Question

I’m using Linq to write XML to a file and I want only sections of the XML that contain values to be written (so no empty tags). Here’s what I have so far:

    Public Class frm
        Public Type As String
        Public RowNumber As Integer
        Public Col1 As String
        Public Col2 As String
  End Class

  Dim bVisCustom2x7 As Boolean

  Dim visform = <VisitorForm>
                      <Tabs>
                           <Tab>
                                  <Type>Custom2x7</Type>
                                  <Order></Order>
                                  <Visibility><%= bVisCustom2x7.ToString %></Visibility>
                                  <%= From frm In frm_list Where frm.Type = "Custom2x7" _
                                      Select _
                                      <Row>
                                          <RowNumber><%= frm.RowNumber %></RowNumber>
                                          <Col1><%= frm.Col1 %></Col1>
                                          <Col2><%= frm.Col2 %></Col2>
                                      </Row>
                                  %>
                             </Tab>
                         <Tabs>
                  <VisitorForm>

So for example if frm.Col1 had no value stored how can I hide the Col1 tag from being written?

Thanks!
mg

Answer 1

It’s not the most elegant, but something like this would work:

<Row>
    <RowNumber><%= frm.RowNumber %></RowNumber>
    <%= If(Not String.IsNullOrEmpty(frm.Col1), <Col1><%= frm.Col1 %></Col1>, Nothing) %>
    <Col2><%= frm.Col2 %></Col2>
</Row>

The idea being that you can always put a <%= => expression nugget that returns either an XElement or Nothing, and it’ll only be inserted if a node was returned.