(Visual Basic 6.0) Google Drive - Build a Local Cache of Metadata

This example demonstrates how to download the metadata for all files in a Google Drive account to create a local filesystem cache with the information. The cache can be used to fetch information without having to query Google Drive.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

Dim success As Long
success = 1

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

' This example uses a previously obtained access token having permission for the 
' Google Drive scope.

Dim gAuth As New ChilkatAuthGoogle
gAuth.AccessToken = "GOOGLE_DRIVE_ACCESS_TOKEN"

Dim rest As New ChilkatRest

' Connect using TLS.
Dim bAutoReconnect As Long
bAutoReconnect = 1
success = rest.Connect("www.googleapis.com",443,1,bAutoReconnect)

' Provide the authentication credentials (i.e. the access token)
success = rest.SetAuthGoogle(gAuth)

' -------------------------------------------------------------------
' Initialize our cache object.  Indicate the location of the root cache directory, and how many cache levels are to exist.
' For small caches (level 0) all cache files are in the root directory.
' For medium caches (level 1) cache files are located in 256 sub-directories from the root.
' For large caches (level 2) cache files are located in 256x256 sub-directories two levels down from the root.
Dim gdCache As New ChilkatCache
gdCache.Level = 0
' Use a root directory that makes sense on your operating system..
gdCache.AddRoot "C:/ckCache/googleDrive"

' If we are re-building the cache, we can first delete the entire contents of the cache.
Dim numCacheFilesDeleted As Long
numCacheFilesDeleted = gdCache.DeleteAll()

' Create a date/time object with an time 7 days from the current date/time.
Dim dtExpire As New CkDateTime
success = dtExpire.SetFromCurrentSystemTime()
success = dtExpire.AddDays(7)

' Indicate that we want ALL possible fields.
' If no fields are indicated, then only the basic fields are returned.
Dim allFields As String
allFields = "appProperties,capabilities,contentHints,createdTime,description,explicitlyTrashed,fileExtension,folderColorRgb,fullFileExtension,headRevisionId,iconLink,id,imageMediaMetadata,isAppAuthorized,kind,lastModifyingUser,md5Checksum,mimeType,modifiedByMeTime,modifiedTime,name,originalFilename,ownedByMe,owners,parents,permissions,properties,quotaBytesUsed,shared,sharedWithMeTime,sharingUser,size,spaces,starred,thumbnailLink,trashed,version,videoMediaMetadata,viewedByMe,viewedByMeTime,viewersCanCopyContent,webContentLink,webViewLink,writersCanShare"

' We're going to keep a master list of fileId's as we iterate over all the files in this Google Drive account.
' This master list will also be saved to the cache under the key "AllGoogleDriveFileIds".
Dim jsonMaster As New ChilkatJsonObject
Dim jsonMasterArr As ChilkatJsonArray
Set jsonMasterArr = jsonMaster.AppendArray("fileIds")
' Also keep a list of file paths.
Dim jsonMasterPaths As ChilkatJsonArray
Set jsonMasterPaths = jsonMaster.AppendArray("filePaths")

' The default page size is 100, with a max of 1000.
success = rest.AddQueryParam("pageSize","200")

Dim json As New ChilkatJsonObject
Dim jsonFileMetadata As ChilkatJsonObject
Dim i As Long
Dim numFiles As Long

' Send the request for the 1st page.
Dim jsonResponse As String
jsonResponse = rest.FullRequestNoBody("GET","/drive/v3/files")

Dim pageNumber As Long
pageNumber = 1
Dim pageToken As String
Dim bContinueLoop As Long
bContinueLoop = rest.LastMethodSuccess And (rest.ResponseStatusCode = 200)

