Passing Download complete Event with parameter to another class - vb.net

Question

I have an application whose main window upon click of a button gives users an option to load a list of files in the cloud.
Private Sub ImportCloudContent()
Dim cloudForm As Form_CloudImport
cloudForm = New Form_CloudImport()
cloudForm.Show()
cloudForm.populateDataGrid()
AddHandler cloudForm._DownloadComplete, New EventHandler(AddressOf OpenProject)
cloudForm.DownloadNotifier(FullPathOfContent)
End Sub
Ideally I should be able to get the value of the FullPathOfContent variable and pass it onto Open Project, but I am not sure how to go about it.
In the new Window users can click and download the file they want. Below is the section of code that handles the download in the Form_CloudImport class :
Private Async Sub Btn_download_Click(sender As Object, e As EventArgs) Handles Btn_download.Click
Dim fileNameRows As DataGridViewSelectedRowCollection = datagridview_cloudContent.SelectedRows
Dim fileName As String
Dim fileType As String = Cloud.CONTENT
Dim FullPathOfContent As String
For Each fileNameRow As DataGridViewRow In fileNameRows
fileName = fileNameRow.Cells(0).Value.ToString() & ".zip"
Try
FullPathOfContent = CloudToCCT(fileName, fileType)
Catch ex As Exception
CSMessageBox.ShowError("Content Import failed : ", ex)
End Try
Next
Me.Close()
DownloadNotifier(FullPathOfContent)
End Sub
Once the download is complete, the main window needs to call some of its methods. I am new to VB and have created a custom event to facilitate this(again in the Form_CloudImport class)
Public Event _DownloadComplete(e As String)
Public Sub DownloadNotifier(FullPathOfContent As String)
RaiseEvent _DownloadComplete(FullPathOfContent)
End Sub
According to what have read, once the download method is complete, it will fire the DownloadNotifier method, which will raise the _DownloadComplete event and the MainWindow should trigger the following events.
However, I receive the below errors in the MainWindow part of the code :
Value of type 'MainWindow.EventHandler' cannot be converted to 'Form_CloudImport._DownloadCompleteEventHandler'
and
'FullPathOfContent' is not declared. It may be inaccessible due to its protection level.
This question seems to be very long but any help would be appreciated. Thank you in advance!

Answer 1

First things first, you should create a type and event with proper names and signature and raise it properly.
Public Class CloudImportForm
Public Event DownloadComplete As EventHandler(Of DownloadCompleteEventArgs)
Protected Overridable Sub OnDownloadComplete(e As DownloadCompleteEventArgs)
RaiseEvent DownloadComplete(Me, e)
End Sub
'...
End Class
Public Class DownloadCompleteEventArgs
Inherits EventArgs
Public Sub New(contentPath As String)
Me.ContentPath = contentPath
End Sub
Public ReadOnly Property ContentPath As String
End Class
In that form, you would have code that performed a download and then raised that event.
'...
Dim contentPath = GetContentPath()
'Perform download here.
'Raise event.
OnDownloadComplete(New DownloadCompleteEventArgs(contentPath))
In your main form you would create and configure the download form, which includes handling the event, and then display it.
Dim cloudForm As New CloudImportForm
AddHandler cloudForm.DownloadComplete, AddressOf CloudImportForm_DownloadComplete
cloudForm.PopulateDataGrid()
cloudForm.Show()
The method you specify as the event handler should have the appropriate signature and it should retrieve the content path from the e parameter.
Private Sub CloudImportForm_DownloadComplete(sender As Object, e As DownloadCompleteEventArgs)
Dim contentPath = e.ContentPath
'Use contentPath here.
End Sub