Radcombobox sorting using header template

[Gavin]

I have a radcombobox that uses a headertemplate and an itemtemplate and I would like my users to be able to sort by clicking on the text from the headertemplate.

Here is the radcombobox. It works and it's pretty simple but I can't work out how to get it to sort the items based on clicking text in the header.

                <telerik:RadComboBox ID="rcbEmp2" runat="server" Width="570px" AutoPostBack="true"
                        MarkFirstMatch="true" HighlightTemplatedItems="true" AppendDataBoundItems="true" >
                        <HeaderTemplate>
                            <ul>
                                <li>Employee</li>
                                <li>Miles</li>
                                <li>Shifts</li>
                                <li>Availability</li>
                            </ul>
                        </HeaderTemplate>
                        <ItemTemplate>
                            <ul>
                                <li><asp:Label runat="server" ID="lbEmpNameg" Text='<%# Eval("EmpFullName")%> '></asp:Label></li>
                                <li><asp:Label runat="server" ID="Label1" Text='<%# Eval("KsDistance")%> '></asp:Label></li>
                                <li><%# DataBinder.Eval(Container.DataItem, "ThisWeeksDemoCount")%></li>
                                <li><%# DataBinder.Eval(Container.DataItem, "AvailText")%></li>
                            </ul>
                        </ItemTemplate>
                    </telerik:RadComboBox>

 

Thanks in advance!

[Doncho]

Hi Gavin,

To sort the items in RadComboBox you can use one of the dedicated server-side methods

• RadComboBox1.SortItems()
• RadComboBox1.Items.Sort()

Both these methods accept one parameter of type IComparer that can be used for defining a custom sorting order based on a property of the RadComboBoxItem (Text, Value, Checked, or some Custom Attributes). 

I would suggest you review our Implement Custom Sorting article. There you can find a sample of Custom Sorting implementation where ComboBoxItems are ordered by their value.

To trigger the custom sorting in the current case, you can possibly use LinkButtons in the HeaderTemplate and handle their server-side Click event to execute the desired custom sorting procedure.

I hope this information will help you achieve the desired behavior.

Kind regards,
Doncho
Progress Telerik

[Gavin]

Thanks Doncho!

I managed to get that working server side however clicking on the link buttons causes a postback and the RadComboBox to close.

Because I can't have that happen I looked at client side sorting and I found this Sorting radcombobox in client side in UI for ASP.NET AJAX | Telerik Forums

It's pretty good  however because I'm using a HeaderTemplate and ItemTemplate 2 problems occured:-

1. I don't know how to get the values from the ItemTemplate to sort by them.

2. Because it is clearing the items then re-adding them back it loses the info in my ItemTemplate and only gives me the DataTextField. (Picture Below)

The sorting works but losing the other info in my ItemTemplate can't happen.

Is there a way that I can do it where it doesn't postback and it keeps the info in my ItemTemplate columns.

Thanks in advance!

 

Gavin

 

 

 

[Doncho]

Hi Gavin,

You can use the ItemDataBound event of the Combo to store the additional fields as custom attributes of each combo Item:

• https://docs.telerik.com/devtools/aspnet-ajax/controls/combobox/radcombobox-items/custom-attributes#radcombobox-data-binding 

Then you can use these custom attributes both to populate the combo and also to reach the specific values for each item on the client side and process them in the desired way:

• https://docs.telerik.com/devtools/aspnet-ajax/controls/combobox/radcombobox-items/custom-attributes#using-attributes-declaratively 
• https://docs.telerik.com/devtools/aspnet-ajax/controls/combobox/radcombobox-items/custom-attributes#using-custom-attributes-client-side 

[Gavin]

Hi Doncho,

When I try to use the ItemDataBound event I get the following error.

 

Here is what e.Item.DataItem is returning

{ EmployeeID = 716, EmpFullName = "Feryal Allaoui", FirstName = "Feryal", LastName = "Allaoui", TrainingSpare = false, AreaSpare = false, KsDistance = "11.06", ThisWeeksDemoCount = 0, fnIEA = 0, AvailText = "" ... }

Sorry I didn't get very far before hitting this hurdle.

 

Cheers

Gavin

[Gavin]

Hi Doncho,

After a lot of  time and research I found that the ItemDataBound event does not work for a RadComboBox when trying to retrieve the data like this DataRowView dataItem = (DataRowView)e.Item.DataItem;

I have managed to retrieve the information in the ItemDataBound event like this.

