Question

How can I “search” through a strongly typed list for a string?

I am attempting .Contains(TheString), however it errors stating Unable to cast object of type ‘System.String’ to type ‘o7thCrawler.Typing.ImportantTyping’

Here is the code:

Public Class LinkTyping
    Public Property Url As String
    Public Property Title As String
    Public Property Content As String
End Class

If Not (_InternalUrls.Contains(_Url & _Link)) Then
    _InternalUrls.Add(New Typing.LinkTyping() With {
                                                          .Url = _Url & _Link,
                                                          .Content = Item.Value,
                                                          .Title = If(Item.Attribute("title") IsNot Nothing,
                                                                      Item.Attribute("title").Value,
                                                                      Nothing)
                                                      })
End If

Answer 1

You’re trying to shoe-horn 2 types into the same list…

What type is InternalUrls?

This:

If Not (_InternalUrls.Contains(_Url & _Link)) Then

Implies it’s an IList(Of String)

but this:

_InternalUrls.Add(New Typing.LinkTyping() With {

Then tries to add a new instance of your LinkTyping class to it…

How about something like…

Make InternalURLs be a List(Of LinkTyping)

Then

Dim MyUrl = String.Format("{0}{1}", _Url, _Link)
If Not InternalURLs.Any(function(x) x.Url = MyUrl) Then
    InternalURLs.Add(New Typing.LinkTyping() With {<Blah>})

End If

NB: The solution above assumes the URLs are going to be the same case for the purposes of matching (as does your example, assuming no overloaded comparison operator) – you may want to use a case-insensitive compare…

If Not InternalURLs.Any(function(x) String.Equals(x.Url, MyUrl, StringComparison.OrdinalIgnoreCase)) Then