Comment ajouter une balise Colgroup à ASP: DataGrid Control?

Question

Comment ajouter une balise colgroup au contrôle DataGrid pour que je puisse styliser chaque colonne en utilisant css?

Answer 1

Je pensais que cela a été traité dans .NET 3.5, mais je ne trouve aucune référence. Quoi qu'il en soit, voici un contrôle serveur roulées à la main qui vous permet de spécifier 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>"); 
    } 
} 

Utilisez comme ça ...

<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> 

Source: Jeff Prosise's Blog

Answer 2

Que diriez-vous changement mineur afin d'ajouter des cols dynamiquement?

/// <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(); 
    } 
} 

Answer 3

J'ai cherché depuis quelques jours une solution pour ajouter un template ColGroup à un GridView. En utilisant la réponse donnée par Josh Uphere, et quelques jours de lecture sur les objets dérivés, en particulier GridView, j'ai pensé qu'une solution mise à jour et efficace aiderait les gens.

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 

Cela vous offre vraiment la possibilité de l'utiliser comme Josh sais:

<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> 

si vous enroulez la classe dérivée dans un espace de noms et l'enregistrer dans le web.config comme suit:

<configuration> 
    <system.web> 
     <pages> 
      <controls> 
       <add tagPrefix="aspcust" namespace="CustomControls" /> 
      </controls > 
     </pages > 
    </system.web> 
</configuration> 

Programatically, vous pouvez ajouter une nouvelle colonne dans colgroup à, disons, 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 

Cheers.