如何使用gridview中的hiddenfield在按钮点击&上找到id按钮在gridview C＃之外 [英] How to find id using hiddenfield in gridview on button click & button is outside gridview C#

问题描述

如何在按钮点击&中使用Gridview中的Hiddenfield查找ID按钮在Gridview C＃之外我正在尝试，但它显示错误对象引用未设置为对象的实例。在string strhfId =（gvRow.FindControl（hfId）作为HiddenField）.Value; 
 
我尝试了不同的
 HiddenField hfId =（HiddenField）gridData.SelectedRow.Cells [0] .FindControl（hfId）; 
 
但错误相同

我尝试过：

 protected void lnkUpdate_Click（object sender，EventArgs e）
 {
 // HiddenField hfId =（HiddenField）gridData.SelectedRow。细胞[0] .FindControl（ HFID）; 
 
 
 // HiddenField strId =（（HiddenField）gridData.Rows [0] .FindControl（hfIdValue））; 
 // String value = strId.Value; 
 
 
 LinkBut​​ton btn =发送者为LinkBut​​ton; 
 GridViewRow gvRow = btn.NamingContainer as GridViewRow; 
 string strhfId =（gvRow.FindControl（hfId）as HiddenField）.Value; 
 try 
 {
 
 
 // HiddenField hfIdc =（HiddenField）gridData.SelectedRow.Cells [0] .FindControl（hfIdValue）; 
列表< SqlParameter> parameters = new List< SqlParameter> 
 {
}; 
 parameters.Add（new SqlParameter（@ P_APPLICATION_ID，strhfId））; 
 parameters.Add（new SqlParameter（@ P_APPLICATION_NAME，txtApplicationName.Text））; 
 
 parameters.Add（new SqlParameter（@ P_MODE，E））; 
 
 string strResponse = objAppFunctionModule.ExecuteNonQueryMethod（strUSP_APPLICATION_MST，parameters）; 
 
 
 PopulateGrid（）; 
 
 
} 
 
 
 catch（例外情况）
 {
 lblResponse.Text = ex.Message; 
} 
 
} 

Markup;

< asp：GridView ID =gridDatarunat =serverAutoGenerateColumns =FalseOnRowDataBound =gridData_RowDataBound
 RowStyle- Horizo​​ntalAlign =CenterShowHeaderWhenEmpty =trueOnRowCommand =gridData_RowCommand
 EmptyDataText =没有所选值的数据BackColor =WhiteBorderColor =＃c5c5c5BorderWidth =1pxWidth =100％ 
 CellPadding =4AllowPaging =True> 
< columns> 
< asp：templatefield> 
< ItemStyle /> 
< HeaderStyle CssClass =ItemStyle/> 
< headertemplate> 
< asp：CheckBox ID =chkAllclass =cbAllrunat =serveronclick =javascript：SelectAllCheckboxes1（this）; /> 
 
< itemtemplate> 
< asp：CheckBox ID =chkMultiDeleterunat =server/> 
 
 
 
< asp：TemplateField HeaderText =应用程序名称> 
< ItemStyle /> 
< HeaderStyle CssClass =ItemStyle/> 
< itemtemplate> 
< asp：Label ID =lblApplicationNamerunat =serverText ='<％＃Eval（APPLICATION_NAME）％>'> 
< asp：HiddenField runat =serverID =hfIdValue ='<％＃Eval（APPLICATION_ID）％>'> 
 
 
< asp：TemplateField HeaderText =Edit> 
< ItemStyle /> 
< HeaderStyle CssClass =ItemStyle/> 
< itemtemplate> 
< asp：LinkBut​​ton ID =lnkEditclass =btn btn-defaultCommandName =EditButtonCommandArgument ='<％＃（（GridViewRow）Container）.RowIndex +; ％>'runat =server>  编辑

解决方案

当用户从gridview中选择一行时，想法是填充你的hiddenField。

首先你应该添加SelectedIndexchanged事件在Gridview标记中：

< asp：GridView ID =GridView1runat =server
 AutoGenerateColumns =falseOnSelectedIndexChanged =OnSelectedIndexChanged> 

后面的代码应如下所示：

  protected   void  OnSelectedIndexChanged（ object  sender，EventArgs e）
 {
  //  使用列索引访问id字段：我认为你的索引是 
  //  第一列0 
  string  id = GridView1.SelectedRow.Cells [ 0 ]。文字; 
  //  或 
  / /  您可以按名称访问该字段：确保指定列 
  / /  类型（本例中的标签） 
  string  id =（GridView1。 SelectedRow.FindControl（  id） as 标签）。文字; 
  //  将值绑定到隐藏字段 
 hfId.Text = id ;  //  隐藏字段与Gridview无关，它只是一个html  
  //  标记，其中hfId为其ID  
 
} 

一旦用户点击输入按钮，你只需得到隐藏的字段值

  protected   void  lnkUpdate_Click（ object  sender，EventArgs e）
 {
  int  selectedId = Convert.toInt32（hfId.Text）;  //  这有点危险，因为// hfText值可以是非Int。更好地使用TryParse。 
} 

如果我误解了，并且隐藏字段在gridview中，之前显示的所有内容仍然有效，只需要填充一个全局变量而不是隐藏字段（当用户选择一行时），并在用户点击链接按钮时访问它。



希望它有所帮助。

更改命令参数以删除;

 CommandArgument ='<％＃（ （GridViewRow）容器）.RowIndex％>'

然后挂钩到网格的命令事件而不是链接按钮的点击事件

 protected void gridData_RowCommand（object sender，GridViewCommandEventArgs e）
 {
 GridView g =（GridView）sender; 
 
 int index = int.Parse（e.CommandArgument.ToString（））; 
 
