How to bind the selected member of a ComboBox? - vb.net

Question

I have a ComboBox that is populated with objects of type ProfileName
Private Class ProfileName
Public Property Name As String
Public Property File As String
Public Property ProductVersion As String
End Class
These items are created added to the combo box after a deserialising a bunch of files and copying some of the values from the resulting objects:
pcb.DisplayMember = "Name"
For Each F As FileInfo In ProfileFiles
Dim Reader As StreamReader = F.OpenText()
Dim Serialize As Serializer = New Serializer()
Dim SerializedData As String = Reader.ReadToEnd()
Dim P As Profile = Serialize.DesearializeObject(Of Profile)(SerializedData)
If P.Type = Profile.ProfileType.Product Then
Dim PN As ProfileName = New ProfileName()
PN.File = F.Name
PN.ProductVersion = P.ProductVersion
PN.Name = P.ProductName & " - " & P.ProductVersion
pcb.Items.Add(PN)
End If
Reader.Close()
Next
Then if a user opens one of these files, the file will be again deserialised resulting in a Profile object with a 'ProductName' property that should match one of the items already on the ComboBox items list, so I'd like for the ComboBox to show that as the selected item.
i.e.
-On form load the ComboBox is populated with all possible product names.
-When a profile file is opened the product that the profile uses is automatically selected in the ComboBox.
I've been playing with
ProductComboBox.DataBindings.Add("SelectedValue", CurrentProfile, "ProductName")
and permutations thereof, but can't seem to get it right.

Answer 1

You cant mix and match - put objects into the items collection and use the data binding methods/elements. Databinding basics:
Public Class Profile
Public Property Name As String
Public Property File As String
Public Property ProductVersion As String
Public Overrides Function ToString() As String
Return String.Format("{0} ({1})", Name, ProductVersion)
End Function
End Class
The ToString() controls what will be displayed when you cant specify the property to display. Note, these should be properties becaus mere Fields will be treated differently.
Then a container for them. This will be the DataSource for the cbo.
Private Profiles As List(Of Profile)
...
' create instance of list and populate from where ever:
Profiles = New List(Of Profile)
Profiles.Add(New Profile With {.Name = "Default", .File = "foo",
.ProductVersion = "1.0"})
Profiles.Add(New Profile With {.Name = "Ziggy", .File = "bat",
.ProductVersion = "1.9.8"})
Profiles.Add(New Profile With {.Name = "Zoey", .File = "bar",
.ProductVersion = "1.4.1"})
Rather than putting the Profile objects into the Items collection, bind the control to the List:
cboP.DataSource = Profiles
cboP.DisplayMember = "Name"
If you omit the property to display, ToString() will be shown (or WindowsApp1.Profile if you did not override it). Note: When using a DataSource you no longer add or delete from the control's Items collection - it will yell at you. Instead manage the underlying source, your List(Of Profile) in this case.
To change the selection, for example to the one for "Ziggy":
Dim n As Int32 = Profiles.FindIndex(Function(f) f.Name = "Ziggy")
If n > -1 Then
cboP.SelectedIndex = n
End If
You can also set SelectedItem after you find the Profile instead, but I tend to use index. Even though the list is a new actor, serializing the entire thing is easy:
' serializing the List acts on all the profiles in it
Dim json = JsonConvert.SerializeObject(Profiles)
File.WriteAllText("C:\Temp\Profiles.json", json)
Read it back:
json = File.ReadAllText("C:\Temp\Profiles.json")
Dim newPs = JsonConvert.DeserializeObject(Of List(Of Profile))(json)
Its a bit simpler than looping thru a set of files. List(of T) has a full set of methods and extensions to remove, sort, find etc so you should gain functionality over the items collection or array.
Alternatively, you could keep the one file per structure, but add the deserialized Profile objects to a List(of Profile) rather than the Items collection.