Finishing up the ImportBooks code

Let's have a look at the rest of the code in the ImportBooks form. The form load just populates the storage spaces list, if any existing storage spaces have been previously saved:

private void ImportBooks_Load(object sender, EventArgs e) 
{ 
    PopulateStorageSpacesList(); 
                         
    if (dlVirtualStorageSpaces.Items.Count == 0) 
    { 
        dlVirtualStorageSpaces.Items.Add("<create new storage 
        space>"); 
    } 
 
    lblEbookCount.Text = ""; 
} 

We now need to add the logic for changing the selected storage space. The SelectedIndexChanged() event of the dlVirtualStorageSpaces control is modified as follows:

private void dlVirtualStorageSpaces_SelectedIndexChanged(object sender, EventArgs e) 
{ 
    int selectedValue = 
    dlVirtualStorageSpaces.SelectedValue.ToString().ToInt(); 
 
    if (selectedValue == (int)StorageSpaceSelection.New) // -9999 
    { 
        txtNewStorageSpaceName.Visible = true; 
        lblStorageSpaceDescription.Visible = true; 
        txtStorageSpaceDescription.ReadOnly = false; 
        btnSaveNewStorageSpace.Visible = true; 
        btnCancelNewStorageSpaceSave.Visible = true; 
        dlVirtualStorageSpaces.Enabled = false; 
        btnAddNewStorageSpace.Enabled = false; 
        lblEbookCount.Text = ""; 
    } 
    else if (selectedValue != 
    (int)StorageSpaceSelection.NoSelection) 
    { 
        // Find the contents of the selected storage space 
        int contentCount = (from c in spaces 
                            where c.ID == selectedValue 
                            select c).Count(); 
        if (contentCount > 0) 
        { 
            StorageSpace selectedSpace = (from c in spaces 
                                          where c.ID == 
                                          selectedValue 
                                          select c).First(); 
 
            txtStorageSpaceDescription.Text = 
            selectedSpace.Description; 
 
            List<Document> eBooks = (selectedSpace.BookList == 
            null) 
             ? new List<Document> { } : selectedSpace.BookList; 
            lblEbookCount.Text = $"Storage Space contains 
             {eBooks.Count()} {(eBooks.Count() == 1 ? "eBook" :
             "eBooks")}"; 
        } 
    } 
    else 
    { 
        lblEbookCount.Text = ""; 
    } 
} 

I will not go into any detailed explanation of the code here as it is relatively obvious what it is doing.