Telerik UI for WinForms擁有適用Windows Forms的110多個令人驚嘆的UI控件，所有的UI for WinForms控件都具有完整的主題支持，可以輕松地幫助開發人員在桌面和平板電腦應用程序提供一致美觀的下一代用戶體驗。

Telerik UI for WinForms組件為可視化任何類型的數據提供了非常豐富的UI控件，其中RadGridView是最常用的數據組件。在上文中（點擊這里回顧>>），我們主要介紹了如何綁定到DataTable、綁定到JSON、綁定到CSV等，本文繼續介紹如何層次結構中的多個子選項卡、嵌套多級層次結構等。

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層次結構中的多個子選項卡

每個GridViewTemplate都有一個Templates屬性，用于存儲其各自的子層次結構級別。因此，可以在同一層次結構級別上添加盡可能多的子模板。

現在，我們將在Products選項卡旁邊添加第二個選項卡，其中包含訂單：

DataTable ordersTable = new DataTable();
ordersTable.Columns.Add("OrderID", typeof(int));
ordersTable.Columns.Add("CategoryID", typeof(int));
ordersTable.Columns.Add("OrderDate", typeof(DateTime));
for (int i = 0; i < 30; i++)
{
ordersTable.Rows.Add(i, rand.Next(0, 5), DateTime.Now.AddDays(-1 * i));
}

GridViewTemplate ordersLevel = new GridViewTemplate();
ordersLevel.DataSource = ordersTable;
ordersLevel.Caption = "Orders";
ordersLevel.AutoSizeColumnsMode = GridViewAutoSizeColumnsMode.Fill;
this.radGridView1.MasterTemplate.Templates.Add(ordersLevel);

GridViewRelation relationOrders = new GridViewRelation(radGridView1.MasterTemplate);
relationOrders.ChildTemplate = ordersLevel;
relationOrders.RelationName = "CategoriesOrders";
relationOrders.ParentColumnNames.Add("CategoryID");
relationOrders.ChildColumnNames.Add("CategoryID");
this.radGridView1.Relations.Add(relationOrders);

嵌套多級層次結構

以類似的方式，我們將用必要的GridViewRelations定義嵌套的GridViewTemplates來構造三個層次結構：categories - product - orders。

Random rand = new Random();
DataTable categories = new DataTable();
categories.Columns.Add("CategoryID", typeof(int));
categories.Columns.Add("Title", typeof(string));
categories.Columns.Add("CreatedOn", typeof(DateTime));
for (int i = 0; i < 5; i++)
{
categories.Rows.Add(i, "Master" + i, DateTime.Now.AddDays(i));
}

DataTable productsTable = new DataTable();
productsTable.Columns.Add("ProductID", typeof(int));
productsTable.Columns.Add("CategoryID", typeof(int));
productsTable.Columns.Add("Name", typeof(string));
productsTable.Columns.Add("UnitPrice", typeof(decimal));
for (int i = 0; i < 30; i++)
{
productsTable.Rows.Add(i, rand.Next(0, 5), "Product" + i, 1.25 * i);
}

this.radGridView1.MasterTemplate.DataSource = categories;
this.radGridView1.MasterTemplate.AutoSizeColumnsMode = GridViewAutoSizeColumnsMode.Fill;

GridViewTemplate productsLevel = new GridViewTemplate();
productsLevel.DataSource = productsTable;
productsLevel.Caption = "Products";
productsLevel.AutoSizeColumnsMode = GridViewAutoSizeColumnsMode.Fill;
this.radGridView1.MasterTemplate.Templates.Add(productsLevel);

GridViewRelation relation = new GridViewRelation(radGridView1.MasterTemplate);
relation.ChildTemplate = productsLevel;
relation.RelationName = "CategoriesProducts";
relation.ParentColumnNames.Add("CategoryID");
relation.ChildColumnNames.Add("CategoryID");
this.radGridView1.Relations.Add(relation);

DataTable ordersTable = new DataTable();
ordersTable.Columns.Add("OrderID", typeof(int));
ordersTable.Columns.Add("ProductID", typeof(int));
ordersTable.Columns.Add("OrderDate", typeof(DateTime));
for (int i = 0; i < 100; i++)
{
ordersTable.Rows.Add(i, rand.Next(0, 30), DateTime.Now.AddDays(-1 * i));
}

GridViewTemplate ordersLevel = new GridViewTemplate();
ordersLevel.DataSource = ordersTable;
ordersLevel.Caption = "Orders";
ordersLevel.AutoSizeColumnsMode = GridViewAutoSizeColumnsMode.Fill;
productsLevel.Templates.Add(ordersLevel);

GridViewRelation relationOrders = new GridViewRelation(productsLevel);
relationOrders.ChildTemplate = ordersLevel;
relationOrders.RelationName = "ProductsOrders";
relationOrders.ParentColumnNames.Add("ProductID");
relationOrders.ChildColumnNames.Add("ProductID");
this.radGridView1.Relations.Add(relationOrders);

按需加載層次

在某些情況下，不需要為所有層次級別加載整個數據，這就是所謂的按需加載功能。只有在被請求時才加載層次結構級別，例如，當用戶展開父行時。

private void LoadOnDemand()
{
Random rand = new Random();
GridViewDecimalColumn idColumn = new GridViewDecimalColumn("CategoryID");
GridViewTextBoxColumn titleColumn = new GridViewTextBoxColumn("Title");
GridViewDateTimeColumn dateColumn = new GridViewDateTimeColumn("CreatedOn");
this.radGridView1.MasterTemplate.Columns.AddRange(idColumn, titleColumn, dateColumn);
this.radGridView1.MasterTemplate.AutoSizeColumnsMode = GridViewAutoSizeColumnsMode.Fill;
for (int i = 0; i < 5; i++)
{
this.radGridView1.MasterTemplate.Rows.Add(i, "Master" + i, DateTime.Now.AddDays(i));
}

