Items collection must be empty before
using ItemsSource.

错误？我发现的大多数解决方案都指向不合格的XAML,例如一个额外的元素等,我似乎没有.当我拿出来

ItemsSource=”{Binding Customers}”

它运行没有错误(但当然不显示我的客户列表).

客户在viewmodel中定义如此,并具有3个Customerviewmodel：

Customer[] customers = Customer.GetCustomers();
IEnumerable<Customerviewmodel> customersviewmodels = customers.Select(c => new Customerviewmodel(c));
this.Customers = new ReadOnlyCollection<Customerviewmodel>(customersviewmodels.ToArray());

有什么建议吗？

<UserControl x:Class="TestCommandSink123.View.CustomersView"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:TestCommandSink123"
    xmlns:view="clr-namespace:TestCommandSink123.View"
    xmlns:vm="clr-namespace:TestCommandSink123.viewmodel"
    xmlns:sink="clr-namespace:TestCommandSink123.CommandSinkClasses"
    sink:CommandSinkBinding.CommandSink="{Binding}"
    >

    <UserControl.CommandBindings>
        <sink:CommandSinkBinding Command="vm:Customersviewmodel.CloseAllCustomersCommand"/>
    </UserControl.CommandBindings>

    <DockPanel>
        <ItemsControl
            DockPanel.Dock="Bottom" ItemsSource="{Binding Customers}">
            <ItemsControl.ItemTemplate>
                <DataTemplate>
                    <view:CustomerView/>
                </DataTemplate>
            </ItemsControl.ItemTemplate>
            <Button
                Command="vm:Customersviewmodel.CloseAllCustomersCommand"
                Content="Close All"
                Margin="0,8"
                />
        </ItemsControl>

    </DockPanel>
</UserControl>

回答：

我确实有错误的XAML,只是忽略它,Button应该在ItemsControl之外：

<ItemsControl
    DockPanel.Dock="Bottom" ItemsSource="{Binding Customers}">
    <ItemsControl.ItemTemplate>
        <DataTemplate>
            <view:CustomerView/>
        </DataTemplate>
    </ItemsControl.ItemTemplate>
</ItemsControl>
<Button
    Command="vm:Customersviewmodel.CloseAllCustomersCommand"
    Content="Close All"
    Margin="0,8"
    />