Silverlight ComboBox篩選器-全部顯示

Question

在帶有RIA Services的Silverlight5中，使用DomainDataSources。

我有一個綁定到DataGrid的過濾器ComboBox。

問題：如何在組合框頂部實現“全選”-當前已通過在數據庫中放置ID = 0的行並在過濾器中使用IgnoredValue =“ 0”來實現

    <riaControls:DomainDataSource.FilterDescriptors>
        <riaControls:FilterDescriptor PropertyPath="AccountTypeID" Operator="IsEqualTo" IgnoredValue="0" Value="{Binding Path=SelectedItem.AccountTypeID,
            ElementName=AccountTypeComboBox, FallbackValue=0}"  />
    </riaControls:DomainDataSource.FilterDescriptors>         
</riaControls:DomainDataSource>

<riaControls:DomainDataSource x:Name="AccountTypeDataSource" AutoLoad="True" QueryName="GetAccountTypes" PageSize="15" LoadSize="30">
    <riaControls:DomainDataSource.DomainContext>
        <domain:xxxDomainContext />
    </riaControls:DomainDataSource.DomainContext>
</riaControls:DomainDataSource>

想要在將數據加載到ComboBox中之后手動添加“顯示全部代碼”

編輯感謝下面的馬丁，我像這樣工作：

private xxxDomainContext xxxDomainContext;

    public MainPage()
    {
        InitializeComponent();

        // Load up the AccountType ComboBox - instead of doing it in XAML
        // then add in the Select All via proxy class above
        xxxDomainContext = new xxxDomainContext();
        EntityQuery<AccountType> query = xxxDomainContext.GetAccountTypesQuery();
        LoadOperation loadOperation = xxxDomainContext.Load<AccountType>(query);

        // everything is async so need a callback, otherwise will get an empty collection when trying to iterate over it here
        loadOperation.Completed += AccountTypeLoadOperationCompleted;

和

 private void AccountTypeLoadOperationCompleted(object sender, System.EventArgs e)
        {
            // create new proxy class
            var listOfSelectableObjects = new List<SelectableObject<int>>();

            var selectAll = new SelectableObject<int> { Display = "Select All", KeyValue = 0};
            listOfSelectableObjects.Add(selectAll);

            // load values into new list
            foreach (var accountType in xxxDomainContext.AccountTypes)
            {
                var so = new SelectableObject<int>();
                so.Display = accountType.Description;
                so.KeyValue = accountType.AccountTypeID;
                listOfSelectableObjects.Add(so);
            }

            AccountTypeComboBox.ItemsSource = listOfSelectableObjects;
            // Set index to 0 otherwise a blank item will appear at the top and be selected
            AccountTypeComboBox.SelectedIndex = 0;
        }

Answer 1

過去，我是通過創建一個代理類來實現此目的的，例如帶有顯示，鍵和isDefault的SelectableValue，如下所示：

public class SelectableObject<K>
{
   public string Display { get; set; }
   public K KeyValue { get;set; }
   public bool IsDefaultSelection { get; set; }
}

這意味着我可以將例如要選擇的項目列表轉換為List<SelectableObject<int>> ，並可以選擇向該列表添加一個額外的項目，即Display="Select All"和IsDefault=true而不是嘗試直接綁定到列表。

希望能有所幫助。