VB.Net Dictionary inside of a dictionary adding / removing data - vb.net

Question

I'm creating an application where I have different libraries, books and non-book media stored in dictionaries and displayed in listboxes. The user can add and remove additional dictionaries for any of these 3 elements. My issue lies in bringing up the new form to create a link between a library and it's media.
I have a listbox for "Books at Current library" and "Non-Book Media at Current Library" Which will display the media that is linked to the specific library that is highlighted in the listbox. And the user can freely add and remove different media to the library.
frmManager: https://prnt.sc/mnd8qf
frmAssociationScreen: https://prnt.sc/mnd8sh
I'm trying to create a dictionary within a dictionary that I can manipulate the data with for adding the different media to the individual libraries. But I'm unsure where to go from here, I'd like to start by hard coding a few links to Zahnow Library and add a few books as well as one non-book media.
Public Class frmManager
' Global data structures
Public Libraries As New Dictionary(Of String, String)
Public Books As New Dictionary(Of String, String)
Public nonBookMedia As New Dictionary(Of String, String)
Public EquippedLibrary As New Dictionary(Of String, LibraryWithMedia)
Structure LibraryWithMedia
Dim strLibraryName As String
Dim dicBooks As Dictionary(Of String, String)
Dim nonBookMedia As Dictionary(Of String, String)
End Structure
Private Sub frmManager_Load(sender As Object, e As EventArgs) Handles Me.Load
Libraries.Add("SVSU", "Zahnow Library")
Libraries.Add("BR", "Fleschner Memorial Library")
Libraries.Add("SDJ", "Scott D. James Technical Repository")
Books.Add("104", "Data Structures for Fun and Profit")
Books.Add("103", "Doing More With Less - Naval Lint Art")
Books.Add("102", "Interpretive Klingon Poetry")
Books.Add("105", "Programming with the Bidgoli")
Books.Add("101", "Zen and the Art of Appliance Wiring")
nonBookMedia.Add("201", "CD - IEEE Computer: the Hits")
nonBookMedia.Add("203", "DVD - Databases and You: the Video Experience")
nonBookMedia.Add("202", "DVD - The Pirates of Silicon Valley")
populatelstLibrary()
populatelstBooks()
populatelstBookMedia()
End Sub
Sub populatelstLibrary()
lstLibraries.Items.Clear()
For Each library In Libraries
lstLibraries.Items.Add(library.Value & " --- " & library.Key)
Next
End Sub
How I manipulated the data to delete library dictionary
Private Sub btnDeleteLibrary_Click(sender As Object, e As EventArgs) Handles btnDeleteLibrary.Click
Dim key As String = ""
Dim tmpLibraries As New Dictionary(Of String, String)
' If an index is selected in listbox then continue
' If nothing selected, the button does nothing
If lstLibraries.SelectedIndex > -1 Then
If MsgBox("Are you sure you want to delete this library?", MsgBoxStyle.YesNoCancel, "Delete confirmation") = MsgBoxResult.Yes Then
For Each library In Libraries
If lstLibraries.SelectedItem.Equals(library.Value & " --- " & library.Key) Then
' DoNothing
' the selected item is not added to temp library
Else
' Add all other values to temp library
tmpLibraries.Add(library.Key, library.Value)
End If
Next
lstLibraries.Items.Clear() ' Clear the list box
Libraries = tmpLibraries ' Set dictionary Libraries equal to temp libararies
tmpLibraries = Nothing ' Set temp library back to nothing
populatelstLibrary() ' Repopulate the list box
End If
End If
End Sub
frmAssociationScreen.vb
Public Class frmAssociationScreen
Private Sub frmAssociationScreen_Load(sender As Object, e As EventArgs) Handles Me.Load
lstAllLibraries.Items.Clear()
For Each library In frmManager.Libraries
lstAllLibraries.Items.Add(library.Value & " --- " & library.Key)
Next
For Each book In frmManager.Books
lstAllBooks.Items.Add(book.Value & " --- " & book.Key)
Next
For Each nonBook In frmManager.nonBookMedia
lstAllMedia.Items.Add(nonBook.Value & " --- " & nonBook.Key)
Next
End Sub
Private Sub btnManagerScreen_Click(sender As Object, e As EventArgs) Handles btnManagerScreen.Click
Me.Close() ' Close current form
frmManager.Visible = True ' Make manager form visible
End Sub
Private Sub btnAddBook_Click(sender As Object, e As EventArgs) Handles btnAddBook.Click
End Sub
Private Sub btnRemoveBook_Click(sender As Object, e As EventArgs) Handles btnRemoveBook.Click
End Sub
Private Sub lstAllLibraries_SelectedIndexChanged(sender As Object, e As EventArgs) Handles lstAllLibraries.SelectedIndexChanged
End Sub
End Class

