Question

I am trying to check whether or not a string is exists in an xml file. If it does not exist, I have to add that string to the xml file.

My xml file looks like this:

  <Employee>
      <Emp>
        <Name id="1">   A     </Name>
        <Name id="2">   C     </Name>
        <Name id="3">   D     </Name>
       </Emp>
  </Employee>

And I want achieve:

dim str as string = "b" 
if str exists in "xmlfile"
    'do something
else
    'add string to file
end if

I am not really familiar LINQ at all but I understand that what I want to do is possible with LINQ. I have tried the following:

Dim employee = XElement.Load(someStream)
Dim emp = employee.Element("Emp")
If emp IsNot Nothing Then
    else
        'add string to xml file
End If

When I tried this I received the error: XElement is not declared.

Can any one suggest a way to do what I want in VB.NET without LINQ? Or if I have to use LINQ, can some provide an example?

I am using .net 2.0 (VB.NET)

Answer 1

What I think you want is something more like this:

Dim employeeData As XDocument
Dim employeeElements as List(Of XElement)
Dim numberOfNames as Integer = 0

employeeData = XDocument.Load(someStream)

employeeElements = (From elements In employeeData.Decendants()
                    Where (elements.Name.LocalName.ToString() = "Emp")
                    Select elements).ToList()

For Each employee In employeeElements
    If (employee.<Name>.Value = "B") Then
        numberOfNames = numberOfNames + 1
    End If
Next

If numberOfNames > 0 Then
    'Insert "B" into xml
End If

So that’s an example using XDocument and interating though like user1512185 suggested with an example LINQ expression to get a list of XElements to iterate through.

This is a modification of something I do in one of my apps. However I don’t insert into the xml so I’m not sure I can help you there.