Xojo Plugin

Google Drive - Build a Local Cache of Metadata

See more Google Drive Examples

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. Xojo Plugin

Dim success As Boolean
success = False

success = True

// 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 Chilkat.AuthGoogle
gAuth.AccessToken = "GOOGLE_DRIVE_ACCESS_TOKEN"

Dim rest As New Chilkat.Rest

// Connect using TLS.
Dim bAutoReconnect As Boolean
bAutoReconnect = True
success = rest.Connect("www.googleapis.com",443,True,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 Chilkat.Cache
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 Int32
numCacheFilesDeleted = gdCache.DeleteAll()

// Create a date/time object with an time 7 days from the current date/time.
Dim dtExpire As New Chilkat.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 Chilkat.JsonObject

Dim jsonMasterArr As New Chilkat.JsonArray
success = jsonMaster.AppendArray2("fileIds",jsonMasterArr)

// Also keep a list of file paths.
Dim jsonMasterPaths As New Chilkat.JsonArray
success = jsonMaster.AppendArray2("filePaths",jsonMasterPaths)

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

Dim json As New Chilkat.JsonObject
Dim jsonFileMetadata As Chilkat.JsonObject
Dim i As Int32
Dim numFiles As Int32

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

Dim pageNumber As Int32
pageNumber = 1
Dim pageToken As String
Dim bContinueLoop As Boolean
bContinueLoop = rest.LastMethodSuccess And (rest.ResponseStatusCode = 200)

While bContinueLoop = True

    System.DebugLog("---- Page " + Str(pageNumber) + " ----")
    success = json.Load(jsonResponse)

    numFiles = json.SizeOfArray("files")
    i = 0
    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
    Wend

    // 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 = False
    Dim bHasMorePages As Boolean
    bHasMorePages = json.LastMethodSuccess
    If (bHasMorePages = True) 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

Wend

// Check to see if the above loop exited with errors...
If (rest.LastMethodSuccess = False) Then
    System.DebugLog(rest.LastErrorText)
    Return
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
    System.DebugLog("response status code = " + Str(rest.ResponseStatusCode))
    System.DebugLog("response status text = " + rest.ResponseStatusText)
    System.DebugLog("response header: " + rest.ResponseHeader)
    System.DebugLog("response JSON: " + jsonResponse)
    Return
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 Chilkat.Hashtable
// 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 Chilkat.StringBuilder

// Used for storing the file name and parents[0] in the hashTable.
Dim saFileInfo As New Chilkat.StringArray
saFileInfo.Unique = False

Dim fileId As String
numFiles = jsonMaster.SizeOfArray("fileIds")
i = 0
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 <> True) 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())

    System.DebugLog(json.StringOf("name") + ", " + json.StringOf("parents[0]"))

    i = i + 1
Wend

// Check to see if the above loop exited with errors...
If (rest.LastMethodSuccess = False) Then
    System.DebugLog(rest.LastErrorText)
    Return
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
    System.DebugLog("response status code = " + Str(rest.ResponseStatusCode))
    System.DebugLog("response status text = " + rest.ResponseStatusText)
    System.DebugLog("response header: " + rest.ResponseHeader)
    System.DebugLog("response JSON: " + jsonResponse)
    Return
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"
// 

System.DebugLog("---- building paths ----")

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

    sbPath.Clear 

    fileId = jsonMaster.StringOf("fileIds[i]")
    Dim bFinished As Boolean
    bFinished = False
    While (bFinished = False)
        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) = False) Then
            bFinished = True
        Else
            success = sbPath.Prepend("/")
        End If

    Wend

    System.DebugLog(Str(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
Wend

// Save the master list of file IDs and file paths to the local cache.
jsonMaster.EmitCompact = False
Dim strJsonMaster As String
strJsonMaster = jsonMaster.Emit()
success = gdCache.SaveTextNoExpire("AllGoogleDriveFileIds","",strJsonMaster)
System.DebugLog("JSON Master Record:")
System.DebugLog(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",
//   ]
// }

System.DebugLog("Entire cache rebuilt...")