(VB.NET UWP/WinRT) SharePoint -- Download Newer Files

Demonstrates how to download all files from a SharePoint folder that are newer than the local files.

Chilkat Universal Windows Platform (UWP) / WinRT Downloads Chilkat for the Universal Windows Platform (UWP)

'  This requires the Chilkat API to have been previously unlocked.
'  See Global Unlock Sample for sample code.

'  -------------------------------------------------------------------------
'  The following comments apply to SharePoint Windows classic authentication.
'  -------------------------------------------------------------------------
'  For example, imagine our SharePoint endpoint is https://xyzoffice.mycompany.com/
'  The SHAREPOINT_NTLM_DOMAIN would be "mycompany.com"
'  The SHAREPOINT_HTTPS_DOMAIN would be "xyzoffice.mycompany.com"
'  Also, the SHAREPOINT_USERNAME would be just the name, not a full email address.
'  for example, "chilkat" instead of "chilkat@mycompany.com"

Dim http As New Chilkat.Http

'  If SharePoint Windows classic authentication is used, then set the
'  Login, Password, LoginDomain, and NtlmAuth properties.
http.Login = "SHAREPOINT_USERNAME"
http.Password = "SHAREPOINT_PASSWORD"
http.LoginDomain = "SHAREPOINT_NTLM_DOMAIN"
http.NtlmAuth = True

'  -------------------------------------------------------------------------
'  The more common case is to use SharePoint Online authentication (via the SPOIDCRL cookie).
'  If so, do not set Login, Password, LoginDomain, and NtlmAuth, and instead
'  establish the cookie as shown at SharePoint Online Authentication
'  -------------------------------------------------------------------------


'  First we'll download a list of all the files in the /Documents folder.
'  This provides the names and last-modified date/times of the files located
'  on the SharePoint server.
http.Accept = "application/json;odata=verbose"

Dim sbJson As New Chilkat.StringBuilder
Dim success As Boolean = Await http.QuickGetSbAsync("https://SHAREPOINT_HTTPS_DOMAIN/_api/web/GetFolderByServerRelativeUrl('/Documents')/Files",sbJson)
If (success <> True) Then
    Debug.WriteLine(http.LastErrorText)
    Exit Sub
End If



'  Before proceeding, make sure the local directory where we'll be downloading files exists.
Dim fac As New Chilkat.FileAccess
fac.DirEnsureExists("qa_output/sharepoint/Documents")

'  OK.. load the JSON and iterate over each file
Dim json As New Chilkat.JsonObject
json.LoadSb(sbJson)

Dim numFiles As Integer = json.SizeOfArray("d.results")
Debug.WriteLine("Number of Files in the SharePoint /Documents folder = " & numFiles)

Dim lastModRemote As New Chilkat.CkDateTime
Dim lastModLocal As Chilkat.CkDateTime

Dim localPath As New Chilkat.StringBuilder
Dim fileUrl As New Chilkat.StringBuilder

Dim i As Integer = 0
While i < numFiles
    json.I = i

    Dim filename As String = json.StringOf("d.results[i].Name")
    Dim sLastModified As String = json.StringOf("d.results[i].TimeLastModified")

    Debug.WriteLine((i + 1) & ": " & filename & " (" & sLastModified & ")")

    lastModRemote.SetFromTimestamp(sLastModified)

    Dim bDownload As Boolean = False
    '  Check to see if the local file exists.  If not, then download.
    localPath.SetString("qa_output/sharepoint/Documents/")
    localPath.Append(filename)
    If (fac.FileExists(localPath.GetAsString()) <> True) Then
        Debug.WriteLine("This file does not exist locally.")
        bDownload = True
    Else
        '  Get the local file's date time and compare with the remote file date/time.
        lastModLocal = fac.GetLastModified(localPath.GetAsString())
        If (fac.LastMethodSuccess = True) Then
            '  Get the difference in seconds between the local and remote last-modified times.
            '  if the return value is negative, then the caller's time is
            '  older than the argument.  (in this case, a negative return value means
            '  the local file is older than the remote file.

            '  Note: The DiffSeconds method was found to be missing in the Chilkat .NET build
            '  (and possibly in other builds). It will be present in the v9.5.0.67 release and later.
            Dim numSeconds As Integer = lastModLocal.DiffSeconds(lastModRemote)
            If (numSeconds < 0) Then
                Debug.WriteLine("The local file is older than the remote file.")
                bDownload = True
            End If


        Else
            Debug.WriteLine("Unable to get the local file's last-modified date/time.")
            Debug.WriteLine(fac.LastErrorText)
        End If

    End If


    If (bDownload = True) Then
        fileUrl.SetString("https://SHAREPOINT_HTTPS_DOMAIN/_api/web/GetFolderByServerRelativeUrl('/Documents')/Files('")
        fileUrl.Append(filename)
        fileUrl.Append("')/$value")

        Debug.WriteLine("Downloading " & filename)

        success = Await http.DownloadAsync(fileUrl.GetAsString(),localPath.GetAsString())
        If (success <> True) Then
            Debug.WriteLine(http.LastErrorText)
            Exit Sub
        End If


        '  Set the local file's last-modified date/time to that of the server's.
        fac.SetLastModified(localPath.GetAsString(),lastModRemote)

    End If


    i = i + 1
End While

Debug.WriteLine("All finished.")