始终显示FooterTemplate，即使没有数据

Question

即使DataSource为空时，是否还有一种使FooterTemplate（在GridView中）始终可见的简短方法？

Answer 1

如果您希望它始终显示，无论内容如何，​​您是否可以将footer html放在GridView之外，而不是放在FooterTemplate之内？

如果由于某种原因，这不是一个选项，那么您可以选择add an null row to your data source if it's empty或subclass the GridView & override the default behaviour。

这些是我所知道的唯一选项（虽然自从上次使用GridView以来已经有一段时间了）。

Answer 2

我也遇到过这个问题。来自Alconja的链接帮助很多（感谢Alconja），但GridView.FooterRow然后返回null。我需要它从页脚插入新记录。

这是我的最终解决方案。现在即使网格为空，也可以从页脚插入数据。

GridViewExtended.cs（App_Code文件夹中的类）：

using System; 
using System.Collections.Generic; 
using System.ComponentModel; 
using System.Text; 
using System.Web.UI; 
using System.Web.UI.WebControls; 

namespace YourNamespace 
{ 

    public class GridViewExtended : GridView 
    { 
    #region Public Properties 
    [Category("Behavior")] 
    [Themeable(true)] 
    [Bindable(BindableSupport.No)] 
    public bool ShowFooterWhenEmpty 
    { 
     get 
     { 
     if (this.ViewState["ShowFooterWhenEmpty"] == null) 
     { 
      this.ViewState["ShowFooterWhenEmpty"] = false; 
     } 

     return (bool)this.ViewState["ShowFooterWhenEmpty"]; 
     } 
     set 
     { 
     this.ViewState["ShowFooterWhenEmpty"] = value; 
     } 
    } 
    #endregion 

    private GridViewRow _footerRow2; 
    public override GridViewRow FooterRow 
    { 
     get 
     { 
     GridViewRow f = base.FooterRow; 
     if (f != null) 
      return f; 
     else 
      return _footerRow2; 
     } 
    } 

    protected override int CreateChildControls(System.Collections.IEnumerable dataSource, bool dataBinding) 
    { 
     int rows = base.CreateChildControls(dataSource, dataBinding); 

     // no data rows created, create empty table if enabled 
     if (rows == 0 && (this.ShowFooterWhenEmpty)) 
     { 
     // create the table 
     Table table = this.CreateChildTable(); 

     DataControlField[] fields; 
     if (this.AutoGenerateColumns) 
     { 
      PagedDataSource source = new PagedDataSource(); 
      source.DataSource = dataSource; 

      System.Collections.ICollection autoGeneratedColumns = this.CreateColumns(source, true); 
      fields = new DataControlField[autoGeneratedColumns.Count]; 
      autoGeneratedColumns.CopyTo(fields, 0); 
     } 
     else 
     { 
      fields = new DataControlField[this.Columns.Count]; 
      this.Columns.CopyTo(fields, 0); 
     } 

     if (this.ShowHeaderWhenEmpty) 
     { 
      // create a new header row 
      GridViewRow headerRow = base.CreateRow(-1, -1, DataControlRowType.Header, DataControlRowState.Normal); 
      this.InitializeRow(headerRow, fields); 

      // add the header row to the table 
      table.Rows.Add(headerRow); 
     } 

     // create the empty row 
     GridViewRow emptyRow = new GridViewRow(-1, -1, DataControlRowType.EmptyDataRow, DataControlRowState.Normal); 
     TableCell cell = new TableCell(); 
     cell.ColumnSpan = fields.Length; 
     cell.Width = Unit.Percentage(100); 

     // respect the precedence order if both EmptyDataTemplate 
     // and EmptyDataText are both supplied ... 
     if (this.EmptyDataTemplate != null) 
     { 
      this.EmptyDataTemplate.InstantiateIn(cell); 
     } 
     else if (!string.IsNullOrEmpty(this.EmptyDataText)) 
     { 
      cell.Controls.Add(new LiteralControl(EmptyDataText)); 
     } 

     emptyRow.Cells.Add(cell); 
     table.Rows.Add(emptyRow); 

     if (this.ShowFooterWhenEmpty) 
     { 
      // create footer row 
      _footerRow2 = base.CreateRow(-1, -1, DataControlRowType.Footer, DataControlRowState.Normal); 
      this.InitializeRow(_footerRow2, fields); 

