[Solved] Grid disappears after clicking Edit

[Iris]

I know that this question has been asked multiple times, and i have searched the forum but it's still not working for me.

Here's the background:
On my page, I have a grid and a combobox. The grid uses datatable that is created dynamically when the the user selects some value from the combo box. Initially, when the page loads, only the combobox is visible and the grid is not visible. When the user selects a group name from the combobox, RadComboBox's SelectedIndexChanged is fired and it will populate the DataTable (this datatable is initially null) based on the selected group name (I also save the selected group name in a variable on the page). This will then call Rebind() method to rebind the grid using the table, and consequently fired the NeedDataSource event. At this point, the grid is properly populated. However if I clicked the Edit button or try to filter the columns, the grid will disappear. When I try to debug this, I found that when the edit button is clicked, the DataTable is now null, hence the reason why the grid is not displayed due to the null datasource. Even the variable that holds the selected group name is also reset.

I'm stuck here. Can anyone tell me how to get around this? Why were the datatable and the variable reset even though the page is not reloaded? Is there a way to stop the program from resetting the datatable and the variables?

 Please help.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using Telerik.Web.UI;
using System.Data;

namespace Project1
{
    public partial class frmUserGroupPrivillage : System.Web.UI.Page
    {
        private DataTable table;
        private bool displayNullDataSourceErrorMessage = false;  // enable error message to
             // be hidden the first time the page is loaded
        private string groupID, groupName;
        protected void Page_Load(object sender, EventArgs e)
        {
                // reset error and status messages' visibility
                errorMessage.Visible = false;
                statusMessage.Visible = false;

                //get module authorization for the logged in user
                Authorization a = new Authorization();

                bool[] authorization = a.GetModuleAuthorization(userID, "UserGroupPrivilege");

                if (authorization != null)
                {
                    // is the user is allowed to view this page?
                    if (authorization[0])
                    {
                        //the user is allowed to view this page
                        DisplayUserContent(authorization);
                    }
                    else
                    {
                        // the user is not allowed to view this page.
                          //Hence redirect user to main page
                        Response.Redirect("Default.aspx");
                    }
                }
                else
                {
                    //unable to get authorization information
                    errorMessage.Text = a.authorizationErrorMessage;
                    errorMessage.Visible = true;
                }
        }

        //Post: display or not display add, edit and delete buttons based on user's
          // privilege level
        private void DisplayUserContent(bool[] authorization)
        {
            // should update button inside edit form to be be displayed?
            if (authorization[2])
            {
                GridColumn editColumn = RadGrid1.Columns.FindByUniqueName("EditCommandColumn");
                editColumn.Visible = true;
             }
        }

        protected void RadComboBox1_SelectedIndexChanged(object sender, Telerik.Web.UI.RadComboBoxSelectedIndexChangedEventArgs e)
        {
            displayNullDataSourceErrorMessage = true;
            errorMessage.Visible = false;
            groupID = e.Value.Trim();
            groupName =  e.Text.Trim();

            // rebind the grid if and only if the table is successfully populated
            if (PopulateTable(groupID, groupName))
            {
                RadGrid1.Rebind();

                // make the grid visible not that it has data to display
                RadGrid1.Visible = true;
            }
        }

        // pre: invoked by radgrid1 when when it found that there is no data source during data binding
        // post: returns the datasource for the grid
        protected void RadGrid1_NeedDataSource(object sender, GridNeedDataSourceEventArgs e)
        {
            if (table != null)
            {
                RadGrid1.DataSource = table;
            }
            else
            {
                // do not display the error message when the user first viewed the module
                if (displayNullDataSourceErrorMessage)
                {
                    // the data table is null
                    errorMessage.Text = "Error. Unable to get grid data source from DataTable. The User Group Privilege cannot be displayed";
                    errorMessage.Visible = true;
                    errorMessage.Focus();
                }
            }
        }

