Xbase++ Requires Chilkat v11.0.0+
Xbase++
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 Xbase++ Downloads
LOCAL nSuccess
LOCAL oGAuth
LOCAL oRest
LOCAL nBAutoReconnect
LOCAL oGdCache
LOCAL nNumCacheFilesDeleted
LOCAL oDtExpire
LOCAL cAllFields
LOCAL oJsonMaster
LOCAL oJsonMasterArr
LOCAL oJsonMasterPaths
LOCAL oJson
LOCAL oJsonFileMetadata
LOCAL i
LOCAL nNumFiles
LOCAL cJsonResponse
LOCAL nPageNumber
LOCAL cPageToken
LOCAL nBContinueLoop
LOCAL nBHasMorePages
LOCAL oHashTable
LOCAL oSbPathForFileId
LOCAL oSaFileInfo
LOCAL cFileId
LOCAL oSbPath
LOCAL nBFinished
LOCAL cStrJsonMaster
nSuccess := 0
nSuccess := 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.
oGAuth := CreateObject("Chilkat.AuthGoogle")
oGAuth:AccessToken := "GOOGLE_DRIVE_ACCESS_TOKEN"
oRest := CreateObject("Chilkat.Rest")
// Connect using TLS.
nBAutoReconnect := 1
nSuccess := oRest:Connect("www.googleapis.com", 443, 1, nBAutoReconnect)
// Provide the authentication credentials (i.e. the access token)
oRest:SetAuthGoogle(oGAuth)
// -------------------------------------------------------------------
// 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.
oGdCache := CreateObject("Chilkat.Cache")
oGdCache:Level := 0
// Use a root directory that makes sense on your operating system..
oGdCache:AddRoot("C:/ckCache/googleDrive")
// If we are re-building the cache, we can first delete the entire contents of the cache.
nNumCacheFilesDeleted := oGdCache:DeleteAll()
// Create a date/time object with an time 7 days from the current date/time.
oDtExpire := CreateObject("Chilkat.CkDateTime")
oDtExpire:SetFromCurrentSystemTime()
oDtExpire:AddDays(7)
// Indicate that we want ALL possible fields.
// If no fields are indicated, then only the basic fields are returned.
cAllFields := "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".
oJsonMaster := CreateObject("Chilkat.JsonObject")
oJsonMasterArr := CreateObject("Chilkat.JsonArray")
oJsonMaster:AppendArray2("fileIds", oJsonMasterArr)
// Also keep a list of file paths.
oJsonMasterPaths := CreateObject("Chilkat.JsonArray")
oJsonMaster:AppendArray2("filePaths", oJsonMasterPaths)
// The default page size is 100, with a max of 1000.
oRest:AddQueryParam("pageSize", "200")
oJson := CreateObject("Chilkat.JsonObject")
// Send the request for the 1st page.
cJsonResponse := oRest:FullRequestNoBody("GET", "/drive/v3/files")
nPageNumber := 1
nBContinueLoop := oRest:LastMethodSuccess .AND. (oRest:ResponseStatusCode == 200)
DO WHILE nBContinueLoop == 1
? "---- Page " + Str(nPageNumber) + " ----"
oJson:Load(cJsonResponse)
nNumFiles := oJson:SizeOfArray("files")
i := 0
DO WHILE i < nNumFiles
// Add this file ID to the master list.
oJson:I := i
oJsonMasterArr:AddStringAt(-1, oJson:StringOf("files[i].id"))
i := i + 1
ENDDO
// 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.
cPageToken := oJson:StringOf("nextPageToken")
nBContinueLoop := 0
nBHasMorePages := oJson:LastMethodSuccess
IF (nBHasMorePages == 1)
oRest:ClearAllQueryParams()
oRest:AddQueryParam("pageSize", "200")
oRest:AddQueryParam("pageToken", cPageToken)
cJsonResponse := oRest:FullRequestNoBody("GET", "/drive/v3/files")
nBContinueLoop := oRest:LastMethodSuccess .AND. (oRest:ResponseStatusCode == 200)
nPageNumber := nPageNumber + 1
ENDIF
ENDDO
// Check to see if the above loop exited with errors...
IF (oRest:LastMethodSuccess == 0)
? oRest:LastErrorText
oGAuth:destroy()
oRest:destroy()
oGdCache:destroy()
oDtExpire:destroy()
oJsonMaster:destroy()
oJsonMasterArr:destroy()
oJsonMasterPaths:destroy()
oJson:destroy()
RETURN
ENDIF
// Check to see if the above loop exited with errors...
// A successful response will have a status code equal to 200.
