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(Xojo Plugin) 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 Xojo Plugin Download

Xojo Plugin for Windows, Linux, Mac OS X, and ARM

Dim success As Boolean
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 Chilkat.JsonArray
jsonMasterArr = jsonMaster.AppendArray("fileIds")
//  Also keep a list of file paths.
Dim jsonMasterPaths As Chilkat.JsonArray
jsonMasterPaths = jsonMaster.AppendArray("filePaths")

//  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 <> True) 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 <> True) 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...")

 

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