        // pre: info: asuthorization information from database.
        //      accessType: 1 to indicate view, 2 to indicate add, 3 to indicate edit, 4 to indicate delete
        // post: returns the boolen status for the view, add, edit, OR delete privilege
        private bool GetBoolStatus(string info, int accessType)
        {
            bool status = false;
            char[] c = info.ToCharArray();
            switch (accessType)
            {
                case 1:
                    {
                        // caller method wants to know the View status
                        status = (c[0] == '1');
                        break;
                    }
                case 2:
                    {
                        // caller method wants to know the View status
                        status = (c[2] == '1');
                        break;
                    }
                case 3:
                    {
                        // caller method wants to know the View status
                        status = (c[4] == '1');
                        break;
                    }
                case 4:
                    {
                        // caller method wants to know the View status
                        status = (c[6] == '1');
                        break;
                    }
                default:
                    {
                        //should not get here
                        break;
                    }
            }
            return status;
        }

        protected void RadGrid1_EditCommand(object sender, GridCommandEventArgs e)
        {
            bool b = PopulateTable(groupID, groupName);
        }

        // post : return true if the table is successfully populated
        private bool PopulateTable(string userGroupID, string userGroupName)
        {
            string query = "SELECT RTRIM(user_group_id) AS user_group_id, RTRIM(user_group) AS user_group "
                                        + "WHERE user_group_id = '" + userGroupID + "'";

            int recordCount = 0;

            db db = new db();
            if (db.Load())
            {
                // query record corresponding to the selected userID ONLY
                if (db.QuerySQL(query, ref recordCount) && recordCount == 1)
                {
                    // create a new data table
                    table = new DataTable();

                    // declare columns for table
                    table.Columns.Add("Module Name", typeof(string));
                    table.Columns.Add("View", typeof(bool));
                    table.Columns.Add("Add", typeof(bool));
                    table.Columns.Add("Edit", typeof(bool));
                    table.Columns.Add("Delete", typeof(bool));

                    // get the number of columns in "records" table
                    int tableColumnsCount = db.SqlDataSet.Tables["records"].Columns.Count;

                    //get the selected group's privilege information
                    DataRow tempRow = db.SqlDataSet.Tables["records"].Rows[0];

                    // add records to the table by iterating the tempRow
                    DataColumn tempColumn;
                    for (int i = 0; i < tableColumnsCount; i++)
                    {
                        //get the column in at position i inside table
                        tempColumn = db.SqlDataSet.Tables["records"].Columns[i];

                        // get the COLUMN NAME for tempColumn DEBUG
                        string moduleInfo = tempColumn.ColumnName.Trim();

                        switch (moduleInfo)
                        {
                            case "user_group":
                                {
                                    // do nothing
                                    break;
                                }
                            case "user_group_id":
                                {
                                    // do nothing
                                    break;
                                }
                            default:
                                {
                                    // variables to hold the privilage information in bool type
                                    bool viewStatus = false;            //dummy default value because the compiler refused to compile
                                    bool addStatus = false;             //dummy default value because the compiler refused to compile
                                    bool editStatus = false;            //dummy default value because the compiler refused to compile
                                    bool deleteStatus = false;          //dummy default value because the compiler refused to compile

                                    // switch based on the COLUMN NAME for the columns with 0 is set to indicate true
                                    if (moduleInfo.Equals("reconcile") || moduleInfo.Equals("report") || moduleInfo.Equals("admin")))
                                    {
                                        // get the value in tempRow at column position i. Set status to true if the value is "0"
                                        viewStatus = "0".Equals(tempRow[tempColumn].ToString().Trim());
                                    }

                                    // switch based on the COLUMN NAME for the columns with 1 is set to indicate true
                                    if (moduleInfo.Equals("SpeedKey") || moduleInfo.Equals("WebReports"))
                                    {
                                        // get the value in the cell at tempRow and tempColumn. Set status to true if the value is "1"
                                        string info = tempRow[tempColumn].ToString().Trim();
                                        viewStatus = GetBoolStatus(info, 1);
                                        addStatus = GetBoolStatus(info, 2);
                                        editStatus = GetBoolStatus(info, 3);
                                        deleteStatus = GetBoolStatus(info, 4);
                                    }

                                    //add a new row to table
                                    table.Rows.Add(moduleInfo, viewStatus, addStatus, editStatus, deleteStatus);
                                    break;
                                }
                        }
                    }
                    return true;
                }
                else
                {
                    //either the connection cannot be opened or there is more than one record returned
                    if (recordCount == 1 || recordCount == 0)
                    {
                        //connection could not be opened
                        errorMessage.Text = db.LastError;
                        errorMessage.Visible = true;
                        errorMessage.Focus();
                    }
                    else
                    {
                        // there is more than one record returned
                        errorMessage.Text = "Error. There is more than one privilege information for UserGroup " + userGroupName + ". "
                                                + "Please ensure that there is only one privilege information per user group.";
                        errorMessage.Visible = true;
                        errorMessage.Focus();
                    }
                }
                return false;
            }
            else
            {
                // cannot load db
                errorMessage.Text = db.LastError;
                errorMessage.Visible = true;
                errorMessage.Focus();
                return false;
            }
        }
    }
}

