DataGridView use with LINQ query (MCTS 70-505 Ch 6 Lesson 6 page 321 Exercise 2 "LINQ to SQL")

Question

Option Strict Off
Imports System.Data.Linq
Imports System.Data.Linq.Mapping
<Table(Name:="Customers")> _
Public Class Customer
Dim db As New DataContext("Data Source = .\sqlexpress; Initial Catalog=Northwind; Integrated Security = true")
Dim customers As Table(Of Customer)
Private _customerID As String
<Column(IsPrimarykey:=True, storage:="_customerID")> _
Public Property CustomerID() As String
Get
Return _customerID
End Get
Set(value As String)
_customerID = value
End Set
End Property
Private _ContactName As String
<Column(Storage:="_ContactName")> _
Public Property ContactName() As String
Get
Return _ContactName
End Get
Set(value As String)
_ContactName = value
End Set
End Property
Private _CompanyName As String
<Column(Storage:="_CompanyName")> _
Public Overloads Property CompanyName() As String ' does not appear. Its a member of control base class. Shadows does not help, though it should
Get ' because the name of the column in the db happens to be the same as this property of the Control class. Overloads no good either
Return _CompanyName
End Get
Set(value As String)
_CompanyName = value
End Set
End Property
Private _Country As String
<Column(Storage:="_Country")> _
Public Property Country As String
Get
Return _Country
End Get
Set(value As String)
_Country = value
End Set
End Property
Private Sub Customer_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
' get a typed table on which to run queries
customers = db.GetTable(Of Customer)()
' query for a list of countries
Dim countriesquery As Object = From cust In customers Select cust.Country Distinct
For Each cust As Object In countriesquery ' option strict ON disallows late binding so it must be OFF (see line 1)
countryComboBox.Items.Add(cust.ToString)
Next
countryComboBox.SelectedIndex = 0
End Sub
Private Sub countryComboBox_SelectedIndexChanged(sender As Object, e As System.EventArgs) Handles countryComboBox.SelectedIndexChanged
Dim query As Object = From cust As Customer In customers _
Where cust.Country = countryComboBox.SelectedItem.ToString _
Select cust
resultsGrid.DataSource = query
End Sub
This code works as intended up to a point. It displays the countries in the comboBox as intended. Selecting a country then populates the DGV object "resultsgrid" with the customer items.  Problem is that the CompanyName column (and therefore
the CompanyName values) are ABSENT from the grid.  Clearly the "Resultsgrid.Datasource = query" statement is not working correctly. 
You can workaround the fault by replacing this statement with manually adding columns to the resultsgrid and then iterating over the query with a for each loop, adding a row on each iteration.  So the query is capturing all the data, including CompanyName. 
But it begs the question: why is the CompanyName (among all the cust items) consistently missing from the resultsgrid when the datasource property statement is used?   What is so special about CompanyName?

Answer 1

<
Column(Storage:="_CompanyName")>
PublicOverloadsPropertyCompanyName()
AsString'
doesn't appear in DGV.  It's a member of control base class.  Shadows doesn't help, though it should
Get'
because the name of the column in the db happens to be the same as this property of the Control class. Overloads no good either
Return_CompanyName
EndGet
Set(value
AsString)
            _CompanyName = value
EndSet
EndProperty
Howard