如何将 colgroup 标签添加到 datagrid 控件,以便我可以使用 css 设置每列的样式?
我认为这个问题已在 .NET 3.5 中解决,但我找不到任何参考。 无论如何,这是一个手卷服务器控件,允许您指定
colgroup
...
public class ColGroupGridView : GridView
{
private ColGroup _ColGroup = null;
private ITemplate _ColGroupTemplate = null;
[TemplateContainer(typeof(ColGroup))]
public virtual ITemplate ColGroupTemplate
{
get { return _ColGroupTemplate; }
set { _ColGroupTemplate = value; }
}
protected override void CreateChildControls()
{
base.CreateChildControls();
_ColGroup = new ColGroup();
ColGroupTemplate.InstantiateIn(_ColGroup);
}
protected override void Render(HtmlTextWriter writer)
{
// Get the base class's output
StringWriter sw = new StringWriter();
HtmlTextWriter htw = new HtmlTextWriter(sw);
base.Render(htw);
string output = sw.ToString();
htw.Close();
sw.Close();
// Insert a <COLGROUP> element into the output
int pos = output.IndexOf("<tr");
if (pos != -1 && _ColGroup != null)
{
sw = new StringWriter();
htw = new HtmlTextWriter(sw);
_ColGroup.RenderPrivate(htw);
output = output.Insert(pos, sw.ToString());
htw.Close();
sw.Close();
}
// Output the modified markup
writer.Write(output);
}
}
internal class ColGroup : WebControl, INamingContainer
{
internal void RenderPrivate(HtmlTextWriter writer)
{
writer.Write("<colgroup>");
base.RenderContents(writer);
writer.Write("</colgroup>");
}
}
像这样使用它...
<custom:ColGroupGridView ... runat="server">
<ColGroupTemplate>
<col class="itemid" />
<col class="cover-image" />
<col class="title" />
<col class="number" />
<col class="year" />
<col class="rating" />
<col class="cgc-rating" />
<col class="description" />
</ColGroupTemplate>
<!-- Rest of stuff here... -->
</custom:ColGroupGridView>
我已经搜索了几天有关如何将 ColGroup 模板添加到 GridView 的解决方案。使用 Josh uphere 给出的答案,以及几天有关派生对象(尤其是 GridView)的阅读,我认为更新且有效的解决方案将帮助周围的人。
Imports System.ComponentModel
Imports System.Web.UI
Imports Microsoft.VisualBasic
Imports System.IO
Namespace CustomControls
<ToolboxData("<{0}:GridViewColGroup runat=server></{0}:GridViewColGroup>")> _
<System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.Demand, Name:="FullTrust"), _
ParseChildren(True)> _
Public Class GridViewColGroup
Inherits GridView
Implements INamingContainer
Private _ColGroup As ColGroup = Nothing
Private _ColGroupTemplate As ITemplate = Nothing
<Browsable(False), _
Description("The ColGroup template."), _
TemplateContainer(GetType(ColGroup)), _
PersistenceMode(PersistenceMode.InnerProperty)> _
Public Overridable Property ColGroupTemplate() As ITemplate
Get
Return _ColGroupTemplate
End Get
Set(ByVal value As ITemplate)
_ColGroupTemplate = value
End Set
End Property
<Browsable(False), _
DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)> _
Public Property ColGroup() As ColGroup
Get
Me.EnsureChildControls()
Return _ColGroup
End Get
Set(ByVal value As ColGroup)
_ColGroup = value
End Set
End Property
Protected Overrides Sub CreateChildControls()
MyBase.CreateChildControls()
_ColGroup = New ColGroup()
If Not ColGroupTemplate Is Nothing Then
ColGroupTemplate.InstantiateIn(_ColGroup)
End If
Me.Controls.Add(_ColGroup)
End Sub
Protected Overrides Sub Render(ByVal writer As HtmlTextWriter)
EnsureChildControls()
' Get the base class's output
Dim sw As New StringWriter()
Dim htw As New HtmlTextWriter(sw)
MyBase.Render(htw)
Dim output As String = sw.ToString()
htw.Close()
sw.Close()
' Insert a <COLGROUP> element into the output
Dim pos As Integer = output.IndexOf("<tr")
If pos <> -1 AndAlso _ColGroup IsNot Nothing Then
sw = New StringWriter()
htw = New HtmlTextWriter(sw)
_ColGroup.RenderPrivate(htw)
output = output.Insert(pos, sw.ToString())
htw.Close()
sw.Close()
End If
' Output the modified markup
writer.Write(output)
End Sub
End Class
<ToolboxItem(False)> _
Public Class ColGroup
Inherits WebControl
Implements INamingContainer
Friend Sub RenderPrivate(ByVal writer As HtmlTextWriter)
writer.Write("<colgroup>")
MyBase.RenderContents(writer)
writer.Write("</colgroup>")
End Sub
End Class
End Namespace
这确实为您提供了使用它的机会,正如乔希所说:
<aspcust:GridViewColGroup runat="server" ID="gridName">
<ColGroupTemplate>
<col class="some_class_1" />
<col class="some_class_2" />
...
<col class="some_class_n" />
</ColGroupTemplate>
<Columns>
...
