ASP.NET C# GridView 在分页或排序时丢失搜索选项

问题描述 投票：0回答：1

我一天中的大部分时间都在尝试通过研究来解决这个问题，但我无法找到适合我当前代码的答案。 我设置了一个由三个下拉列表和一个文本框控制的 GridView。 随着这些变化，这构建了我的 SQL 语句的 WHERE 部分，这样我就可以只提取我想要的数据。

我担心的是，其中大多数会提取数千个数据点，因此我想使用该选项来浏览 GridView 和/或按列对其进行排序。

分页和排序最初可以工作，但现在每次我尝试分页或排序时都只能得到一个空白的 GridView。

ASPX 文件：

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="TestAsset.Default" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
        <hr />
    <div>
        <a href="Upload.aspx">Manual Assets</a>
    </div>
        <hr />
    <div>
        <asp:DropDownList ID="ddlSource" runat="server" AutoPostBack="true" Width="100px" OnSelectedIndexChanged="ddlSource_SelectedIndexChanged">
            /* Removed to Protect the Innocent */
        </asp:DropDownList>
        <asp:DropDownList ID="ddlAssetType" runat="server" AutoPostBack="true" Width="150px" OnSelectedIndexChanged="ddl_SelectedIndexChanged">
            <asp:ListItem Selected="True" Text="ALL" Value="0" />
        </asp:DropDownList>
        <asp:TextBox ID="tbAsset" runat="server" AutoPostBack="false" Width="500px" OnTextChanged="ddl_SelectedIndexChanged" />
        <asp:DropDownList ID="ddlSSP" runat="server" AutoPostBack="true" Width="250px" OnSelectedIndexChanged="ddl_SelectedIndexChanged">
            <asp:ListItem Selected="True" Text="ALL" Value="0" />
        </asp:DropDownList>
    </div>
        <hr />
    <div>
        <asp:GridView ID="gvAllAssets" runat="server" AllowPaging="True" AllowSorting="True" AutoGenerateColumns="False" CellPadding="4" ForeColor="#333333" GridLines="Vertical" PageSize="25" OnPageIndexChanging="gvAllAssets_PageIndexChanging" OnSorting="gvAllAssets_Sorting">
            <AlternatingRowStyle BackColor="White" ForeColor="#284775" />
            <EditRowStyle BackColor="#999999" />
            <EmptyDataTemplate>No Data Found</EmptyDataTemplate>
            <FooterStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" />
            <HeaderStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" />
            <PagerStyle BackColor="#284775" ForeColor="White" HorizontalAlign="Center" />
            <RowStyle BackColor="#F7F6F3" ForeColor="#333333" />
            <SelectedRowStyle BackColor="#E2DED6" Font-Bold="True" ForeColor="#333333" />
            <SortedAscendingCellStyle BackColor="#E9E7E2" />
            <SortedAscendingHeaderStyle BackColor="#506C8C" />
            <SortedDescendingCellStyle BackColor="#FFFDF8" />
            <SortedDescendingHeaderStyle BackColor="#6F8DAE" />
            <Columns>
                <asp:BoundField DataField="SOURCENAME" HeaderText="Source" InsertVisible="false" ReadOnly="true" SortExpression="SOURCENAME">
                    <ItemStyle Width="100px" Wrap="false" />
                </asp:BoundField>
                <asp:BoundField DataField="ASSETNAME" HeaderText="Asset Type" InsertVisible="false" ReadOnly="true" SortExpression="ASSETNAME">
                    <ItemStyle Width="150px" Wrap="false" />
                </asp:BoundField>
                <asp:BoundField DataField="ASSET" HeaderText="Asset" InsertVisible="false" ReadOnly="true" SortExpression="ASSET">
                    <ItemStyle Width="500px" Wrap="false" />
                </asp:BoundField>
                <asp:BoundField DataField="SSP" HeaderText="System Security Plan" InsertVisible="false" ReadOnly="true" SortExpression="SSP">
                    <ItemStyle Width="250px" Wrap="false" />
                </asp:BoundField>
                <asp:BoundField DataField="LAST_UPDATED" HeaderText="Last Updated" InsertVisible="false" ReadOnly="true" SortExpression="LAST_UPDATED">
                    <ItemStyle Width="250px" Wrap="false" />
                </asp:BoundField>
            </Columns>
        </asp:GridView>

