c# - Gridview Format Field as Phone Number but some results are 4 digit extensions, how to handle? -

so displaying results sql table in gridview. fields phone numbers. specific field may normal 10 digit number, might 4 digit extension. if it's 4 digit number, want @ minimum not put 10 digit formatting on it, @ max i'd prepend , ext: followed data. here have far. not programmer visual studio wizards , google results cobbled together. assistance.

    <form id="form1" runat="server"> <div>      <asp:gridview id="gridview1" runat="server" datasourceid="sqldatasource1"   autogeneratecolumns="false">         <columns>            <asp:templatefield headertext="call destination" sortexpression="calldestination">                 <edititemtemplate>                     <asp:textbox id="textbox2" runat="server" text='<%# bind("calldestination") %>'></asp:textbox>                 </edititemtemplate>                 <itemtemplate>                     <asp:label id="label2" runat="server" text='<%# string.format("{0:(###) ###-####}",convert.toint64(databinder.eval (container.dataitem, "calldestination")))%>'></asp:label>                 </itemtemplate>             </asp:templatefield>         </columns>     </asp:gridview>     <asp:sqldatasource id="sqldatasource1" runat="server" connectionstring="<%$ connectionstrings:oncallconnectionstring %>" selectcommand="select [timestamp], [callerid], [accepted], [calldestination] [oncalllog]"></asp:sqldatasource>  </div> </form> 

you need use rowdatabound event intercept each row bound grid can determine if phone number 10 digits or 4 digits , handle each value on case-by-case basis, this:

markup:

<asp:gridview id="gridview1" runat="server" datasourceid="sqldatasource1"       autogeneratecolumns="false" onrowdatabound="gridview1_rowdatabound"> 

note: remove text='<%# string.format("{0:(###) ###-####}",convert.toint64(databinder.eval (container.dataitem, "calldestination")))%>' <asp:label> in <itemtemplate>, because format text , set text property in rowdatabound event instead of declaratively.

code-behind:

protected void gridview1_rowdatabound(object sender, gridviewroweventargs e) {     // interested in each data row, not header or footer, etc.     if(e.row.rowtype == datacontrolrowtype.datarow)     {         // find label2 control in row         lable thelabel = (label)e.row.findcontrol("label2");          // make sure control not null         if(thelabel != null)         {             // cast bound object can use extract value             datarowview rowview = (datarowview)e.row.dataitem;              // value calldestination field in data source             string calldestinationvalue = rowview["calldestination"].tostring();              // find out if calldestination 10 digits or 4 digits             if(calldestinationvalue.length == 10)             {                 thelabel.text = string.format("{0:(###) ###-####}", convert.toint64(rowview["calldestination"]));             }             if(calldestinationvalue.length == 4)             {                 thelabel.text = "ext: " + calldestinationvalue;             }         }     } }