<%@ Page Title="" Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true" CodeBehind="frmUserGroupPrivilege.aspx.cs" Inherits="Project1.frmUserGroupPrivillage" %>
<asp:Content ID="Content1" ContentPlaceHolderID="head" runat="server">
    <style type="text/css">
        .style1
        {
            width: 98%;
        }
    </style>
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="Title" runat="server">
    User Group Privilege Management
</asp:Content>
<asp:Content ID="Content3" ContentPlaceHolderID="MainContent" runat="server">
    <telerik:RadAjaxManager ID="RadAjaxManager1" runat="server">
        <AjaxSettings>
            <telerik:AjaxSetting AjaxControlID="RadComboBox1">
                <UpdatedControls>
                    <telerik:AjaxUpdatedControl ControlID="errorMessage" />
                    <telerik:AjaxUpdatedControl ControlID="RadComboBox1" />
                    <telerik:AjaxUpdatedControl ControlID="statusMessage" />
                    <telerik:AjaxUpdatedControl ControlID="Label1" />
                    <telerik:AjaxUpdatedControl ControlID="Label2" />
                    <telerik:AjaxUpdatedControl ControlID="RadGrid1" />
                </UpdatedControls>
            </telerik:AjaxSetting>
            <telerik:AjaxSetting AjaxControlID="RadGrid1">
                <UpdatedControls>
                    <telerik:AjaxUpdatedControl ControlID="errorMessage" />
                    <telerik:AjaxUpdatedControl ControlID="statusMessage" />
                    <telerik:AjaxUpdatedControl ControlID="Label1" />
                    <telerik:AjaxUpdatedControl ControlID="Label2" />
                    <telerik:AjaxUpdatedControl ControlID="RadGrid1" />
                </UpdatedControls>
            </telerik:AjaxSetting>
        </AjaxSettings>
    </telerik:RadAjaxManager>
<br />

    <table align="center" class="style1">
        <tr>
            <td>
            <asp:Label ID="errorMessage" runat="server" Text="Error Message" Visible="False"
                    CssClass="frmElement_ErrorText"></asp:Label>
                 <br />
                To begin, please select a user group from the combo box below:<br />
                 <br />

                 <telerik:RadComboBox ID="RadComboBox1" Runat="server"
                    EmptyMessage="Select User Group to be viewed" Skin="Vista"
                    DataSourceID="GroupNameDataSource" DataTextField="user_group"
                    DataValueField="user_group_id"
                    onselectedindexchanged="RadComboBox1_SelectedIndexChanged"
                    AutoPostBack="True" Width="250px">
                </telerik:RadComboBox>

<br />
                 <br />
                <telerik:RadGrid ID="RadGrid1" runat="server" CellSpacing="0" GridLines="None"
                    Skin="Vista" onneeddatasource="RadGrid1_NeedDataSource"
                    AutoGenerateEditColumn="True" oneditcommand="RadGrid1_EditCommand"
                    Visible="False">
<MasterTableView AllowFilteringByColumn="True" AllowSorting="True"
                        AutoGenerateColumns="True" AllowPaging="True" EditMode="InPlace">
<CommandItemSettings ExportToPdfText="Export to PDF"></CommandItemSettings>

<RowIndicatorColumn Visible="True" FilterControlAltText="Filter RowIndicator column">
<HeaderStyle Width="20px"></HeaderStyle>
</RowIndicatorColumn>

<ExpandCollapseColumn Visible="True" FilterControlAltText="Filter ExpandColumn column">
<HeaderStyle Width="20px"></HeaderStyle>
</ExpandCollapseColumn>

    <Columns>
        <telerik:GridEditCommandColumn ButtonType="ImageButton"
            CancelImageUrl="Images/Cancel.gif" EditImageUrl="Images/Edit.gif"
            FilterControlAltText="Filter EditCommandColumn column"
            InsertImageUrl="Images/Update.gif" UpdateImageUrl="Images/Update.gif"
            Visible="False">
            <ItemStyle HorizontalAlign="Center" Width="30px" />
        </telerik:GridEditCommandColumn>
    </Columns>

