DropdownList Update

Hi,

I have modified the sample program for Data Demo. I've used ASP.NET AJAX....I have a dropdownlist and a gridview inside an updatepanel. Also, im connected thru a objectdatasource. the dropdownlist gets value from objectdatasource1. The value comes from a distinct state from the author table while the gridview is connected to objectdatasource2. The value for objectdatasource2 comes from auther table where state = to the dropdownlist selected value.

Now what i want to achieve is that if i edit the state in the gridview my dropdownlist will be automacatically refresh. I tried adding <asp:AsyncPostBackTriggerControlID="GridView1"EventName="SelectedIndexChanged"/> to the updatepanel. I was able to save the changes but the dropdownlist doesnt.

Thanks

2lits

When both the controls that cause a refresh to the updatepanel are inside it, you can use the ChildrenAsTriggers property of the UpdatePanel. Set it to True, and your Dropdownlist should be re-binding.

Thanks

The ChildrenAsTriggers was already set to true but still my dropdownlist is not re-binding...any other thoughts? thanks!

Is your updateMode on conditional basis?

Thanks

it was set to always.

Thanks

I'd say step one is to remove the UpdatePanel and see if this is working in regular postback mode. If it is, then we need to figure out what's going wrong with your UpdatePanels.

I'd want to see some code at that point... is there just one UpdatePanel on the page? Is the GridView inside it? Is the DropDownList?

Yes There is only one Update Panel. The Gridview , dropdownlist, and the sources are inside it.

here's my code :

<formid="form1"runat="server"><asp:ScriptManagerID="ScriptManager1"runat="server"/> <divtitle="My First AJAX-Enabled Data Driven Page"><asp:UpdatePanelID="UpdatePanel1"runat="server"UpdateMode="Conditional"><ContentTemplate> <asp:DropDownListID="DropDownList1"runat="server"DataSourceID="ObjectDataSource1"DataTextField="State"DataValueField="State"AutoPostBack=True></asp:DropDownList><asp:GridViewID="GridView1"runat="server"AllowPaging="True"AutoGenerateColumns="False"DataSourceID="ObjectDataSource2"AllowSorting="True"DataKeyNames="AuthorID"><Columns><asp:CommandFieldShowEditButton="True"ShowSelectButton="True"/><asp:BoundFieldDataField="AuthorID"HeaderText="AuthorID"InsertVisible="False"ReadOnly="True"SortExpression="AuthorID"/><asp:BoundFieldDataField="FirstName"HeaderText="FirstName"SortExpression="FirstName"/><asp:BoundFieldDataField="LastName"HeaderText="LastName"SortExpression="LastName"/><asp:BoundFieldDataField="City"HeaderText="City"SortExpression="City"/><asp:BoundFieldDataField="State"HeaderText="State"SortExpression="State"/><asp:BoundFieldDataField="Zip"HeaderText="Zip"SortExpression="Zip"/><asp:BoundFieldDataField="Phone"HeaderText="Phone"SortExpression="Phone"/></Columns></asp:GridView><br/> <asp:ObjectDataSourceID="ObjectDataSource2"runat="server"OldValuesParameterFormatString="{0}"SelectMethod="GetData"TypeName="DataSet2TableAdapters.SelectAuthorsTableAdapter"UpdateMethod="Update"><SelectParameters><asp:ControlParameterControlID="DropDownList1"Name="State"PropertyName="SelectedValue"Type="String"/></SelectParameters><UpdateParameters><asp:ParameterName="AuthorID"Type="Int32"/><asp:ParameterName="FirstName"Type="String"/><asp:ParameterName="LastName"Type="String"/><asp:ParameterName="City"Type="String"/><asp:ParameterName="State"Type="String"/><asp:ParameterName="Zip"Type="String"/><asp:ParameterName="Phone"Type="String"/></UpdateParameters></asp:ObjectDataSource><asp:ObjectDataSourceID="ObjectDataSource1"runat="server"OldValuesParameterFormatString="original_{0}"SelectMethod="GetDataState"TypeName="DataSet2TableAdapters.StateListTableAdapter"></asp:ObjectDataSource><br/></ContentTemplate><Triggers><asp:AsyncPostBackTriggerControlID="DropDownList1"EventName="SelectedIndexChanged"/><asp:AsyncPostBackTriggerControlID="GridView1"EventName="RowUpdated"/></Triggers></asp:UpdatePanel> </div></form>
The updatemode is set to always. I just test it to conditional.

The updatemode is set to always. I just test it to conditional.

Thanks

And what's supposed to happen to the DropDownList when you edit the GridView?

Did you try removing the UpdatePanel? I have a feeling this isn't working with regular postbacks either and doesn't really have to do with AJAX, since your UpdatePanel code looks correct.

I should be able to see the updates in the state. example if I change the state from MI to NW upon save i should be able to see NW added in the dropdownlist. It is working on the regular postback...

Steve Marx:

I have a feeling this isn't working with regular postbacks either and doesn't really have to do with AJAX, since your UpdatePanel code looks correct.

This is to do with AJAX. When the DropDownList is binded declaratively, the list wont get refreshed on the triggers of the updatepanel. You need to explicitly bind the dropdownlist in the events specified on the updatepanel. But if have you had used the same ObjectSource for both the GridView and DropDownList, then sure the list gets updated.

Since the OP is working on the same database table, one ObjectDataSource is enough and when the GridView UpdateCommand is called, the data for the DropDownList is pulled again.

Thanks

e_screw, I don't quite understand... the databinding should work exactly the same way in a regular postback and an async postback. I'm still having trouble figuring out how this can work without the UpdatePanel but fail with it.

Certainly the DropDownList has to be bound again in the event handler, but what does that have to do with AJAX?

yes..thats also my understanding. How does the updatepanel rebind the data?

Thanks so much!

Steve Marx:

... the databinding should work exactly the same way in a regular postback and an async postback. I'm still having trouble figuring out how this can work without the UpdatePanel but fail with it. Certainly the DropDownList has to be bound again in the event handler, but what does that have to do with AJAX?

I am not sure though (still learning AJAX), the DataBinding of the controls (set declaratively using DataSourceID) will be started before the PreRender event of the page and not sure if the necessary client-scripts for that will be injected into the page by AJAX. I have checked with a different ObjectDataSource (each for Dropdownlist and GridView), and there was no client-script generated for the DropDownList unless there was explicit binding. When you are using the same ObjectDataSource for both the controls, there was client-script inject for both even if there was no explicit binding.

Thanks