DevExpress WPF使用技巧教程：如何在LookUpEdit的彈出窗口中顯示TreeListView

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通過DevExpress WPF Controls，您能創(chuàng)建有著強(qiáng)大互動(dòng)功能的XAML基礎(chǔ)應(yīng)用程序，這些應(yīng)用程序?qū)Ｗ⒂诋?dāng)代客戶的需求和構(gòu)建未來新一代支持觸摸的解決方案。

遇到的問題

有以下DTO類（在WCF服務(wù)中）：

/// <summary>
/// Класс ТБК
/// </summary>
[DataContract]
public class DTOTbkInfo
{
/// <summary>
/// Код ТБК
/// </summary>
[DataMember]
public int Code { get; set; }

/// <summary>
/// Название ТБК
/// </summary>
[DataMember]
public string Name { get; set; }

/// <summary>
/// Код уровня ТБК
/// </summary>
[DataMember]
public int LevelCode { get; set; }

/// <summary>
/// Код родительского ТБК
/// </summary>
[DataMember]
public int? ParentCode
{
get => ParentTbk?.Code;
set { }
}

/// <summary>
/// Родительское ТБК
/// </summary>
public DTOTbkInfo ParentTbk { get; set; }

/// <summary>
/// Список дочерних ТБК 
/// </summary>
[DataMember]
public List<DTOTbkInfo> ChildTbkList { get; set; }

public DTOTbkInfo()
{
//empty code
}

public DTOTbkInfo(GetTbkList_Result tbk)
{
Code = tbk.tbk;
Name = tbk.name;
LevelCode = tbk.level;
}

public static DTOTbkInfo Create(GetTbkList_Result tbk) => new DTOTbkInfo(tbk);

}

在此類中，ChildTbkList屬性包含子類列表，并且ParentTbk屬性對(duì)客戶端不可用（出于服務(wù)的內(nèi)部目的），ParentCode屬性包含父記錄的代碼。

在客戶端上，使用以下數(shù)據(jù)模型：

/// <summary>
/// Класс с информацией о ТБК товара
/// </summary>
public class TbkInfo : ViewModelBase
{
/// <summary>
/// Код ТБК
/// </summary>
public int Code { get; set; }

/// <summary>
/// Название ТБК
/// </summary>
public string Name { get; set; }

/// <summary>
/// Общая информация о ТБК
/// </summary>
public string DisplayName => $"ТБК: {Code} \"{Name}\"";

public TbkInfo()
{
//empty code
}

public TbkInfo(int code, string name)
{
Code = code;
Name = name;
}

public static TbkInfo Create(int code, string name) => new TbkInfo(code, name);
}

和類：

/// <summary>
/// Класс с дополнительной информацией о ТБК товара
/// </summary>
public class TbkInfoExt : TbkInfo
{

/// <summary>
/// Номер уровня
/// </summary>
public int LevelCode { get; set; }

/// <summary>
/// Код родительского ТБК
/// </summary>
public int? ParentCode { get; set; }

/// <summary>
/// Список дочерних ТБК
/// </summary>
public List<TbkInfoExt> ChildTbkList { get; set; }

private ObservableCollection<DTOCatalogPropertyForTbk> _catalogPropertyList;

/// <summary>
/// Список свойств товара
/// </summary>
public ObservableCollection<DTOCatalogPropertyForTbk> CatalogPropertyList
{
get => _catalogPropertyList;
set
{
_catalogPropertyList = value;
OnPropertyChanged(nameof(CatalogPropertyList));
}
}

public TbkInfoExt(DTOTbkInfo tbkInfo) : base(tbkInfo.Code, tbkInfo.Name)
{
LevelCode = tbkInfo.LevelCode;
ParentCode = tbkInfo.ParentCode;

tbkInfo.ChildTbkList?.ForEach(p =>
{
if (ChildTbkList == null)
{
ChildTbkList = new List<TbkInfoExt>();
}

ChildTbkList.Add(TbkInfoExt.Create(p));
});
}

public static TbkInfoExt Create(DTOTbkInfo tbkInfo) => new TbkInfoExt(tbkInfo);
}

