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(fā)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(shù)據(jù)提供了非常豐富的UI控件，其中RadGridView是最常用的數(shù)據(jù)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(xù)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(xiàn)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(shù)據(jù)，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(fā)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(qū)分他們。

轉(zhuǎn)換數(shù)據(jù)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(shù)據(jù)綁定和將數(shù)據(jù)記錄的字段與網(wǎng)格列進行映射。當數(shù)據(jù)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(xiàn)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(xiàn)在，對列應用轉(zhuǎn)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(wǎng)格列，并且可以轉(zhuǎn)換不同的類型。