Do While bContinueLoop = 1

    Debug.Print "---- Page " & pageNumber & " ----"
    success = json.Load(jsonResponse)

    numFiles = json.SizeOfArray("files")
    i = 0
    Do While i < numFiles
        ' Add this file ID to the master list.
        json.I = i
        success = jsonMasterArr.AddStringAt(-1,json.StringOf("files[i].id"))

        i = i + 1
    Loop

    ' Get the next page of files.
    ' If the "nextPageToken" is present in the JSON response, then use it in the "pageToken" parameter
    ' for the next request.   If no "nextPageToken" was present, then this was the last page of files.
    pageToken = json.StringOf("nextPageToken")
    bContinueLoop = 0
    Dim bHasMorePages As Long
    bHasMorePages = json.LastMethodSuccess
    If (bHasMorePages = 1) Then
        success = rest.ClearAllQueryParams()
        success = rest.AddQueryParam("pageSize","200")
        success = rest.AddQueryParam("pageToken",pageToken)
        jsonResponse = rest.FullRequestNoBody("GET","/drive/v3/files")
        bContinueLoop = rest.LastMethodSuccess And (rest.ResponseStatusCode = 200)
        pageNumber = pageNumber + 1
    End If

Loop

' Check to see if the above loop exited with errors...
If (rest.LastMethodSuccess <> 1) Then
    Debug.Print rest.LastErrorText
    Exit Sub
End If

' Check to see if the above loop exited with errors...
' A successful response will have a status code equal to 200.
If (rest.ResponseStatusCode <> 200) Then
    Debug.Print "response status code = " & rest.ResponseStatusCode
    Debug.Print "response status text = " & rest.ResponseStatusText
    Debug.Print "response header: " & rest.ResponseHeader
    Debug.Print "response JSON: " & jsonResponse
    Exit Sub
End If

' Iterate over the file IDs and download the metadata for each, saving each to the cache...
' Also, keep in-memory hash entries of the name and parent[0] so we can quickly 
' build the path-->fileId cache entries. (Given that the Google Drive REST API uses
' fileIds, this gives us an easy way to lookup a fileId based on a filePath.)
Dim hashTable As New ChilkatHashtable
' Set the capacity of the hash table to something reasonable for the number of files
' to be hashed.
success = hashTable.ClearWithNewCapacity(521)

Dim sbPathForFileId As New ChilkatStringBuilder

' Used for storing the file name and parents[0] in the hashTable.
Dim saFileInfo As New CkStringArray
saFileInfo.Unique = 0

Dim fileId As String
numFiles = jsonMaster.SizeOfArray("fileIds")
i = 0
Do While i < numFiles
    jsonMaster.I = i
    fileId = jsonMaster.StringOf("fileIds[i]")
    success = sbPathForFileId.SetString("/drive/v3/files/")
    success = sbPathForFileId.Append(fileId)

    success = rest.ClearAllQueryParams()
    success = rest.AddQueryParam("fields",allFields)
    jsonResponse = rest.FullRequestNoBody("GET",sbPathForFileId.GetAsString())
    If ((rest.LastMethodSuccess <> 1) Or (rest.ResponseStatusCode <> 200)) Then
        ' Force an exit of this loop..
        numFiles = 0
    End If

    ' Save this file's metadata to the local cache.
    ' The lookup key is the fileId.
    success = gdCache.SaveTextDt(fileId,dtExpire,"",jsonResponse)

    ' Get this file's name and parent[0], and put this information
    ' in our in-memory hashtable to be used below..
    success = json.Load(jsonResponse)

    saFileInfo.Clear 
    success = saFileInfo.Append(json.StringOf("name"))
    success = saFileInfo.Append(json.StringOf("parents[0]"))
    success = hashTable.AddStr(fileId,saFileInfo.Serialize())

    Debug.Print json.StringOf("name") & ", " & json.StringOf("parents[0]")

    i = i + 1
Loop

' Check to see if the above loop exited with errors...
If (rest.LastMethodSuccess <> 1) Then
    Debug.Print rest.LastErrorText
    Exit Sub
End If

' Check to see if the above loop exited with errors...
' A successful response will have a status code equal to 200.
If (rest.ResponseStatusCode <> 200) Then
    Debug.Print "response status code = " & rest.ResponseStatusCode
    Debug.Print "response status text = " & rest.ResponseStatusText
    Debug.Print "response header: " & rest.ResponseHeader
    Debug.Print "response JSON: " & jsonResponse
    Exit Sub
End If

' Now that all the fileId's are in the cache, let's build the directory path
' for each fileID.  