            Label lblDemoCount = item.FindControl("lblDemoCount") as Label;
            string demoCount = lblDemoCount.Text;
            if (!string.IsNullOrEmpty(demoCount))
            {
                item.Attributes["thedemoCount"] = demoCount;
            }

I have also managed to add it to an array using a loop like this

                    tempArray[i][3] = rcbItems.getItem(i).get_attributes().getAttribute("thedemoCount");

The only thing that I cannot see how to do is put it back into the RadComboBox.

I could put it into a label or anything really but can't work it out.

Here is what I'm trying

comboItem.get_attributes().setAttribute("thedemoCount", [i][3]);

comboItem.get_attributes().setAttribute("lblDemoCount", [i][3]);

Here is where I'm trying to put it 

<li class="col2g"><%# DataBinder.Eval(Container, "Attributes['thedemoCount']") %> </li>

 

Thanks in advance

Or I've tried here

<li class="col2g"><asp:Label runat="server" ID="lblDemoCount" Text='<%# DataBinder.Eval(Container.DataItem, "ThisWeeksDemoCount")%>' Visible="true"></asp:Label> </li>

[Doncho]

Hi Gavin,

In the ItemDataBound you can reach the object instance that is bound to the current ComboBox item.

For instance, If ComboBox is bound to a DataTable object, the e.Item.DataItem will return the DataRowView bound to the current item. The e.Item.DataItem is holding an object of type object and it needs to be cast to the proper type. Looking at the error message you got, it seems that the Combo is bound to a collection of anonymous objects, and casting such objects as DataRowView fails.

Instead, I would suggest you consider defining a custom class with the same properties as the one currently used in the anonymous objects. Binding a collection of strongly typed objects to the RadComboBox will allow you to use the ItemDataBound event to reach each separate object instance and cast it to its type, hence reaching the values in its properties:

E.g. RadComboBox1.DataSource is set to List<MyCustomClass> and in ItemDataBound event:

MyCustomClass dataItem = e.Item.DataItem as MyCustomClass;

To be able to provide you with more accurate assistance it would be helpful if you share the current version of the RadComboBox declaration along with all the relevant code-behind logic. That way I can have a more clear overview of the specific scenario and come up with a more specific suggestion.

[Gavin]

Hi Doncho,

I made a comment after my last one that I worked out how to get the data. I also can get it into the array using Javascript. I'm just having problems setting it.

Here is what I wrote which is also above.

Hi Doncho,

After a lot of  time and research I found that the ItemDataBound event does not work for a RadComboBox when trying to retrieve the data like this DataRowView dataItem = (DataRowView)e.Item.DataItem;

I have managed to retrieve the information in the ItemDataBound event like this.

            Label lblDemoCount = item.FindControl("lblDemoCount") as Label;
            string demoCount = lblDemoCount.Text;
            if (!string.IsNullOrEmpty(demoCount))
            {
                item.Attributes["thedemoCount"] = demoCount;
            }

I have also managed to add it to an array using a loop like this

                    tempArray[i][3] = rcbItems.getItem(i).get_attributes().getAttribute("thedemoCount");

The only thing that I cannot see how to do is put it back into the RadComboBox.

I could put it into a label or anything really but can't work it out.

Here is what I'm trying

comboItem.get_attributes().setAttribute("thedemoCount", [i][3]);

comboItem.get_attributes().setAttribute("lblDemoCount", [i][3]);

Here is where I'm trying to put it 

<li class="col2g"><%# DataBinder.Eval(Container, "Attributes['thedemoCount']") %> </li>

 

Thanks in advance

Or I've tried here

<li class="col2g"><asp:Label runat="server" ID="lblDemoCount" Text='<%# DataBinder.Eval(Container.DataItem, "ThisWeeksDemoCount")%>' Visible="true"></asp:Label> </li>

[Gavin]

Hi,

I was just wondering if there was any update on this.

I still can't see how it can be done without post back.

[Gavin]

I'm guessing this won't be answered which makes me also guess that it can't be done...

[Doncho]

Hi Gavin,

Sorry for the delay with this case.

I am attaching a sample demonstration of how you can bind multiple fields as Attributes of the ComboBox items.

Using the default server-side Sorting capabilities of the Control you can implement a custom sorting mechanism based on any of the Attributes bound to the Combo Items.

Please give it a try review the implementation and see if you can reuse the approach for the current case.

Any sorting that applies on the client side would require a custom JavaScript approach that extends the default functionalities of the control. Although such a solution could be possible, it could be quite tricky to implement and will go beyond the supported features of the Control.

To be able to run the sample you will need to add the Telerik.Web.UI.dll in the bin folder of the project.

Please let me know if any further questions come up.

Kind regards,
Doncho
Progress Telerik

[Gavin]

Thank you so much! I can't wait to give this a try!!!