refresh gridview after search - asp.net

Question

I have a search on a grid view which limits the results. I would like the grid view to repopulate with all entries if a. the search box is empty or b. the user hits a button to refresh.
Protected Sub btnSeach_Click(sender As Object, e As EventArgs) Handles btnSeach.Click
StaffDetailsStaffGridView.DataSourceID = ""
StaffDetailsStaffGridView.DataSource = ObjectDataSource1
StaffDetailsStaffGridView.DataBind()
If txtFnameSearch.text = " " Then
StaffDetailsStaffGridView.DataBind()
End If
End Sub
Protected Sub btnRefreshSearch_Click(sender As Object, e As EventArgs) Handles btnRefreshSearch.Click
StaffDetailsStaffGridView.DataBind()
End Sub
End Class
StaffDetailsStaffGridView.DataBind() obviously doesn't work.
how do I do this properly?

Answer 1

The best way to repopulate the GridView is by having a method specifically for binding your data and calling when needed.
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostback)
BindGrid();
}
private void BindGrid()
{
StaffDetailsStaffGridView.DataSource = ObjectDataSource1;
StaffDetailsStaffGridView.DataBind();
}
protected void btnRefreshSearch_Click(object sender, EventArgs e)
{
BindGrid();
}
protected void btnSeach_Click(object sender, EventArgs e)
{
if (!String.IsNullOrEmpty(txtFnameSearch.text))
{
BindGrid();
}
}
I'm assuming you are filtering your data directly via the ObjectDataSource.

Answer 2

You should get the datasource again and set it as the DataSource and then bind again.
Something like this
Protected Sub btnRefreshSearch_Click(sender As Object, e As EventArgs) Handles btnRefreshSearch.Click
Dim searchKey as String
searchKey =txtFnameSearch.Text.Trim()
Dim staffSearchREsults=MyService.GetSearchResults(searchKey)
StaffDetailsStaffGridView.DataSource = staffSearchREsults
StaffDetailsStaffGridView.DataBind()
End Sub
Assuming MyService.GetSearchResults method will return you a valid search result based on the search key.

Answer 3

This will not work because, after postback, gridview's datasource will be lost. So you always need to set datasource before DataBind() is called.
StaffDetailsStaffGridView.DataSource = ObjectDataSource1
StaffDetailsStaffGridView.DataBind()
You can also save ObjectDataSource1 into session and use it later for binding:
Session["MyObjectDataSource"] = ObjectDataSource1;
...
Protected Sub btnRefreshSearch_Click(sender As Object, e As EventArgs) Handles btnRefreshSearch.Click
StaffDetailsStaffGridView.DataSource = Session["MyObjectDataSource"]
StaffDetailsStaffGridView.DataBind()
End Sub

Answer 4

If you're using a declarative datasource, you can just call DataBind() again on the GridView:
StaffDetailsStaffGridView.DataBind()