Gridview 页脚默认值缺失

Question

我有一个可以按日期搜索的网格视图。 在gridview中，如果日期的gridview为空，我手动添加页脚。 它工作正常，然后首先加载页面。

问题是： 当使用数据加载 gridview 时，页脚显示默认数据。之后，选择没有数据的日期，默认值丢失。如果我选择另一个没有数据的日期，页脚的默认值会再次出现。

我放了断点，它通过了下面的函数，值不为空，但它没有显示在页脚的标签上。

while (Dr.Read())
{
   AttendbyFooter.Text = Dr.GetValue(1).ToString();
   DepartmentFooter.Text = Dr.GetValue(4).ToString();

}

Gridview 数据绑定：

        Label AttendbyFooter = GridView1.FooterRow.FindControl("AttendbyFooter") as Label;

        //if the footer is null, do nothing. if the footer is not null, continue for other value
        if (AttendbyFooter == null)
        {

        }
        else
        {
            //set default name
            AttendbyFooter.Attributes.Add("readonly", "readonly");
            Label DepartmentFooter = GridView1.FooterRow.FindControl("DepartmentFooter") as Label;
            DepartmentFooter.Attributes.Add("readonly", "readonly");

            //create a connection to mssql server
            var Cn = new System.Data.SqlClient.SqlConnection();
            Cn.ConnectionString = ConfigurationManager.ConnectionStrings["CMOSConnectionString"].ConnectionString;

            Cn.Open();

            //create a command object from the connection
            var Cm = Cn.CreateCommand();

            //Check database using username(id number)
            Cm.CommandText = string.Format(@"Select * From Employee WHERE PassNumber='{0}'", User.Identity.Name);

            var Dr = Cm.ExecuteReader();


            while (Dr.Read())
            {
                //Name
                AttendbyFooter.Text = Dr.GetValue(1).ToString();
                DepartmentFooter.Text = Dr.GetValue(4).ToString();

            }
            Cn.Close();
        }

生成页脚（从网站复制）

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;
    }
}

}

Answer 1

尝试在页面加载后清除日期文本框。