 GridViewRow row = g.Rows [index]; 
 HiddenField hfId =（HiddenField）row.Cells [1] .FindControl（hfId）; 
} 

你可能更好地使用gridview的内置可编辑行框架。

再次无法使用相同的错误

对象引用未设置为对象的实例。

How to find id using Hiddenfield in Gridview on button click & button is outside Gridview C# I am trying but its showing error "Object reference not set to an instance of an object." on "string strhfId = (gvRow.FindControl("hfId") as HiddenField).Value;"

I have tried different too
HiddenField hfId = (HiddenField)gridData.SelectedRow.Cells[0].FindControl("hfId");

but error is same

What I have tried:

protected void lnkUpdate_Click(object sender, EventArgs e)
        {
            //HiddenField hfId = (HiddenField)gridData.SelectedRow.Cells[0].FindControl("hfId");
            
         
            //HiddenField strId = ((HiddenField)gridData.Rows[0].FindControl("hfIdValue"));
            //String value = strId.Value;
          
          
            LinkButton btn = sender as LinkButton;
            GridViewRow gvRow = btn.NamingContainer as GridViewRow;
            string strhfId = (gvRow.FindControl("hfId") as HiddenField).Value;
                try
                {
                   

                    //HiddenField hfIdc = (HiddenField)gridData.SelectedRow.Cells[0].FindControl("hfIdValue");
                    List<SqlParameter> parameters = new List<SqlParameter>
                    {
                    };
                    parameters.Add(new SqlParameter("@P_APPLICATION_ID", strhfId));
                    parameters.Add(new SqlParameter("@P_APPLICATION_NAME", txtApplicationName.Text));
                
                    parameters.Add(new SqlParameter("@P_MODE", "E"));

                    string strResponse = objAppFunctionModule.ExecuteNonQueryMethod(strUSP_APPLICATION_MST, parameters);
                 
                    
                        PopulateGrid();
                   
             
                }


                catch (Exception ex)
                {
                    lblResponse.Text = ex.Message;
                }
            
        }

Markup;

<asp:GridView ID="gridData" runat="server" AutoGenerateColumns="False" OnRowDataBound="gridData_RowDataBound"
                                        RowStyle-HorizontalAlign="Center" ShowHeaderWhenEmpty="true" OnRowCommand="gridData_RowCommand"
                                        EmptyDataText="No Data for the Selected Value" BackColor="White" BorderColor="#c5c5c5" BorderWidth="1px" Width="100%"
                                        CellPadding="4" AllowPaging="True">
                                        <columns>
                                            <asp:templatefield>
                                                <ItemStyle />
                                                <HeaderStyle CssClass="ItemStyle" />
                                                <headertemplate>
                                                    <asp:CheckBox ID="chkAll" class="cbAll" runat="server" onclick="javascript:SelectAllCheckboxes1(this);" />
                                                
                                                <itemtemplate>
                                                    <asp:CheckBox ID="chkMultiDelete" runat="server" />
                                                
                                            

                                            <asp:TemplateField HeaderText="Application Name">
                                                <ItemStyle />
                                                <HeaderStyle CssClass="ItemStyle" />
                                                <itemtemplate>
                                                    <asp:Label ID="lblApplicationName" runat="server" Text='<%#Eval("APPLICATION_NAME") %>'>
                                                    <asp:HiddenField runat="server" ID="hfId" Value='<%#Eval("APPLICATION_ID")%>'>
                                                
                                                                                 
                                            <asp:TemplateField HeaderText="Edit">
                                                <ItemStyle />
                                                <HeaderStyle CssClass="ItemStyle" />
                                                <itemtemplate>
                                                    <asp:LinkButton ID="lnkEdit" class="btn btn-default" CommandName="EditButton" CommandArgument='<%# ((GridViewRow) Container).RowIndex + ";" %>' runat="server">Edit

解决方案

Hi,

The idea is to fill your hiddenField when user select a row from the gridview.
First you should add the SelectedIndexchanged event in the Gridview Tag :

<asp:GridView ID="GridView1" runat="server"
    AutoGenerateColumns="false" OnSelectedIndexChanged = "OnSelectedIndexChanged">

you code behind should look like this :

protected void OnSelectedIndexChanged(object sender, EventArgs e)
{
    //Accessing the id field using  Column index : i supposed your index is the 
    //first column here "0"
    string id = GridView1.SelectedRow.Cells[0].Text;
    //Or
    //you can aslo access the field by its name : make sure to specify the column 
    //type (label in this example)
    string id = (GridView1.SelectedRow.FindControl("id") as Label).Text;
    //bind the value to the hidden field
    hfId.Text = id; //the hidden filed is not related to Gridview, its just a html 
    //tag with hfId as its Id 

}

once the user click on the input button, you just have to get the hidden field value

protected void lnkUpdate_Click(object sender, EventArgs e)
        {
int selectedId =  Convert.toInt32(hfId.Text); //this is a little risky since the //hfText value can be a non Int. better use a TryParse.
}

If i misunderstood, and the Hidden field is in the gridview, everything showen earlier is still valid, you just have to fill a global variable instead of the hidden field (when user select a row), and access it when the user click the linkbutton.

Hope it helps.

Change the commandargument to drop the ";"

CommandArgument='<%# ((GridViewRow) Container).RowIndex %>'

Then hook into the grid's command event rather than the link button's click event

protected void gridData_RowCommand(object sender, GridViewCommandEventArgs e)
{
    GridView g = (GridView)sender;

    int index = int.Parse(e.CommandArgument.ToString());

    GridViewRow row = g.Rows[index];
    HiddenField hfId = (HiddenField) row.Cells[1].FindControl("hfId");
}

You're probably better using the gridview's inbuilt editable row framework though.

hi,
not working again the same error
"

Object reference not set to an instance of an object.

"

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