</Columns>
</aspcust:GridViewColGroup>
如果将派生类包装到命名空间中并在 web.config 中注册它,如下所示:
<configuration>
<system.web>
<pages>
<controls>
<add tagPrefix="aspcust" namespace="CustomControls" />
</controls >
</pages >
</system.web>
</configuration>
以编程方式,您可以在 ColGroup 中添加新列,比如说 PreRender:
Protected Sub gridName_PreRender(ByVal sender As Object, ByVal e As System.EventArgs)
Dim grd As CustomControls.GridViewColGroup = sender
Dim wctrl As New WebControl(HtmlTextWriterTag.Col)
wctrl.CssClass = "some_class_m"
grd.ColGroup.Controls.Add(wctrl)
End Sub
干杯。
为了动态添加列进行一些小的更改怎么样?
/// <summary>
/// Represents a Col element.
/// </summary>
public class HtmlCol : HtmlGenericControl
{
/// <summary>
/// Default constructor.
/// </summary>
public HtmlCol()
: base("col")
{
}
}
/// <summary>
/// Collection of HtmlCols
/// </summary>
public class HtmlCols : List<HtmlCol>
{
/// <summary>
/// Default constructor.
/// </summary>
public HtmlCols()
{
}
/// <summary>
/// Adds a col to the collection.
/// </summary>
/// <returns></returns>
public HtmlCol Add()
{
var c = new HtmlCol();
base.Add(c);
return c;
}
}
/// <summary>
/// Represents a colgrpup tag element.
/// </summary>
internal class ColGroup : WebControl, INamingContainer
{
internal void RenderPrivate(HtmlTextWriter writer)
{
writer.Write("<colgroup>");
base.RenderContents(writer);
writer.Write("</colgroup>");
}
internal void RenderPrivate(HtmlTextWriter writer, HtmlCols cols)
{
writer.Write("<colgroup>");
base.RenderContents(writer);
foreach (var c in cols)
{
c.RenderControl(writer);
}
writer.Write("</colgroup>");
}
}
[ToolboxData("<{0}:PlainGrid runat=server></{0}:Table>")]
public class PlainGrid : GridView
{
private ColGroup _colGroup = null;
private ITemplate _colGroupTemplate = null;
private HtmlCols _cols = null;
[TemplateContainer(typeof(ColGroup))]
public virtual ITemplate ColGroupTemplate
{
get { return _colGroupTemplate; }
set { _colGroupTemplate = value; }
}
protected override void CreateChildControls()
{
base.CreateChildControls();
if (ColGroupTemplate != null)
{
ColGroupTemplate.InstantiateIn(_colGroup);
}
}
protected override void Render(HtmlTextWriter writer)
{
// Get the base class's output
var sw = new StringWriter();
var htw = new HtmlTextWriter(sw);
base.Render(htw);
string output = sw.ToString();
htw.Close();
sw.Close();
// Insert a <COLGROUP> element into the output
int pos = output.IndexOf("<tr");
if (pos != -1 && _colGroup != null)
{
sw = new StringWriter();
htw = new HtmlTextWriter(sw);
_colGroup.RenderPrivate(htw, _cols);
output = output.Insert(pos, sw.ToString());
htw.Close();
sw.Close();
}
// Output the modified markup
writer.Write(output);
}
/// <summary>
/// Gets/Sets col items.
/// </summary>
public HtmlCols Cols
{
get { return _cols; }
set { _cols = value; }
}
/// <summary>
/// Default constructor
/// </summary>
public PlainGrid()
{
base.AutoGenerateColumns = false;
_colGroup = new ColGroup();
_cols = new HtmlCols();
}
}
为了创建 COLGROUP 标签,我使用了 Render 方法。这种方法效果很好,因为它速度快并且字符串操作最少。我从下面的内容开始,根据需要调整宽度。如果列太窄,浏览器会展开。其作用是产生每个的最小宽度。
Protected Overrides Sub Render(ByVal writer As System.Web.UI.HtmlTextWriter)
If Not Response.IsClientConnected Then Exit Sub
writer.InnerWriter.Close()
writer.InnerWriter = New IO.StringWriter
MyBase.Render(writer)
Dim buf$ = writer.InnerWriter.ToString
Dim p As Integer = buf.IndexOf("<thead>")
If p = 0 Then
Response.Write("CANNOT FIND THEAD TAG")
Exit Sub
End If
Response.Write(buf.Substring(0, p))
Response.Write("
<colgroup>
<col style='width:100px;' />
<col style='width:100px;' />
<col style='width:100px;' />
<col style='width:100px;' />
<col style='width:100px;' />
<col style='width:100px;' />
<col style='width:100px;' />
<col style='width:100px;' />
<col style='width:100px;' />
<col style='width:100px;' />
<col style='width:100px;' />
<col style='width:100px;' />
<col style='width:100px;' />
<col style='width:100px;' />
<col style='width:100px;' />
<col style='width:100px;' />
<col style='width:100px;' />
<col style='width:100px;' />
<col style='width:100px;' />
<col style='width:100px;' />
<col style='width:100px;' />
<col style='width:100px;' />
<col style='width:100px;' />
<col style='width:100px;' />
<col style='width:100px;' />
<col style='width:100px;' />
<col style='width:100px;' />
<col style='width:100px;' />
</colgroup>
")
Response.Write(buf.Substring(p))
End Sub