B4X Requires Chilkat v11.0.0+
B4X
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.Chilkat B4X Downloads
Dim success As Boolean = 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 ChilkatAuthGoogle
gAuth.Initialize("gAuth")
gAuth.AccessToken = "GOOGLE_DRIVE_ACCESS_TOKEN"
Dim rest As ChilkatRest
rest.Initialize("rest")
' Connect using TLS.
Dim bAutoReconnect As Boolean = True
success = rest.Connect("www.googleapis.com", 443, True, bAutoReconnect)
' Provide the authentication credentials (i.e. the access token)
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 ChilkatCache
gdCache.Initialize
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 Int = gdCache.DeleteAll
' Create a date/time object with an time 7 days from the current date/time.
Dim dtExpire As ChilkatDateTime
dtExpire.Initialize
dtExpire.SetFromCurrentSystemTime
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 = "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 ChilkatJsonObject
jsonMaster.Initialize
Dim jsonMasterArr As ChilkatJsonArray
jsonMasterArr.Initialize
jsonMaster.AppendArray2("fileIds", jsonMasterArr)
' Also keep a list of file paths.
Dim jsonMasterPaths As ChilkatJsonArray
jsonMasterPaths.Initialize
jsonMaster.AppendArray2("filePaths", jsonMasterPaths)
' The default page size is 100, with a max of 1000.
rest.AddQueryParam("pageSize", "200")
Dim json As ChilkatJsonObject
json.Initialize
Dim jsonFileMetadata As ChilkatJsonObject
Dim i As Int
Dim numFiles As Int
' Send the request for the 1st page.
Dim jsonResponse As String = rest.FullRequestNoBody("GET", "/drive/v3/files")
Dim pageNumber As Int = 1
Dim pageToken As String
Dim bContinueLoop As Boolean = rest.LastMethodSuccess And (rest.ResponseStatusCode = 200)
Do While bContinueLoop = True
Log("---- Page " & pageNumber & " ----")
json.Load(jsonResponse)
numFiles = json.SizeOfArray("files")
i = 0
Do While i < numFiles
' Add this file ID to the master list.
json.I = i
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 = False
Dim bHasMorePages As Boolean = json.LastMethodSuccess
If bHasMorePages = True Then
rest.ClearAllQueryParams
rest.AddQueryParam("pageSize", "200")
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 = False Then
Log(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
Log("response status code = " & rest.ResponseStatusCode)
Log("response status text = " & rest.ResponseStatusText)
Log("response header: " & rest.ResponseHeader)
Log("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 ChilkatHashtable
hashTable.Initialize
' Set the capacity of the hash table to something reasonable for the number of files
' to be hashed.
hashTable.ClearWithNewCapacity(521)
Dim sbPathForFileId As ChilkatStringBuilder
sbPathForFileId.Initialize
' Used for storing the file name and parents[0] in the hashTable.
Dim saFileInfo As ChilkatStringArray
saFileInfo.Initialize
saFileInfo.Unique = False
Dim fileId As String
numFiles = jsonMaster.SizeOfArray("fileIds")
i = 0
Do While i < numFiles
jsonMaster.I = i
fileId = jsonMaster.StringOf("fileIds[i]")
sbPathForFileId.SetString("/drive/v3/files/")
sbPathForFileId.Append(fileId)
rest.ClearAllQueryParams
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.
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..
json.Load(jsonResponse)
saFileInfo.Clear
saFileInfo.Append(json.StringOf("name"))
saFileInfo.Append(json.StringOf("parents[0]"))
hashTable.AddStr(fileId, saFileInfo.Serialize)
Log(json.StringOf("name") & ", " & json.StringOf("parents[0]"))
i = i + 1
Loop
' Check to see if the above loop exited with errors...
If rest.LastMethodSuccess = False Then
Log(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
Log("response status code = " & rest.ResponseStatusCode)
Log("response status text = " & rest.ResponseStatusText)
Log("response header: " & rest.ResponseHeader)
Log("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"
'
Log("---- building paths ----")
Dim sbPath As ChilkatStringBuilder
sbPath.Initialize
numFiles = jsonMaster.SizeOfArray("fileIds")
i = 0
Do While i < numFiles
jsonMaster.I = i
sbPath.Clear
fileId = jsonMaster.StringOf("fileIds[i]")
Dim bFinished As Boolean = False
Do While (bFinished = False)
saFileInfo.Clear
saFileInfo.AppendSerialized(hashTable.LookupStr(fileId))
' Append this file or directory name.
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
sbPath.Prepend("/")
End If
Loop
Log(i & ": " & sbPath.GetAsString)
' Store the filePath --> fileId mapping in our local cache.
fileId = jsonMaster.StringOf("fileIds[i]")
gdCache.SaveTextDt(sbPath.GetAsString, dtExpire, "", fileId)
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 = False
Dim strJsonMaster As String = jsonMaster.Emit
gdCache.SaveTextNoExpire("AllGoogleDriveFileIds", "", strJsonMaster)
Log("JSON Master Record:")
Log(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",
' ]
' }
Log("Entire cache rebuilt...")