Format Telephone in Column from nvarchar db

[Michael]

I have a database nvarchar field which stores the phone number.  I would like to add a column in the grid to display the formatted phone number and add a hyperlink.  Some of the cellphone fields can be null, so I am trying to check for that before converting to Int64.

The error I am getting is The best overloaded method match for 'string.IsNullOrWhiteSpace(string)' has some invalid arguments.  If I set the ItemTemplate to just Eval("CellPhone") the grid properly displays the cellphone numbers as an unformatted string.

What is the best approach here?  Once I get the basic ItemTemplate working, I was going to try to add a hyperlink so users can click on the phone number and invoke the dialing app.  ie. tel://2055551234 

<telerik:GridTemplateColumn DataField="CellPhone" FilterControlAltText="Filter CellPhoneNumber column" HeaderText="Cell Phone" UniqueName="CellPhoneNumber">

    <ItemTemplate>
        <%#  !string.IsNullOrWhiteSpace(Eval("CellPhone")) ? string.Format("{0:(###)###-####}", Convert.ToInt64(Eval("CellPhone"))) : "" %>
    </ItemTemplate>

</telerik:GridTemplateColumn>

[Viktor Tachev]

Hello Michael,

The reason for the error you are seeing is that Eval returns an object, however a string should be passed to IsNullOrWhiteSpace. In order to remedy the issue you should use the following:

string.IsNullOrWhiteSpace(Eval("CellPhone").ToString())

This way you would be able to display the phone in the correct format. Now, to enable the user to click on the number and open an external application you can use a HyperLink. Check out the following code-snippet that illustrates the approach:

<telerik:GridTemplateColumn DataField="CellPhone" HeaderText="CellPhone" UniqueName="CellPhone">
    <ItemTemplate>
        <asp:HyperLink runat="server" ID="HyperLink1"
            Text='<%#  !string.IsNullOrWhiteSpace(Eval("CellPhone").ToString()) ? string.Format("{0:(###)###-####}", Convert.ToInt64(Eval("CellPhone"))) : "" %>'
            NavigateUrl='callto:<%#  !string.IsNullOrWhiteSpace(Eval("CellPhone").ToString()) ? string.Format("{0:(###)###-####}", Convert.ToInt64(Eval("CellPhone"))) : "" %>' />

    </ItemTemplate>
</telerik:GridTemplateColumn>

Regards,
Viktor Tachev
Telerik