        <asp:SqlDataSource ID="dsAllAssets" runat="server" ConnectionString="<%$ ConnectionStrings:TestAssetConnectionString %>" />
    </div>
        <hr />
    <div>
        <asp:Label ID="lblSQLStatement" runat="server" />
    </div>
        <hr />
    </form>
</body>
</html>

文件背后的代码：

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace TestAsset
{
public partial class Default : System.Web.UI.Page
{
    private string strWhere = String.Empty;

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            ddlSource_SelectedIndexChanged(this, EventArgs.Empty);
        }
    }

    protected void ddlSource_SelectedIndexChanged(object sender, EventArgs e)
    {
        strWhere = String.Empty;

        ddl_SelectedIndexChanged(sender, e);

        Update_DropdownLists(ddlAssetType, "ASSETID", "ASSETNAME");
        Update_DropdownLists(ddlSSP, "DENSE_RANK() OVER (ORDER BY SSP) AS Row", "SSP");
    }

    protected void ddl_SelectedIndexChanged(object sender, EventArgs e)
    {
        strWhere = String.Empty;

        if (ddlSource.SelectedValue != "0")
        {
            if (strWhere == String.Empty)
            {
                strWhere = "WHERE SDBs.SOURCE = " + ddlSource.SelectedValue;
            }
            else
            {
                strWhere = strWhere + " AND SDBs.SOURCE = " + ddlSource.SelectedValue;
            }
        }

        if (ddlAssetType.SelectedValue != "0")
        {
            if (strWhere == String.Empty)
            {
                strWhere = "WHERE Assets.ASSET_TYPE = " + ddlAssetType.SelectedValue;
            }
            else
            {
                strWhere = strWhere + " AND Assets.ASSET_TYPE = " + ddlAssetType.SelectedValue;
            }
        }

        if (tbAsset.Text != "")
        {
            if (strWhere == String.Empty)
            {
                strWhere = "WHERE Assets.ASSET LIKE '%" + tbAsset.Text + "%'";
            }
            else
            {
                strWhere = strWhere + " AND Assets.ASSET LIKE '%" + tbAsset.Text + "%'";
            }
        }

        if (ddlSSP.SelectedValue != "0")
        {
            if (strWhere == String.Empty)
            {
                strWhere = "WHERE Assets.SSP = '" + ddlSSP.SelectedItem + "'";
            }
            else
            {
                strWhere = strWhere + " AND Assets.SSP = '" + ddlSSP.SelectedItem + "'";
            }
        }

        Update_GridView();
    }

    protected void Update_GridView()
    {
        string selectStatement =
            "SELECT " +
                "SDBNames.SOURCENAME AS 'SOURCENAME', " +
                "AssetNames.ASSETNAME AS 'ASSETNAME', " +
                "Assets.ASSET AS 'ASSET', " +
                "Assets.SSP AS 'SSP', " +
                "SDBs.LAST_UPDATED AS 'LAST_UPDATED' " +
            "FROM " +
                "Assets " +
            "INNER JOIN AssetNames " +
                "ON Assets.ASSET_TYPE = AssetNames.ASSETID " +
            "INNER JOIN SDBs " +
                "ON Assets.SDBID = SDBs.ID " +
            "INNER JOIN SDBNames " +
                "ON SDBs.SOURCE = SDBNames.SOURCEID " +
            strWhere + " ;";

        lblSQLStatement.Text = selectStatement;

        dsAllAssets.SelectCommand = selectStatement;
        DataView dv = (DataView)dsAllAssets.Select(DataSourceSelectArguments.Empty);
        DataTable dt = dv.ToTable();

        dsAllAssets.DataBind();

        if (dt.Rows.Count > 0)
        {
            gvAllAssets.DataSourceID = "dsAllAssets";
            gvAllAssets.DataBind();
        }
        else
        {
            gvAllAssets.DataSourceID = "";
            ShowNoResultFound(dt, gvAllAssets);
            gvAllAssets.Rows[0].Cells[0].Width = 1250;
        }
    }

    protected void Update_DropdownLists(DropDownList ddl, string valueField, string textField)
    {
        string modifiedValue;

        if (valueField.Contains(" AS "))
        {
            modifiedValue = valueField.Split(' ').Last();
        }
        else
        {
            modifiedValue = valueField;
        }

        string strSSPCommand = "" +
            "SELECT DISTINCT " +
                valueField + ", " +
                textField + " " +
            "FROM " +
                "Assets " +
            "INNER JOIN AssetNames " +
                "ON Assets.ASSET_TYPE = AssetNames.ASSETID " +
            "INNER JOIN SDBs " +
                "ON Assets.SDBID = SDBs.ID " +
            "INNER JOIN SDBNames " +
                "ON SDBs.SOURCE = SDBNames.SOURCEID " +
            strWhere + " " +
            "ORDER BY " + modifiedValue + " ;";

        SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["TestAssetConnectionString"].ConnectionString);
        SqlCommand cmd = new SqlCommand(strSSPCommand, con);
        SqlDataAdapter da = new SqlDataAdapter(cmd);
        DataTable dt = new DataTable();
        da.Fill(dt);

        ddl.DataValueField = modifiedValue;
        ddl.DataTextField = textField;
        ddl.DataSource = dt;
        ddl.DataBind();
        ddl.Items.Insert(0, new ListItem("ALL", "0"));
    }

    protected void ShowNoResultFound(DataTable source, GridView target)
    {
        source.Rows.Add(source.NewRow());

        target.DataSource = source;
        target.DataBind();

        int columnsCount = target.Columns.Count;
        target.Rows[0].Cells.Clear();
        target.Rows[0].Cells.Add(new TableCell());

        target.Rows[0].Cells[0].ColumnSpan = columnsCount;
        target.Rows[0].Cells[0].ForeColor = System.Drawing.Color.Red;
        target.Rows[0].Cells[0].Font.Bold = true;
        target.Rows[0].Cells[0].HorizontalAlign = HorizontalAlign.Center;
        target.Rows[0].Cells[0].Text = "NO RESULTS FOUND!";
    }

    protected void gvAllAssets_PageIndexChanging(object sender, GridViewPageEventArgs e)
    {
        gvAllAssets.PageIndex = e.NewPageIndex;
        gvAllAssets.DataBind();
    }

    protected void gvAllAssets_Sorting(object sender, GridViewSortEventArgs e)
    {
        gvAllAssets.Sort(e.SortExpression, e.SortDirection);
        gvAllAssets.DataBind();
    }


}
}

编辑2016年4月11日

我现在承认，我在 ASP.net 方面并不是最好的，但有人告诉我我需要做一些“东西”来显示我们在数据库中拥有的内容。 我对搜索选项不太热心，并花了一段时间才使其正常工作。 然后我继续恢复代码的备份副本，它再次可以进行搜索、分页和排序...因为我再次在 HTML 代码中设置了 DataSourceID，我最初将其取出，以便它会显示一些有趣的内容如果没有显示数据。 所以暂时把它留在那里并继续前进！

c# asp.net sorting gridview pagination
1个回答
0
投票

首先要尝试的是，使用 GridView 的 

.DataSource
属性，而不是 
.DataSourceID
。 提供 
DataSourceID
会导致在页面生命周期期间发生某些自动绑定操作。 由于您尝试通过特定输入事件自行管理数据绑定，因此您不希望调用其他数据绑定。

而且——你真的让自己的事情变得更加困难。 当您尝试通过用户输入减少数据集时，存储过程的效果要好得多。更好地利用 SqlDataSource 的全部功能来接受 WebControls 作为输入参数，例如：

    <asp:SqlDataSource ID="dsAllAssets" runat="server" ConnectionString="<%$ ConnectionStrings:TestAssetConnectionString %>" 
        SelectCommand="sp_SomeProcedureYouCreate" 
        SelectCommandType="StoredProcedure">
      <SelectParameters>
        <asp:ControlParameter Name="sp_var_1" ControlID="ddlAssetType" PropertyName="SelectedValue" Type="Int32" />
        <asp:ControlParameter Name="sp_var_2" ControlID="tbAsset" PropertyName="Text" Type="String" />
        <asp:ControlParameter Name="sp_var_3" ControlID="ddlSSP" PropertyName="SelectedValue" Type="Int32" />
      </SelectParameters>
    </asp:SqlDataSource>

这样你可以这样设置：

    <asp:GridView ID="gvAllAssets" runat="server" DataSourceID="dsAllAssets" ... />

将输入 

DropDownList
和 
TextBox
控件设置为在更改后回发以重新绑定。 或者设置一个按钮，仅在用户做出输入选择后回发一次

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