[Solved] Expand row if child table has rows

[Venu Daroju]

Hi i was using

http://demos.telerik.com/aspnet-ajax/grid/examples/programming/detailtabledatabind/defaultcs.aspx

approach to display a grid with one child table, and data is all driven from code behind.

in the example C# code we have following code to expand first row

            protected void RadGrid1_PreRender(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
RadGrid1.MasterTableView.Items[0].Expanded = true;
RadGrid1.MasterTableView.Items[0].ChildItem.NestedTableViews[0].Items[0].Expanded = true;
}
}

Question is how do i expand rows who's child table has more than zero record in it and other rows which doesn't have any

records should not be expanded.

Please let me know... 

Thank you

Venu.

[Princy]

Hi,

Try the code snippet below to achieve the desired scenario. Here are the steps to accomplish this:

1)Wire the PreRender event of Telerik RadGrid

2)Traverse all grid items and get reference to those which are of type GridNestedViewItem

3)Verify whether their NestedTableViews collection is empty

4)If empty then prevent the Parent item from expanding

C#

protected void RadGrid1_PreRender(object sender, EventArgs e)
    {
        HideExpandColumnRecursive(RadGrid1.MasterTableView);

    }
public void HideExpandColumnRecursive(GridTableView tableView)
    {
       GridItem[] nestedViewItems = tableView.GetItems(GridItemType.NestedView);
       foreach (GridNestedViewItem nestedViewItem in nestedViewItems)
        {
            foreach (GridTableView nestedView in nestedViewItem.NestedTableViews)
            {
                if (nestedView.Items.Count == 0)
                {
                    nestedView.ParentItem.Expanded= false;
                }

                else
                {
                    nestedView.ParentItem.Expanded = true;
                }
            }
        }
    }

Thaks,

Princy

[Venu Daroju]

Thanks Princy,

But it didn't work, it colapses all rows

FYI: i just have only one table inside master table.

Thank you
Venu.

[Schlurk]

If you are using DetailTables the following should work:

            foreach (GridTableView myView in RadGrid1.MasterTableView.DetailTables)
            {
                if (myView.Items.Count == 0)
                {
                    myView.ParentItem.Expanded = false;
                }
                else
                {
                    myView.ParentItem.Expanded = true;
                }
            }

It's not the most efficient method but it works :) Also I think Princy's suggestion doesn't work because you seem to be using DetailTables while his approach uses NestedViews.

[Venu Daroju]

Hello Schlurk,

thank you for your solution, but i get following error

 

Server Error in '/' Application.

---

Object reference not set to an instance of an object.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error:

Line 108: { Line 109: Line 110: myView.ParentItem.Expanded = false;Line 111: } Line 112: else

if i comment the true part of if statement it works fine with out any error,  but it colapses all rows in the grid, which we do not want.

Please let me know thank you

Thank you
Venu.

[Radoslav]

Hi Venu,

Could you please try to set HierarchyLoadMode property to ServerBind and see if it makes any difference:

<MasterTableView DataSourceID="SqlDataSource1" HierarchyLoadMode="ServerBind" DataKeyNames="DataKeyNames" AllowMultiColumnSorting="True">

Then you could achieve the desired functionality with the code which Princy posted:

protected void RadGrid1_PreRender(object sender, EventArgs e)
    {
        HideExpandColumnRecursive(RadGrid1.MasterTableView);

    }
public void HideExpandColumnRecursive(GridTableView tableView)
    {
       GridItem[] nestedViewItems = tableView.GetItems(GridItemType.NestedView);
       foreach (GridNestedViewItem nestedViewItem in nestedViewItems)
        {
            foreach (GridTableView nestedView in nestedViewItem.NestedTableViews)
            {
                if (nestedView.Items.Count == 0)
                {
                    nestedView.ParentItem.Expanded= false;
                }

                else
                {
                    nestedView.ParentItem.Expanded = true;
                }
            }
        }
    }

The default value of the HierarchyLoadMode property is ServerOnDemand, however this property tells to the RadGrid to render only items which are expanded. If you try to count the child items of every parent item, the count will be always 0. So initially in the RadGrid.PreRender event do not exist any children elements and the RadGrid renders collapsed parent items.

Also you could check out this online documentation article which contains information about HierarchyLoadMode property:

http://www.telerik.com/help/aspnet-ajax/telerik.web.ui-telerik.web.ui.gridtableview-hierarchyloadmode.html

Additionally I am sending you a simple example that illustrate the how to achieve the desired functionality.

All the best,
Radoslav
the Telerik team

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