<EditFormSettings>
<EditColumn FilterControlAltText="Filter EditCommandColumn column"
        UniqueName="EditCommandColumn1"></EditColumn>
</EditFormSettings>
</MasterTableView>

<FilterMenu EnableImageSprites="False"></FilterMenu>
                </telerik:RadGrid>
                                    <br />

    <asp:Label ID="statusMessage" runat="server" ForeColor="#006600" Text="StatusMessage"
        Visible="False"></asp:Label>
                <br />

    <asp:Label ID="Label1" runat="server" Text="Label1"></asp:Label>

                <br />
                <asp:Label ID="Label2" runat="server" Text="Label2"></asp:Label>

            </td>
        </tr>
    </table>

    <asp:SqlDataSource ID="GroupNameDataSource" runat="server"
        ConnectionString="<%$ ConnectionStrings:MyConnectionString %>" SelectCommand="SELECT RTRIM(user_group_id) AS user_group_id, RTRIM(user_group) AS user_group
FROM User_Group ORDER BY (user_group) "></asp:SqlDataSource>

<br />
    </asp:Content>

[Iris]

anyone?

[Tsvetina]

Hello Iris,

You can try moving the PopulateTable method call to the NeedDataSource event. To get it working when there is no selection in the combo, you could declare two properties and save them in ViewState or Session, e.g.:

public string GroupName
{
    get
    {
        if (ViewState["GroupNameValue"] != null)
        {
            return (string)ViewState["GroupNameValue"];
        }
        else return "";
    }

    set
    {
        ViewState["GroupNameValue"] = value;
    }
}

public string GroupID
{
    get
    {
        if (ViewState["GroupIDValue"] != null)
        {
            return (string)ViewState["GroupIDValue"];
        }
        else return "";
    }

    set
    {
        ViewState["GroupIDValue"] = value;
    }
}

Then in PopulateTable add a check against the default values of the properties:

private bool PopulateTable(string userGroupId, string userGroupName){
{
    if(GroupNameValue=="" || GroupIDValue=="")
    {
        return false;
    }
}

Greetings,
Tsvetina
the Telerik team

[Iris]

I managed to solve this problem a few months back but i never get the chance to share it here, in case anyone else is having the same problem. Here's what I did:

I made the combobox to subscribe to the SelectedIndexChanged event. When the user selects an item from the combobox, I'll call the Rebind method on the radgrid. Here's the sample of my code:

// post: update the grid based on the chosen user group name
protected void RadComboBox1_SelectedIndexChanged(object sender, RadComboBoxSelectedIndexChangedEventArgs e)
{
    Session["groupChanged"] = "1";            // "1" here indicates true

    string groupID = e.Value.Trim();
    Session["groupID"] = groupID;

    // rebind the grid if and only if the table is successfully populated
    if (PopulateTable(groupID))
    {
        RadGrid1.Rebind();

        // make the grid visible now that it has data to display
        RadGrid1.Visible = true;
    }
}

PopulateTable(groupID) methods basically populate the datatable (in my case I declared the variable name to be "table". See the code in my first post in this thread for more info)

The radgrid needs to subscribe to NeedDataSource and ItemCommand event.

protected void RadGrid1_NeedDataSource(object sender, GridNeedDataSourceEventArgs e)
{
    if (table != null)
    {
        RadGrid1.DataSource = table;
    }
    else
    {
        // the data table is null
        PopulateTable(Session["groupID"].ToString());
        if (table != null)
        {
            RadGrid1.DataSource = table;
        }
    }
}

protected void RadGrid1_ItemCommand(object sender, GridCommandEventArgs e)
{
    if (Convert.ToString(e.CommandName).Equals("Edit"))
    {
        e.Item.OwnerTableView.IsItemInserted = false;
    }

    if (Session["groupID"] != null)
    {
        PopulateTable(Session["groupID"].ToString());
        if (table != null)
        {
            RadGrid1.DataSource = table;
        }
    }
    else
    {
       //Unable to display Edit/View/Insert form.
    }
}

The key here is the ItemCommand event. You'll need to repopulate the datatable and reassign the datatable to the radgrid's datasource property everytime, otherwise the grid won't be displayed due to null datasource.

RadGrid1.DataSource = table