IF (oRest:ResponseStatusCode != 200)
? "response status code = " + Str(oRest:ResponseStatusCode)
? "response status text = " + oRest:ResponseStatusText
? "response header: " + oRest:ResponseHeader
? "response JSON: " + cJsonResponse
oGAuth:destroy()
oRest:destroy()
oGdCache:destroy()
oDtExpire:destroy()
oJsonMaster:destroy()
oJsonMasterArr:destroy()
oJsonMasterPaths:destroy()
oJson:destroy()
RETURN
ENDIF
// 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.)
oHashTable := CreateObject("Chilkat.Hashtable")
// Set the capacity of the hash table to something reasonable for the number of files
// to be hashed.
oHashTable:ClearWithNewCapacity(521)
oSbPathForFileId := CreateObject("Chilkat.StringBuilder")
// Used for storing the file name and parents[0] in the hashTable.
oSaFileInfo := CreateObject("Chilkat.StringArray")
oSaFileInfo:Unique := 0
nNumFiles := oJsonMaster:SizeOfArray("fileIds")
i := 0
DO WHILE i < nNumFiles
oJsonMaster:I := i
cFileId := oJsonMaster:StringOf("fileIds[i]")
oSbPathForFileId:SetString("/drive/v3/files/")
oSbPathForFileId:Append(cFileId)
oRest:ClearAllQueryParams()
oRest:AddQueryParam("fields", cAllFields)
cJsonResponse := oRest:FullRequestNoBody("GET", oSbPathForFileId:GetAsString())
IF ((oRest:LastMethodSuccess != 1) .OR. (oRest:ResponseStatusCode != 200))
// Force an exit of this loop..
nNumFiles := 0
ENDIF
// Save this file's metadata to the local cache.
// The lookup key is the fileId.
oGdCache:SaveTextDt(cFileId, oDtExpire, "", cJsonResponse)
// Get this file's name and parent[0], and put this information
// in our in-memory hashtable to be used below..
oJson:Load(cJsonResponse)
oSaFileInfo:Clear()
oSaFileInfo:Append(oJson:StringOf("name"))
oSaFileInfo:Append(oJson:StringOf("parents[0]"))
oHashTable:AddStr(cFileId, oSaFileInfo:Serialize())
? oJson:StringOf("name") + ", " + oJson:StringOf("parents[0]")
i := i + 1
ENDDO
// Check to see if the above loop exited with errors...
IF (oRest:LastMethodSuccess == 0)
? oRest:LastErrorText
oGAuth:destroy()
oRest:destroy()
oGdCache:destroy()
oDtExpire:destroy()
oJsonMaster:destroy()
oJsonMasterArr:destroy()
oJsonMasterPaths:destroy()
oJson:destroy()
oHashTable:destroy()
oSbPathForFileId:destroy()
oSaFileInfo:destroy()
RETURN
ENDIF
// Check to see if the above loop exited with errors...
// A successful response will have a status code equal to 200.
IF (oRest:ResponseStatusCode != 200)
? "response status code = " + Str(oRest:ResponseStatusCode)
? "response status text = " + oRest:ResponseStatusText
? "response header: " + oRest:ResponseHeader
? "response JSON: " + cJsonResponse
oGAuth:destroy()
oRest:destroy()
oGdCache:destroy()
oDtExpire:destroy()
oJsonMaster:destroy()
oJsonMasterArr:destroy()
oJsonMasterPaths:destroy()
oJson:destroy()
oHashTable:destroy()
oSbPathForFileId:destroy()
oSaFileInfo:destroy()
RETURN
ENDIF
// 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"
//
? "---- building paths ----"
oSbPath := CreateObject("Chilkat.StringBuilder")
nNumFiles := oJsonMaster:SizeOfArray("fileIds")
i := 0
DO WHILE i < nNumFiles
oJsonMaster:I := i
oSbPath:Clear()
cFileId := oJsonMaster:StringOf("fileIds[i]")
nBFinished := 0
DO WHILE (nBFinished == 0)
oSaFileInfo:Clear()
oSaFileInfo:AppendSerialized(oHashTable:LookupStr(cFileId))
// Append this file or directory name.
oSbPath:Prepend(oSaFileInfo:GetString(0))
// Get the parent fileId
cFileId := oSaFileInfo:GetString(1)
// If this fileId is not in the hashtable, then it's the fileId for "My Drive", and we are finished.
IF (oHashTable:Contains(cFileId) == 0)
nBFinished := 1
ELSE
oSbPath:Prepend("/")
ENDIF
ENDDO
? Str(i) + ": " + oSbPath:GetAsString()
// Store the filePath --> fileId mapping in our local cache.
cFileId := oJsonMaster:StringOf("fileIds[i]")
oGdCache:SaveTextDt(oSbPath:GetAsString(), oDtExpire, "", cFileId)
oJsonMasterPaths:AddStringAt(-1, oSbPath:GetAsString())
i := i + 1
ENDDO
// Save the master list of file IDs and file paths to the local cache.
oJsonMaster:EmitCompact := 0
cStrJsonMaster := oJsonMaster:Emit()
oGdCache:SaveTextNoExpire("AllGoogleDriveFileIds", "", cStrJsonMaster)
? "JSON Master Record:"
? cStrJsonMaster
// 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",
// ]
// }
? "Entire cache rebuilt..."
oGAuth:destroy()
oRest:destroy()
oGdCache:destroy()
oDtExpire:destroy()
oJsonMaster:destroy()
oJsonMasterArr:destroy()
oJsonMasterPaths:destroy()
oJson:destroy()
oHashTable:destroy()
oSbPathForFileId:destroy()
oSaFileInfo:destroy()
oSbPath:destroy()