linq query to datagridview, why do I see a column which contains numbers?

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VB

Private Sub Form1_Load(sender As Object, e As System.EventArgs) Handles Me.Load

Dim Months = {"January", "Febuary", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"}

        Dim DGView As New DataGridView
        Me.Controls.Add(DGView) 'Add datagridview
        DGView.ColumnCount = 1 ' add a column
        DGView.Columns(0).Name = "Month" 'add a column name
        DGView.Dock = DockStyle.Fill 'set dock style

        'linq query
        Dim Q = From M In Months
                   Select M

        DGView.DataSource = Months


    End Sub

when I run this code why isnt month column populated with "Months" and why do I see a column called length which is populated with numbers, which I never asked for with my qry.

-----------------------------------------------------------------------------------

Here is updated solution following suggestion to use a "Class", would like suggestions to reduce lines of code as it looks a bit long.

VB

Public Class Form1
    Public Class Year
        Public Property Months As String
    End Class

    Public Sub OrderByMonth()
        Dim Month1 As New Year With {.Months = "January"}
        Dim Month2 As New Year With {.Months = "Febuary"}
        Dim Month3 As New Year With {.Months = "March"}
        Dim Month4 As New Year With {.Months = "April"}
        Dim Month5 As New Year With {.Months = "May"}
        Dim Month6 As New Year With {.Months = "June"}
        Dim Month7 As New Year With {.Months = "July"}
        Dim Month8 As New Year With {.Months = "August"}
        Dim Month9 As New Year With {.Months = "September"}
        Dim Month10 As New Year With {.Months = "October"}
        Dim Month11 As New Year With {.Months = "November"}
        Dim Month12 As New Year With {.Months = "December"}

        Dim ArrList As New ArrayList()
        ArrList.Add(Month1)
        ArrList.Add(Month2)
        ArrList.Add(Month3)
        ArrList.Add(Month4)
        ArrList.Add(Month5)
        ArrList.Add(Month6)
        ArrList.Add(Month7)
        ArrList.Add(Month8)
        ArrList.Add(Month9)
        ArrList.Add(Month10)
        ArrList.Add(Month11)
        ArrList.Add(Month12)

        ' Use an explicit type for non-generic collections 
        Dim Q = From R As Year In ArrList
                        Select R Order By R.Months

        DataGridView1.DataSource = Q.ToList

    End Sub

    Private Sub Form1_Load(sender As Object, e As System.EventArgs) Handles Me.Load
        OrderByMonth()
    End Sub
End Class

Posted 6-Mar-12 19:37pm

It is what it is

Updated 10-Mar-12 9:22am

v3

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2 solutions

Solution 2

Something similar was asked Here[^]

And Luc Pattyn states here in his reply[^]

Databinding to the datagridview uses reflection to build the results, hence this sort of results. So Naerlings answer would solve your problem.

Posted 6-Mar-12 22:50pm

Simon_Whale

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Sander Rossel · Accepted Answer · 2012-03-06T20:55:00

Solution 1

You're actually binding to the String Object[^], which has a Property Length[^], but no Property which contains the String itself (thus the name of the month). It has the Default Property Chars[^], but this cannot be bound to.
I've had this problem when binding to Strings and Integers.
In your case you could create a DataTable[^] first, fill it with the names of the months (using a For Each Loop[^]) and then bind to that.
An alternative is to create a Class which stores your String as a value and bind to that, like so:

VB

Public Class MyValue(Of T)
   Public Property Value As T
End Class

Now you can put your String in there and bind to the MyValue Class.
Hope it helps :)

Posted 6-Mar-12 20:55pm

Sander Rossel

Updated 6-Mar-12 20:58pm

v2

Comments

Simon_Whale 7-Mar-12 4:50am

Nice answer +5

Sander Rossel 7-Mar-12 13:11pm

Thanks :)

It is what it is 10-Mar-12 15:19pm

Ok, so I took your advise and went with the "Class" option, I stole bits of code from here and there and cobbled together the solution and added it to the original question.

However; not sure if you would have done it the same??, and it seems a bit long and wordy could you suggest a way to reduce code?

Sander Rossel 10-Mar-12 19:07pm

How about:

Public Class Year
Public Sub New(Byval month As String)
Me.Month = month
End Sub
Public Property Month As String
End Class

Now in your Form you can do:
Dim list As New List(Of Year)
list.Add(New Year("January"))
list.Add(New Year("February"))
list.Add(New Year("March"))

...Etc.
This approach saves you half of the lines of code :)
I really suggest you use a List(Of T) instead of ArrayList too.

It is what it is 10-Mar-12 20:55pm

Sweet :-)