asp.net - Set a DropDownList SelectedValue to a bound field with sometimes null value -

i have situation have gridview populated sql table editing allowed. 1 of fields, have user has select value drop down box in edit template gridview.

<asp:templatefield headertext="department" sortexpression="department">                  <edititemtemplate>                      <asp:dropdownlist id="ddleditdepartment" runat="server"                           selectedvalue='<%# bind("department") %>'>                     <asp:listitem>department 1</asp:listitem>                     <asp:listitem>department 2</asp:listitem>                     <asp:listitem>department 3</asp:listitem>                      </asp:dropdownlist>                  </edititemtemplate>                  <itemtemplate>                      <asp:label id="lbldepartment" runat="server" text='<%# bind("department") %>'></asp:label>                  </itemtemplate>             </asp:templatefield> 

if select "edit" record in field has value stored in table it, no problem. however, if select "edit" , there no value in table yet, following error

'ddleditdepartment' has selectedvalue invalid because not exist in list of items. parameter name: value 

how can account blank or null values in situation , make work?

you're binding dropdownlist field named "department" in gridview's datasource:

selectedvalue='<%# bind("department") %>' 

it's kind of hack, modify query populates department field of gridview account nulls (by coalescing them out):

select coalesce(department, "no department entered") department yourtable 

and add kind of "default" option in dropdown:

<asp:listitem>no department entered</asp:listitem>