      // add the footer to the table 
      table.Rows.Add(_footerRow2); 
     } 

     this.Controls.Clear(); 
     this.Controls.Add(table); 
     } 

     return rows; 
    } 
    } 

} 

在ASPX页面，只需添加

<%@ Register TagPrefix="YourPrefix" Namespace="YourNamespace" %> 

和替换<asp:GridView与<YourPrefix:GridViewExtended

希望它能帮助别人。

Answer 3

作为前面提到的评论者之一，RowDataBound事件不会触发页脚。我发现了另一个代码片段addresses this issue，但除了显示页脚外，它还显式创建该行（触发RowCreated事件）并绑定它（触发RowDataBound事件）。

我已经使用代码转换器将上面引用的代码转换为c＃并做了一些小的调整。我还包括了我在通过代码分解时所做的评论。 RowCreated和RowDataBound事件现在正在触发，我可以在页脚中填充下拉列表。

using System.Linq; 
    using System.Web.UI.WebControls; 
    using System.ComponentModel; 

    namespace WebUI.Controls 
    { 
     //modified from https://stackoverflow.com/questions/3437581/show-gridview-footer-on-empty-grid 
     public class GridViewExtended : GridView 
     { 

      private GridViewRow _footerRow; 
      [DefaultValue(false), Category("Appearance"), Description("Include the footer when the table is empty")] 
      public bool ShowFooterWhenEmpty { get; set; } 

      [DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden), Browsable(false)] 
      public override GridViewRow FooterRow { 
       get { 
        if ((this._footerRow == null)) { 
         this.EnsureChildControls(); 
        } 
        return this._footerRow; 
       } 
      } 

      protected override int CreateChildControls(System.Collections.IEnumerable dataSource, bool dataBinding) 
      { 
       //creates all the rows that would normally be created when instantiating the grid 
       int returnVal = base.CreateChildControls(dataSource, dataBinding); 
       //if no rows were created (i.e. returnVal == 0), and we need to show the footer row, then we need to create and bind the footer row. 
       if (returnVal == 0 && this.ShowFooterWhenEmpty) { 
        Table table = this.Controls.OfType<Table>().First<Table>(); 
        DataControlField[] dcf = new DataControlField[this.Columns.Count]; 
        this.Columns.CopyTo(dcf, 0); 
        //creates the footer row 
        this._footerRow = this.CreateRow(-1, -1, DataControlRowType.Footer, DataControlRowState.Normal, dataBinding, null, dcf, table.Rows, null); 
        if (!this.ShowFooter) { 
         _footerRow.Visible = false; 
        } 
       } 
       return returnVal; 
      } 

      private GridViewRow CreateRow(int rowIndex, int dataSourceIndex, DataControlRowType rowType, DataControlRowState rowState, bool dataBind, object dataItem, DataControlField[] fields, TableRowCollection rows, PagedDataSource pagedDataSource) 
      { 
       GridViewRow row = this.CreateRow(rowIndex, dataSourceIndex, rowType, rowState); 
       GridViewRowEventArgs e = new GridViewRowEventArgs(row); 
       if ((rowType != DataControlRowType.Pager)) { 
        this.InitializeRow(row, fields); 
       } else { 
        this.InitializePager(row, fields.Length, pagedDataSource); 
       } 
       //if the row has data, sets the data item 
       if (dataBind) { 
        row.DataItem = dataItem; 
       } 
       //Raises the RowCreated event 
       this.OnRowCreated(e); 
       //adds the row to the gridview's row collection 
       rows.Add(row); 
       //explicitly binds the data item to the row, including the footer row and raises the RowDataBound event. 
       if (dataBind) { 
        row.DataBind(); 
        this.OnRowDataBound(e); 
        row.DataItem = null; 
       } 
       return row; 
      } 

     } 

    }