FindControl - in ItemCommand returning a null

Question

User-1999980185 posted

Please see Code and Markup Below:  The statement string Ddesc = LblDdesc.Text; is returning null.  What am I doing incorrect.  See Code and Markup below

Code Below:

protected void ListView1_ItemCommand(object sender, ListViewCommandEventArgs e)
        {
            // FindConrol code goes here
            Label LblDdesc = ListView1.FindControl("Ddesc") as Label;
            string Ddesc = LblDdesc.Text;                              // Error Message:  LblDdesc.Text is Null

            // Determine what button was selected
            if (string.Equals(e.CommandName, "Select_Sel"))     // transfer to change page

            {
                Response.Redirect("form2_Chg.aspx");
            }                             
        }


Markup Below:

<asp:ListView ID="ListView1" runat="server" OnItemCommand="ListView1_ItemCommand">
                  
              
  <ItemTemplate>
                <tr style="color: #333333; ">
                  
                    <td>
                      <asp:linkbutton ID="Linkbutton1" runat="server"  text='Select' Commandname="Select_Sel" />                   
                   </td>

                <td>
                      <asp:label ID="DDate" runat="server"  text='<%# Eval("DDate")%>' />                   
                  </td> 
                    
                   <td>
                      <asp:label ID="Ddesc" runat="server"  text='<%# Eval("Ddesc")%>' />                   
                  </td> 

               </tr>

      </ItemTemplate>

Answer 1

User2103319870 posted

Instead of directly finding the controls from ListView, Try using CommandEventArgs to get the label control like below

 protected void ListView1_ItemCommand(object sender, ListViewCommandEventArgs e)
        {
            if (String.Equals(e.CommandName, "AddToList"))
            {
                // FindConrol code goes here
                ListViewDataItem dataItem = (ListViewDataItem)e.Item;
                Label LblDdesc = dataItem.FindControl("Ddesc") as Label;
                string Ddesc = LblDdesc.Text;                              // Error Message:  LblDdesc.Text is Null

                // Determine what button was selected
                if (string.Equals(e.CommandName, "Select_Sel"))     // transfer to change page

                {
                    Response.Redirect("form2_Chg.aspx");
                }
            }
        }

Answer 2

User-1999980185 posted

The code below get the same error message

ListViewDataItem dataItem = (ListViewDataItem)e.Item;
Label LblDdesc = ListView1.FindControl("Label2") as Label;
string Ddesc = LblDdesc.Text;

Get same error message:   Object reference not set to an instance of an object.

Answer 3

User-1171043462 posted

This I have tested.

    protected void ListView1_ItemCommand(object sender, ListViewCommandEventArgs e)
    {
        if (e.CommandName == "Select_Sel")
        {
            Label LblDdesc = e.Item.FindControl("Ddesc") as Label;
        }
    }

Answer 4

User2103319870 posted

Label LblDdesc = ListView1.FindControl("Label2") as Label;

I think you are using wrong ID for label control. Change Label2 to "Ddesc"

Try with below code

ListViewDataItem dataItem = (ListViewDataItem)e.Item;
Label LblDdesc = ListView1.FindControl("Ddesc") as Label;
string Ddesc = LblDdesc.Text;

Answer 5

User-1999980185 posted

I get the same results after the change.  Are there any examples that I can view so I can determined what I am doing incorrect?

Answer 6

User-1999980185 posted

When I change code please see error message below with new code, and markup.  Am I missing something in my markup code?

Code Below:
protected void ListView1_ItemCommand(object sender, ListViewCommandEventArgs e)
        {
            //     FindConrol code goes here
            //     Label LblDdesc = ListView1.[Convert.ToInt32].FindControl("Label2") as Label;
            //     Label LblDdesc = (Label)ListView1.FindControl("Label2") as Label;


            ListViewDataItem dataItem = (ListViewDataItem)e.Item;
            Label LblDdesc = ListView1.e.Item.FindControl("Ddesc") as Label;
            string Xxxx = LblDdesc.Text;   



Markup Below:

