Hi,

 I am using a grid view with parameter defined in dropdown list. the asp code is:

<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:Pubs %>"

SelectCommand="SELECT [au_id], [au_lname], [au_fname], [state] FROM [authors] WHERE ([state] = @state)"

DeleteCommand="DELETE FROM [authors] WHERE [au_id] = @au_id">

<SelectParameters>

<asp:ControlParameter ControlID="DropDownList1" Name="state" PropertyName="SelectedValue"

Type="String" />

</SelectParameters>

<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:Pubs %>"

SelectCommand="SELECT [au_id], [au_lname], [au_fname], [state] FROM [authors] WHERE ([state] = @state)"

DeleteCommand="DELETE FROM [authors] WHERE [au_id] = @au_id">

<SelectParameters>

<asp:ControlParameter ControlID="DropDownList1" Name="state" PropertyName="SelectedValue"

Type="String" />

</SelectParameters>

</asp:SqlDataSource>

</asp:SqlDataSource>

SqlDataSource1.SelectParameters("state").DefaultValue = DropDownList1.Text

SqlDataSource1.SelectCommand = "SELECT [au_id], [au_lname], [au_fname], [state] FROM [authors] WHERE ([state] = @state)"

Any ideas how I can set the select parameters (in my VB code) to use the dropdown list I have in my page?

Thanks,

 Uzi

Check this video: http://www.asp.net/learn/videos/video-49.aspx. This explains how you should be using a Drop Down List and a GridView to filter data from a datasource (in this case a SQL Server table)

Hi Friend,

in which line did you get that error ?

could you show the line...?!

Greetings friend,

I get it in the line:

SqlDataSource1.SelectParameters("state").DefaultValue = DropDownList1.Text

Thanks,

Uzi 

I don' have an experience in sqldatasource. but i will give an idea.

Here you are getting the error "object reference not set to instance of an object"

that means you are trying to access an object whose value is null.

here , "SqlDataSource1.SelectParameters("state")" is returning "null" . so it is giving this error.

try this, SqlDataSource1.SelectParameters("@state") instead of SqlDataSource1.SelectParameters("state")

still if it is not giving the results. debug it. set a break point there,

check the values of "sqldatasource1.selectparameters" ---------> it will show the parameter collection, show that properties, it will show the count of those parameters and values in that collection. see those. you will get an idea.

Hi,

Still the same error.... 

Thansk for you help!

Uzi 

SqlDataSource1.SelectParameters("state").DefaultValue = DropDownList1.Text

SqlDataSource1.SelectCommand = "SELECT [au_id], [au_lname], [au_fname], [state] FROM [authors] WHERE ([state] = @state)"

Based on my knowledge, I don't think it would work. Since you have already configured your sqldatasource in your page markup, and have set "@state" to take the value from your DropdownList1.Selected Value, (by this:

<asp:ControlParameter ControlID="DropDownList1" Name="state" PropertyName="SelectedValue" Type="String" /> ), the parameter @state's value would be determined at run time and would be assigned value from your dropdwonlist.  You cannot change its value by setting its defaultvalue property.

Any ideas how I can set the select parameters (in my VB code) to use the dropdown list I have in my page?

I'm not a little confused on this, since I think your datasrouce.selectParameters["state"] has already used the dropdown list in your page. You don't have to write any more code in your code behind. Just bind your datasource to a displaying control, anything would be fine.

Hope my suggestion helps

The problem is here.

Since you already assigned value to ur state once in sqldatasource

And again ur assigning value to it so it is giving an error.

The solution is you declare either in the Menu based-Wizard or declare locally from scratch but don't perform operations both at the same time.

And also the method you declared is wrong.It should be as

SqlDataSource1.SelectParameters.Add("@state", DropDownList1.Text);

ok any way i think thi ssolves your problem

Mark As Answer if this solves your Problem

Further Queries Recommended

Happy Coding

Hi,

Thanks for the info. I manamged to solve it finally !!!!!!!

The solution is to add the new parameter:

And then to use it in the select parameters statement

SqlDataSource1.SelectParameters("state").DefaultValue = DropDownList1.Text

Many thnks for your help.