error Operator '>' is not defined for types 'User' and 'Integer' and Value of type 'User' cannot be converted to 'Integer'

Question

I have an error error Operator '>' is not defined for types 'User' and 'Integer' and Value of type 'User' cannot be converted to 'Integer'.

is there something wrong in my code?

Thanks

   Dim userid = uService.GetUserById(CInt(lblid.Text))
                If userid > 0 Then 'this line error 
                    End If


Public Function GetUserById(ByVal UserNo As Integer) As User
            Dim sql = $"SELECT  * FROM Users WHERE id = {UserNo}"
            Using _conn = New OleDbConnection(DbContext.GetOledbConnectionString())
                Return _conn.Query(Of User)(sql).FirstOrDefault()
            End Using
        End Function

Answer 1

GetUserById returns a user, if this user exists, and Nothing otherwise (because of .FirstOrDefault()).

Instead of checking the result for a user id > 0, check the result for Nothing

Dim user = uService.GetUserById(CInt(lblid.Text))
If user IsNot Nothing Then
    ' Do something with user
End If

A safer way to do this is to check whether the user input is a valid integer:

Dim userId As Integer

If Integer.TryParse(lblid.Text, userId) Then
    Dim user = uService.GetUserById(userId)
    If user IsNot Nothing Then
        ' Do something with user
    End If
End If