Answer 1

Some slight changes in your code as below:
In your structure LibraryWithMedia
We added SUB NEW
' Structure of single library
Structure LibraryWithMedia
'
Dim strLibraryName As String
Dim dicBooks As Dictionary(Of String, String)
Dim nonBookMedia As Dictionary(Of String, String)
'
'new library constructor
Sub New(ByVal LibName As String)
strLibraryName = LibName
dicBooks = New Dictionary(Of String, String)
nonBookMedia = New Dictionary(Of String, String)
End Sub
'
End Structure
In your EquippedLibrary declaration.
The declaration changed from (string, string) to simply LibraryWithMedia
Public EquippedLibrary As List(Of LibraryWithMedia)
At the end/bottom of your Form_Load event
' construct equipped library and define the library names
EquippedLibrary = New List(Of LibraryWithMedia)
' initialise each library with empty books/media dictionaries
populateEquippedLibNames
The PopulateEquippedLibNames Subroutines (this is a new subroutine)
Sub populateEquippedLibNames()
'
Dim Counta As Integer
Dim tmpSingleLib As LibraryWithMedia
'
For Counta = 0 To Libraries.Count - 1
tmpSingleLib = New LibraryWithMedia(Libraries.Values(Counta))
EquippedLibrary.Add(tmpSingleLib)
tmpSingleLib = Nothing
Next
'
End Sub
And then for adding/removing each book to the SELECTED library in the TOP listbox
Private Sub btnAddBook_Click(sender As Object, e As EventArgs) Handles btnAddBook.Click
'
EquippedLibrary(lstLibraries.SelectedIndex).dicBooks.Add(Books.Keys(lstBooks.SelectedIndex), Books.Values(lstBooks.SelectedIndex))
lstSelectedBooks.Items.Add(lstBooks.SelectedItem)
'
End Sub
Private Sub btnRemoveBook_Click(sender As Object, e As EventArgs) Handles btnRemoveBook.Click
'
EquippedLibrary(lstLibraries.SelectedIndex).dicBooks.Remove(Books.Keys(lstBooks.SelectedIndex))
'
End Sub
Note that to add a book/media to a library,
A library MUST BE selected in the TOP listbox
The Book or Media being added must also be selected
No error checking is performed, so you will need to add it (such as a listbox has a selection or not) etc
Update
I have added the libraries on change code for you below
Private Sub lstLibraries_SelectedIndexChanged(sender As Object, e As EventArgs) Handles lstLibraries.SelectedIndexChanged
'
Dim Counta As Integer
'
lstSelectedBooks.Items.Clear()
lstSelectedMedia.Items.Clear()
If EquippedLibrary(lstLibraries.SelectedIndex).dicBooks.Count > 0 Then
For Counta = 0 To EquippedLibrary(lstLibraries.SelectedIndex).dicBooks.Count - 1
lstSelectedBooks.Items.Add(EquippedLibrary(lstLibraries.SelectedIndex).dicBooks.Keys(Counta) & " --- " & EquippedLibrary(lstLibraries.SelectedIndex).dicBooks.Values(Counta))
Next
End If
Counta = Nothing
'
End Sub