [英] WPF Adding an object to ListBox with existing ItemsSource

问题描述

嘿，我有一个列表框，我将ItemsSource设置为数据库中对象的ObservableCollection，并且需要在此列表的末尾添加一个对象.但是我一直收到无效的操作异常.不知何故，我的列表框正在使用中(在我看来，这是一个给定的，因为它已经显示，并且里面已经有项目.)这是我的列表框代码:

Hey I have a list box that I set the ItemsSource to be an ObservableCollection of objects from my database, and I need to add a single object at the end of this list. However I keep getting an invalid operation exception. Somehow my listbox is in use (which in my mind is a given as it is displayed and already have items inside.) Here is my code for the list box:

<ListBox x:Name="CarList" SelectionChanged="ItemSelected" ScrollViewer.HorizontalScrollBarVisibility="Disabled" Background="{x:Null}">
        <ListBox.ItemsPanel>
            <ItemsPanelTemplate>
                <WrapPanel FlowDirection="LeftToRight" ItemHeight="300" ItemWidth="300"/>
            </ItemsPanelTemplate>
        </ListBox.ItemsPanel>

        <ListBox.ItemTemplate>
            <DataTemplate>
                <Grid Margin="10,10">
                    <Grid.RowDefinitions>
                        <RowDefinition Height="*" />
                        <RowDefinition Height="35" />
                    </Grid.RowDefinitions>
                    <Image Grid.Row="0" Source="{Binding image_path}" VerticalAlignment="Stretch"/>
                    <Grid Grid.Row="1" Background="SteelBlue">
                        <TextBlock HorizontalAlignment="Left" VerticalAlignment="Center" Margin="3" Text="{Binding model}"/>
                        <TextBlock HorizontalAlignment="Right" VerticalAlignment="Center" Margin="3" Text="{Binding price}"/>
                    </Grid>
                </Grid>
            </DataTemplate>
        </ListBox.ItemTemplate>
</ListBox>

我首先像这样设置ItemsSource:

And I first set the ItemsSource like so:

CarList.ItemsSource = CarController.GetAllCars();

然后要添加我的自定义对象，如下所示:

And then want to add my custom object like this:

ListBoxItem carAdd = new ListBoxItem();
carAdd.Content = new CarModel{ image_path = "/../Assets/add-512.png", id=-1};
CarList.Items.Add(carAdd);

但是，最后一次操作失败，并显示以下消息:

But alas the last operation fails with this message:

在使用ItemsSource时，该操作无效.访问和修改 元素改为使用ItemsControl.ItemsSource.

Operation is not valid while ItemsSource is in use. Access and modify elements with ItemsControl.ItemsSource instead.

我还寻找了其他一些建议，但是所有示例都使用字符串和单个绑定，因此我无法弄清楚该怎么做.如果有人提出建议，将不胜感激.

I have looked for a few other suggestions but all use strings and single bindings in their examples and thus I haven't been able to figure out what exactly to do. If anyone got a suggestion it would be much appreciated.

- 谢谢.

推荐答案

您需要将该项添加到项源，并且源应该是可观察的，以便ListBox将新项考虑在内:

You need to add the item to the items source, and the source should be observable so that the ListBox takes the new item into account:

var cars = new ObservableCollection<CarModel>(CarController.GetAllCars());
CarList.ItemsSource = cars;

...

var car = new CarModel{ image_path = "/../Assets/add-512.png", id=-1};
cars.Add(car);

这篇关于WPF使用现有ItemsSource将对象添加到ListBox的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！