GridViewTemplate productsLevel = new GridViewTemplate();
productsLevel.AutoSizeColumnsMode = GridViewAutoSizeColumnsMode.Fill;
GridViewDecimalColumn productIdColumn = new GridViewDecimalColumn("ProductID");
GridViewDecimalColumn categoryIdColumn = new GridViewDecimalColumn("CategoryID");
GridViewTextBoxColumn productNameColumn = new GridViewTextBoxColumn("Name");
GridViewDecimalColumn unitPriceColumn = new GridViewDecimalColumn("UnitPrice");
productsLevel.Columns.AddRange(productIdColumn, categoryIdColumn, productNameColumn, unitPriceColumn);
this.radGridView1.MasterTemplate.Templates.Add(productsLevel);
productsLevel.HierarchyDataProvider = new GridViewEventDataProvider(productsLevel);
this.radGridView1.RowSourceNeeded += RadGridView1_RowSourceNeeded;
}

private void RadGridView1_RowSourceNeeded(object sender, GridViewRowSourceNeededEventArgs e)
{
if (e.Template.HierarchyLevel==1)
{
for (int i = 0; i < 30; i++)
{
GridViewRowInfo row = e.Template.Rows.NewRow();
row.Cells["ProductID"].Value = i;
row.Cells["CategoryID"].Value = e.ParentRow.Cells["CategoryID"].Value;
row.Cells["Name"].Value = "Product" + row.Cells["CategoryID"].Value+"."+i;
row.Cells["UnitPrice"].Value = 1.25 * i;
e.SourceCollection.Add(row );
}
}
}

GridViewRowSourceNeededEventArgs讓開發者可以訪問相應的模板，因此如果您有幾個層次結構級別，可以通過Template.HierarchyLevel或Caption輕松區分他們。

轉換數據類型

在這篇博文的最后一部分，我們將關注一個非常微妙和重要的問題，即數據綁定和將數據記錄的字段與網格列進行映射。當數據記錄以與想要使用的RadGridView中相應列不兼容的特定類型存儲值時，我們將向您提供如何處理這種情況的技巧。

最常見的情況是在DataSource集合中存儲“YES”和“NO”，而GridViewCheckBoxColumn期望布爾值解析true/false值，考慮以下設置：

DataTable dt = new DataTable();
dt.Columns.Add("Id", typeof(int));
dt.Columns.Add("Name", typeof(string));
dt.Columns.Add("IsActive", typeof(string));
for (int i = 0; i < 20; i++)
{
dt.Rows.Add(i, "Item" + i, i % 2 == 0 ? "YES" : "NO");
}
this.radGridView1.DataSource = dt;

默認情況下，RadGridView為字符串字段生成，但是如果想用GridViewCheckBoxColumn替換默認列，則可能會丟失字段值映射，因為字符串值不能解析為布爾值。

為了處理這種情況，我們將實現一個自定義的TypeConverter類，它決定RadGridView如何識別這種類型。

public class ToggleStateConverter : TypeConverter
{
public override bool CanConvertTo(ITypeDescriptorContext context, Type destinationType)
{
return destinationType == typeof(ToggleState) || destinationType == typeof(bool);
}
public override object ConvertTo(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType)
{
if (value is string && destinationType == typeof(ToggleState))
{
string stringValue = (string)value;
switch (stringValue)
{
case "YES":
return ToggleState.On;
case "NO":
return ToggleState.Off;
default:
return ToggleState.Indeterminate;
}
}
else if (value is bool && destinationType == typeof(char))
{
bool boolValue = (bool)value;
switch (boolValue)
{
case true:
return "YES";
case false:
return "NO";
default:
return "NO";
}
}
return base.ConvertTo(context, culture, value, destinationType);
}
public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)
{
return sourceType == typeof(ToggleState) || sourceType == typeof(bool);
}
public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value)
{
ToggleState state;
bool boolValue;
if (value is ToggleState)
{
state = (ToggleState)value;
switch (state)
{
case ToggleState.On:
return "YES";
case ToggleState.Off:
return "NO";
default:
return "NO";
}
}
else if (value is bool)
{
boolValue = (bool)value;
switch (boolValue)
{
case true:
return "YES";
case false:
return "NO";
default:
return "NO";
}
}
return base.ConvertFrom(context, culture, value);
}
}

現在，對列應用轉換器：

DataTable dt = new DataTable();
dt.Columns.Add("Id", typeof(int));
dt.Columns.Add("Name", typeof(string));
dt.Columns.Add("IsActive", typeof(string));
for (int i = 0; i < 20; i++)
{
dt.Rows.Add(i, "Item" + i, i % 2 == 0 ? "YES" : "NO");
}
this.radGridView1.DataSource = dt;
this.radGridView1.Columns.Remove("IsActive");
GridViewCheckBoxColumn checkBoxColumn = new GridViewCheckBoxColumn("IsActive");
checkBoxColumn.FieldName = "IsActive";
checkBoxColumn.DataTypeConverter = new ToggleStateConverter();
checkBoxColumn.EditMode = EditMode.OnValueChange;
this.radGridView1.Columns.Add(checkBoxColumn);

使用TypeConverter的類似方法可以應用于任何網格列，并且可以轉換不同的類型。