有以下視圖模型：

public class EditRelationPropertyTbkModel : ViewModelBase
{
private readonly IApplicationService _appService;

#region Binding properties

private ObservableCollection<TbkInfoExt> _tbkList;

/// <summary>
/// Список ТБК
/// </summary>
public ObservableCollection<TbkInfoExt> TbkList
{
get => _tbkList;
set
{
_tbkList = value;
OnPropertyChanged(nameof(TbkList));
}
}

private TbkInfoExt _currentTbk;

/// <summary>
/// Текущий ТБК
/// </summary>
public TbkInfoExt CurrentTbk
{
get => _currentTbk;
set
{
_currentTbk = value;
OnPropertyChanged(nameof(CurrentTbk));
DefinitionCatalogPropertyList();
}
}

private ObservableCollection<DTOCatalogPropertyForTbk> _catalogPropertyList;

/// <summary>
/// Список свойств
/// </summary>
public ObservableCollection<DTOCatalogPropertyForTbk> CatalogPropertyList
{
get => _catalogPropertyList;
set
{
_catalogPropertyList = value;
OnPropertyChanged(nameof(CatalogPropertyList));
}
}

#endregion

#region Commands

private RelayCommand _saveCommand;

public RelayCommand SaveCommand => _saveCommand ?? (_saveCommand = new RelayCommand(obj =>
{

}, e => true));

private RelayCommand _cancelCommand;

public RelayCommand CancelCommand => _cancelCommand ?? (_cancelCommand = new RelayCommand(obj =>
{

}));

#endregion

#region Methods

/// <summary>
/// Метод определения списка свойств
/// </summary>
private void DefinitionCatalogPropertyList()
{
using (var proxy = new ProxyCatalog())
{
var results = proxy.GetPropertyListForTbk(CurrentTbk.Code, true);

CatalogPropertyList = new ObservableCollection<DTOCatalogPropertyForTbk>(results);

}
}

#endregion

public EditRelationPropertyTbkModel()
{
//empty code
}

public EditRelationPropertyTbkModel(IApplicationService appService)
{
_appService = appService;
}

有以下視圖（部分代碼）：

<dxg:LookUpEdit ItemsSource="{Binding TbkList}" 
SelectedItem="{Binding CurrentTbk}"
DisplayMember="Name">
<dxg:LookUpEdit.StyleSettings>
<dxg:SearchLookUpEditStyleSettings/>
</dxg:LookUpEdit.StyleSettings>
<dxg:LookUpEdit.PopupContentTemplate>
<ControlTemplate>
<dxg:GridControl x:Name="PART_GridControl">
<dxg:GridControl.Columns>
<dxg:GridColumn FieldName="Code" Header="Код ТБК" />
<dxg:GridColumn FieldName="Name" Header="Название ТБК"/>
</dxg:GridControl.Columns>
<dxg:GridControl.View>
<dxg:TreeListView AutoWidth="True" 
KeyFieldName="Code" 
TreeDerivationMode="ChildNodesSelector" 
ChildNodesPath="ChildTbkList"
AllowEditing="False"/>
</dxg:GridControl.View>
</dxg:GridControl>
</ControlTemplate>
</dxg:LookUpEdit.PopupContentTemplate>
</dxg:LookUpEdit>

問題：為什么不能選擇根元素的子元素（在CurrentTbk屬性ViewModel的SET中，不執(zhí)行任何轉(zhuǎn)換），而根元素本身也可以（在CurrentTbk屬性ViewModel的SET中進(jìn)行過渡） 執(zhí)行。

解決方案：

LookUpEdit和ComboBoxEdit編輯器只能選擇其ItemsSource集合中存在的那些值。在這種情況下，此集合中不包含子項(xiàng)，因此就是發(fā)生此問題的原因。

作為解決方案，可以將LookUpEdit.ItemsSource設(shè)置為包含父項(xiàng)和子項(xiàng)的集合，然后將GridControl.ItemsSource綁定到原始的TbkList集合。

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