VB.NET
VB.NET
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 VB.NET 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 New Chilkat.AuthGoogle
gAuth.AccessToken = "GOOGLE_DRIVE_ACCESS_TOKEN"
Dim rest As New Chilkat.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 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 Integer = gdCache.DeleteAll()
' Create a date/time object with an time 7 days from the current date/time.
Dim dtExpire As New Chilkat.CkDateTime
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 New Chilkat.JsonObject
Dim jsonMasterArr As New Chilkat.JsonArray
jsonMaster.AppendArray2("fileIds",jsonMasterArr)
' Also keep a list of file paths.
Dim jsonMasterPaths As New Chilkat.JsonArray
jsonMaster.AppendArray2("filePaths",jsonMasterPaths)
' The default page size is 100, with a max of 1000.
rest.AddQueryParam("pageSize","200")
Dim json As New Chilkat.JsonObject
Dim jsonFileMetadata As Chilkat.JsonObject
Dim i As Integer
Dim numFiles As Integer
' Send the request for the 1st page.
Dim jsonResponse As String = rest.FullRequestNoBody("GET","/drive/v3/files")
Dim pageNumber As Integer = 1
Dim pageToken As String
Dim bContinueLoop As Boolean = rest.LastMethodSuccess And (rest.ResponseStatusCode = 200)
While bContinueLoop = True
Debug.WriteLine("---- Page " & pageNumber & " ----")
json.Load(jsonResponse)
numFiles = json.SizeOfArray("files")
i = 0
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
End While
' 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
End While
' Check to see if the above loop exited with errors...
If (rest.LastMethodSuccess = False) Then
Debug.WriteLine(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.WriteLine("response status code = " & rest.ResponseStatusCode)
Debug.WriteLine("response status text = " & rest.ResponseStatusText)
Debug.WriteLine("response header: " & rest.ResponseHeader)
Debug.WriteLine("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 Chilkat.Hashtable
' Set the capacity of the hash table to something reasonable for the number of files
' to be hashed.
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]")
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())
Debug.WriteLine(json.StringOf("name") & ", " & json.StringOf("parents[0]"))
i = i + 1
End While
' Check to see if the above loop exited with errors...
If (rest.LastMethodSuccess = False) Then
Debug.WriteLine(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.WriteLine("response status code = " & rest.ResponseStatusCode)
Debug.WriteLine("response status text = " & rest.ResponseStatusText)
Debug.WriteLine("response header: " & rest.ResponseHeader)
Debug.WriteLine("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.WriteLine("---- 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 = False
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
End While
Debug.WriteLine(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
End While
' 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)
Debug.WriteLine("JSON Master Record:")
Debug.WriteLine(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.WriteLine("Entire cache rebuilt...")