<asp:ListView ID="ListView1" runat="server" OnItemCommand="ListView1_ItemCommand">
                  
              
  <ItemTemplate>
                <tr style="color: #333333; ">
                  
                    <td>
                      <asp:linkbutton ID="Linkbutton1" runat="server"  text='Select' Commandname="Select_Sel" />                   
                   </td>

                <td>
                      <asp:label ID="DDate" runat="server"  text='<%# Eval("DDate")%>' />                   
                  </td> 
                                    
                   <td>
                      <asp:label ID="Ddesc" runat="server"  text='<%# Eval("Ddesc")%>' />                   
                  </td> 

               </tr>

      </ItemTemplate>


Error Below:

Severity	Code	Description	Project	File	Line	Suppression State
Error	CS1061	'ListView' does not contain a definition for 'e' and no extension method 'e' accepting a first argument of type 'ListView' could be found (are you missing a using directive or an assembly reference?)	FirstCWeb	C:\Users\Edward\documents\visual studio 2015\Projects\MyFirstCWeb_Solution\FirstCWeb\FirstCWeb_PageOne.aspx.cs	136	Active

Answer 7

User-1999980185 posted

Mudassarkhan you said you tested your answer, could you please send me a copy of the markup because I think that I am doing something incorrect in my markup.  Thank you.

Answer 8

User-1171043462 posted

 <asp:ListView ID="UsersListView" AutoPostBack="true" runat="server" OnSelectedIndexChanging="UsersListView_SelectedIndexChanging"
        OnSelectedIndexChanged="UsersListView_SelectedIndexChanged">
        <LayoutTemplate>
            <table id="itemPlaceholderContainer" runat="server" border="0" style="">
                <tr>
                    <td id="itemPlaceholder" runat="server">
                    </td>
                </tr>
            </table>
        </LayoutTemplate>
        <ItemTemplate>
            <tr id="Tr1" runat="server">
                <td>
                    <asp:LinkButton ID="UserNameLinkButton" CommandName="Select" runat="server" Text='<%# Eval("Name") %>' />
                </td>
            </tr>
        </ItemTemplate>
        <SelectedItemTemplate>
            <tr id="Tr1" runat="server" style = "background:#336699">
                <td>
                    <asp:LinkButton ID="UserNameLinkButton" CommandName="Select" runat="server" Text='<%#  Eval("Name") %>'
                        ForeColor="White" />
                </td>
            </tr>
        </SelectedItemTemplate>
    </asp:ListView>

Answer 9

User-1171043462 posted

Complete Code

 protected void Page_Load(object sender, EventArgs e)
    {
        if (!this.IsPostBack)
        {
            DataTable dt = new DataTable();
            dt.Columns.AddRange(new DataColumn[2] { new DataColumn("DDate"), new DataColumn("Ddesc") });
            dt.Rows.Add("1", "2");
            dt.Rows.Add("3", "4");
            ListView1.DataSource = dt;
            ListView1.DataBind();
        }
    }
    protected void ListView1_ItemCommand(object sender, ListViewCommandEventArgs e)
    {
        if (e.CommandName == "Select_Sel")
        {
            Label LblDdesc = e.Item.FindControl("Ddesc") as Label;
        }
    }

 <asp:ListView ID="ListView1" runat="server" OnItemCommand="ListView1_ItemCommand">
        <ItemTemplate>
            <tr style="color: #333333;">
                <td>
                    <asp:LinkButton ID="Linkbutton1" runat="server" Text='Select' CommandName="Select_Sel" />
                </td>
                <td>
                    <asp:Label ID="DDate" runat="server" Text='<%# Eval("DDate")%>' />
                </td>
                <td>
                    <asp:Label ID="Ddesc" runat="server" Text='<%# Eval("Ddesc")%>' />
                </td>
            </tr>
        </ItemTemplate>
    </asp:ListView>

Answer 10

User-1999980185 posted

Mudassarkhan and all that help.  I will review your code with mine and see what I am doing incorrect.   Thanks to all.

Answer 11

User-1171043462 posted

Can you please mark my reply too that helped as Answer for others to know which reply helped?