' (Technically, a fileId can have multiple parents, which means it can be in multiple directories
' at once.  This is only going to build directory paths following the 0'th parent ID in the parents list.)

' The directory path for files in "My Drive" will be just the filename.
' For files in sub-directories, the path will be relative, such as "subdir1/subdir2/something.pdf"
' 

Debug.Print "---- building paths ----"

Dim sbPath As New ChilkatStringBuilder
numFiles = jsonMaster.SizeOfArray("fileIds")
i = 0
Do While i < numFiles
    jsonMaster.I = i

    sbPath.Clear 

    fileId = jsonMaster.StringOf("fileIds[i]")
    Dim bFinished As Long
    bFinished = 0
    Do While (bFinished = 0)
        saFileInfo.Clear 
        success = saFileInfo.AppendSerialized(hashTable.LookupStr(fileId))
        ' Append this file or directory name.
        success = sbPath.Prepend(saFileInfo.GetString(0))
        ' Get the parent fileId
        fileId = saFileInfo.GetString(1)
        ' If this fileId is not in the hashtable, then it's the fileId for "My Drive", and we are finished.
        If (hashTable.Contains(fileId) = 0) Then
            bFinished = 1
        Else
            success = sbPath.Prepend("/")
        End If

    Loop

    Debug.Print i & ": " & sbPath.GetAsString()

    ' Store the filePath --> fileId mapping in our local cache.
    fileId = jsonMaster.StringOf("fileIds[i]")
    success = gdCache.SaveTextDt(sbPath.GetAsString(),dtExpire,"",fileId)

    success = jsonMasterPaths.AddStringAt(-1,sbPath.GetAsString())

    i = i + 1
Loop

' Save the master list of file IDs and file paths to the local cache.
jsonMaster.EmitCompact = 0
Dim strJsonMaster As String
strJsonMaster = jsonMaster.Emit()
success = gdCache.SaveTextNoExpire("AllGoogleDriveFileIds","",strJsonMaster)
Debug.Print "JSON Master Record:"
Debug.Print strJsonMaster

' The JSON Master Cache Record looks something like this:
' An application can load the JSON master record and iterate over all the files
' in Google Drive by file ID, or by path.  
' {
'   "fileIds": [
'     "0B53Q6OSTWYolQlExSlBQT1phZXM",
'     "0B53Q6OSTWYolVHRPVkxtYWFtZkk",
'     "0B53Q6OSTWYolRGZEV3ZGUTZfNFk",
'     "0B53Q6OSTWYolS2FXSjliMXQxSU0",
'     "0B53Q6OSTWYolZUhxckMzb0dRMzg",
'     "0B53Q6OSTWYolbUF6WS1Gei1oalk",
'     "0B53Q6OSTWYola296ODZUSm5GYU0",
'     "0B53Q6OSTWYolbTE3c3J5RHBUcHM",
'     "0B53Q6OSTWYolTmhybWJSUGd5Q2c",
'     "0B53Q6OSTWYolY2tPU1BnYW02T2c",
'     "0B53Q6OSTWYolTTBBR2NvUE81Zzg",
'   ],
'   "filePaths": [
'     "testFolder/abc/123/pigs.json",
'     "testFolder/starfish20.jpg",
'     "testFolder/penguins2.jpg",
'     "testFolder/starfish.jpg",
'     "testFolder/abc/123/starfish.jpg",
'     "testFolder/abc/123/penguins.jpg",
'     "testFolder/abc/123",
'     "testFolder/abc",
'     "testFolder/testHello.txt",
'     "testFolder",
'     "helloWorld.txt",
'   ]
' }

Debug.Print "Entire cache rebuilt..."