So I work from time to time in Winforms on a legacy app and am not familiar with best practices at all times with binding objects. Basically I have a three part set where I have two people, they may have only one product, but that product could cause the possibility to have different sets of SKUs. Is there a way to trigger an event and population of a combobox from the values of a first combobox? I have been looking around and I am either finding basic data of just how to bind a combobox(I can do that fine) or do something with how you bind it. Not binding after a dependent parent change is triggered and changing the dataset. Example below:
POCOS:
Public Class Person
Public Property PersonID As Integer
Public Property FirstName As String
Public Property LastName As String
Public Property ProductId As Integer
Public Property SkuId As Integer
End Class
Public Class Product
Public Property ProductId As Integer
Public Property Description As String
End Class
Public Class Sku
Public Property SKUId As Integer
Public Property ProductId As Integer
Public Property Description As String
End Class
Main code example (basic UI really only has a Datset labeled 'ds' that matches nearly identically the Person and Product POCOS with datatables. A datagridview 'dgv' whose columns are bound to data in Person EXCEPT for a column called SKU that has no binding as I want to bind it after the fact and that is where I am failing miserably at.
Update 9-13-2016
I can get the below code to work EXCEPT in certain large scale solutions(the whole reason I did this). It basically will NOT execute the line that casts the cell() to a datagridviewcomboboxcell and ignores it and jumps over the line. No reason why, it just jumps over it. I am wondering if in larger classes the datagrid views can become corrupt or something.
Main Code:
Private _people As List(Of Person) = New List(Of Person)
Private _products As List(Of Product) = New List(Of Product)
Private _SKUs As List(Of Sku) = New List(Of Sku)
Private _initialLoadDone = False
Private _currentRow As Integer? = Nothing
Private Sub DynamicComboBoxDoubleFill_Load(sender As Object, e As EventArgs) Handles MyBase.Load
_products = New List(Of Product)({
New Product With {.ProductId = 1, .Description = "Offline"},
New Product With {.ProductId = 2, .Description = "Online"}
})
Dim s = ""
For Each o In _products
Dim row As DataRow = ds.Tables("tProducts").NewRow
row("ProductId") = o.ProductId
row("Description") = o.Description
ds.Tables("tProducts").Rows.Add(row)
Next
_SKUs = New List(Of Sku)({
New Sku With {.SKUId = 1, .ProductId = 1, .Description = "Mail"},
New Sku With {.SKUId = 2, .ProductId = 1, .Description = "Magazine"},
New Sku With {.SKUId = 3, .ProductId = 2, .Description = "Email"},
New Sku With {.SKUId = 4, .ProductId = 2, .Description = "APIRequest"}
})
Dim items = _SKUs
_people = New List(Of Person)({
New Person With {.PersonID = 1, .FirstName = "Emily", .LastName = "X", .ProductId = 1, .SkuId = 1},
New Person With {.PersonID = 2, .FirstName = "Brett", .LastName = "X", .ProductId = 2, .SkuId = 3}
})
For Each p In _people
Dim row As DataRow = ds.Tables("tPeople").NewRow
row("PersonId") = p.PersonId
row("FirstName") = p.FirstName
row("LastName") = p.LastName
row("ProductId") = p.ProductId
row("SkuId") = p.SkuId
ds.Tables("tPeople").Rows.Add(row)
Next
For Each row As DataGridViewRow In dgv.Rows
ArrangeValuesForSKUComboBox(row)
Next
_initialLoadDone = True
End Sub
Private Sub ArrangeValuesForSKUComboBox(row As DataGridViewRow)
Dim productId = CInt(row.Cells("ProductId")?.Value)
Dim skus = _SKUs.Where(Function(x) x.ProductId = productId).ToList().Select(Function(x) New With {Key .SkuId = x.SKUId, .SkuDesc = x.Description}).ToList()
Dim cell = row.Cells("SKU")
'Yeah I don't always work. In this example I do, in others I won't.
'For this reason I just want more ideas. I don't care if you completely blow up how the binding is done and do something else entirely.
Dim combobox = CType(cell, DataGridViewComboBoxCell)
combobox.DataSource = skus
combobox.ValueMember = "SKUId"
combobox.DisplayMember = "SkuDesc"
combobox.Value = skus.FirstOrDefault()?.SkuId
End Sub
Private Sub dgv_CellValueChanged(sender As Object, e As DataGridViewCellEventArgs) Handles dgv.CellValueChanged
If _initialLoadDone Then
Dim headerText As String = TryCast(sender, DataGridView).Columns(e.ColumnIndex).HeaderText
If headerText = "PRODUCT" Then
ArrangeValuesForSKUComboBox(dgv?.CurrentRow)
End If
End If
End Sub
