Go Requires Chilkat v11.0.0+
Go
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 Go Downloads
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.
gAuth := chilkat.NewAuthGoogle()
gAuth.SetAccessToken("GOOGLE_DRIVE_ACCESS_TOKEN")
rest := chilkat.NewRest()
// Connect using TLS.
bAutoReconnect := 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.
gdCache := chilkat.NewCache()
gdCache.SetLevel(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.
numCacheFilesDeleted := gdCache.DeleteAll()
// Create a date/time object with an time 7 days from the current date/time.
dtExpire := chilkat.NewCkDateTime()
dtExpire.SetFromCurrentSystemTime()
dtExpire.AddDays(7)
// Indicate that we want ALL possible fields.
// If no fields are indicated, then only the basic fields are returned.
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".
jsonMaster := chilkat.NewJsonObject()
jsonMasterArr := chilkat.NewJsonArray()
jsonMaster.AppendArray2("fileIds",jsonMasterArr)
// Also keep a list of file paths.
jsonMasterPaths := chilkat.NewJsonArray()
jsonMaster.AppendArray2("filePaths",jsonMasterPaths)
// The default page size is 100, with a max of 1000.
rest.AddQueryParam("pageSize","200")
json := chilkat.NewJsonObject()
// jsonFileMetadata is a JsonObject
var i int
var numFiles int
// Send the request for the 1st page.
jsonResponse := rest.FullRequestNoBody("GET","/drive/v3/files")
pageNumber := 1
var pageToken *string = new(string)
bContinueLoop := rest.LastMethodSuccess() && (rest.ResponseStatusCode() == 200)
for bContinueLoop == true {
fmt.Println("---- Page ", pageNumber, " ----")
json.Load(*jsonResponse)
numFiles = json.SizeOfArray("files")
i = 0
for i < numFiles {
// Add this file ID to the master list.
json.SetI(i)
jsonMasterArr.AddStringAt(-1,*json.StringOf("files[i].id"))
i = i + 1
}
// 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
bHasMorePages := json.LastMethodSuccess()
if bHasMorePages == true {
rest.ClearAllQueryParams()
rest.AddQueryParam("pageSize","200")
rest.AddQueryParam("pageToken",*pageToken)
jsonResponse = rest.FullRequestNoBody("GET","/drive/v3/files")
bContinueLoop = rest.LastMethodSuccess() && (rest.ResponseStatusCode() == 200)
pageNumber = pageNumber + 1
}
}
// Check to see if the above loop exited with errors...
if rest.LastMethodSuccess() == false {
fmt.Println(rest.LastErrorText())
gAuth.DisposeAuthGoogle()
rest.DisposeRest()
gdCache.DisposeCache()
dtExpire.DisposeCkDateTime()
jsonMaster.DisposeJsonObject()
jsonMasterArr.DisposeJsonArray()
jsonMasterPaths.DisposeJsonArray()
json.DisposeJsonObject()
return
}
// 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 {
fmt.Println("response status code = ", rest.ResponseStatusCode())
fmt.Println("response status text = ", rest.ResponseStatusText())
fmt.Println("response header: ", rest.ResponseHeader())
fmt.Println("response JSON: ", *jsonResponse)
gAuth.DisposeAuthGoogle()
rest.DisposeRest()
gdCache.DisposeCache()
dtExpire.DisposeCkDateTime()
jsonMaster.DisposeJsonObject()
jsonMasterArr.DisposeJsonArray()
jsonMasterPaths.DisposeJsonArray()
json.DisposeJsonObject()
return
}
// 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.)
hashTable := chilkat.NewHashtable()
// Set the capacity of the hash table to something reasonable for the number of files
// to be hashed.
hashTable.ClearWithNewCapacity(521)
sbPathForFileId := chilkat.NewStringBuilder()
// Used for storing the file name and parents[0] in the hashTable.
saFileInfo := chilkat.NewStringArray()
saFileInfo.SetUnique(false)
var fileId *string = new(string)
numFiles = jsonMaster.SizeOfArray("fileIds")
i = 0
for i < numFiles {
jsonMaster.SetI(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) || (rest.ResponseStatusCode() != 200) {
// Force an exit of this loop..
numFiles = 0
}
// 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())
fmt.Println(*json.StringOf("name"), ", ", *json.StringOf("parents[0]"))
i = i + 1
}
// Check to see if the above loop exited with errors...
if rest.LastMethodSuccess() == false {
fmt.Println(rest.LastErrorText())
gAuth.DisposeAuthGoogle()
rest.DisposeRest()
gdCache.DisposeCache()
dtExpire.DisposeCkDateTime()
jsonMaster.DisposeJsonObject()
jsonMasterArr.DisposeJsonArray()
jsonMasterPaths.DisposeJsonArray()
json.DisposeJsonObject()
hashTable.DisposeHashtable()
sbPathForFileId.DisposeStringBuilder()
saFileInfo.DisposeStringArray()
return
}
// 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 {
fmt.Println("response status code = ", rest.ResponseStatusCode())
fmt.Println("response status text = ", rest.ResponseStatusText())
fmt.Println("response header: ", rest.ResponseHeader())
fmt.Println("response JSON: ", *jsonResponse)
gAuth.DisposeAuthGoogle()
rest.DisposeRest()
gdCache.DisposeCache()
dtExpire.DisposeCkDateTime()
jsonMaster.DisposeJsonObject()
jsonMasterArr.DisposeJsonArray()
jsonMasterPaths.DisposeJsonArray()
json.DisposeJsonObject()
hashTable.DisposeHashtable()
sbPathForFileId.DisposeStringBuilder()
saFileInfo.DisposeStringArray()
return
}
// 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"
//
fmt.Println("---- building paths ----")
sbPath := chilkat.NewStringBuilder()
numFiles = jsonMaster.SizeOfArray("fileIds")
i = 0
for i < numFiles {
jsonMaster.SetI(i)
sbPath.Clear()
fileId = jsonMaster.StringOf("fileIds[i]")
bFinished := false
for (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 {
bFinished = true
} else {
sbPath.Prepend("/")
}
}
fmt.Println(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
}
// Save the master list of file IDs and file paths to the local cache.
jsonMaster.SetEmitCompact(false)
strJsonMaster := jsonMaster.Emit()
gdCache.SaveTextNoExpire("AllGoogleDriveFileIds","",*strJsonMaster)
fmt.Println("JSON Master Record:")
fmt.Println(*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",
// ]
// }
fmt.Println("Entire cache rebuilt...")
gAuth.DisposeAuthGoogle()
rest.DisposeRest()
gdCache.DisposeCache()
dtExpire.DisposeCkDateTime()
jsonMaster.DisposeJsonObject()
jsonMasterArr.DisposeJsonArray()
jsonMasterPaths.DisposeJsonArray()
json.DisposeJsonObject()
hashTable.DisposeHashtable()
sbPathForFileId.DisposeStringBuilder()
saFileInfo.DisposeStringArray()
sbPath.DisposeStringBuilder()