Dart Requires Chilkat v11.0.0+
Dart
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 Dart Downloads
import 'package:chilkat/chilkat.dart';
void main() {
// 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.
final gAuth = CkAuthGoogle();
gAuth.accessToken = 'GOOGLE_DRIVE_ACCESS_TOKEN';
final rest = CkRest();
// Connect using TLS.
final bAutoReconnect = true;
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.
final gdCache = CkCache();
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.
final numCacheFilesDeleted = gdCache.deleteAll();
// Create a date/time object with an time 7 days from the current date/time.
final dtExpire = 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.
final 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".
final jsonMaster = CkJsonObject();
final jsonMasterArr = CkJsonArray();
jsonMaster.appendArray2('fileIds', jsonMasterArr);
// Also keep a list of file paths.
final jsonMasterPaths = CkJsonArray();
jsonMaster.appendArray2('filePaths', jsonMasterPaths);
// The default page size is 100, with a max of 1000.
rest.addQueryParam('pageSize', '200');
final json = CkJsonObject();
final jsonFileMetadata = CkJsonObject();
var i = 0;
var numFiles = 0;
// Send the request for the 1st page.
var jsonResponse = rest.fullRequestNoBody('GET', '/drive/v3/files');
var pageNumber = 1;
var pageToken = '';
var bContinueLoop = rest.lastMethodSuccess && (rest.responseStatusCode == 200);
while (bContinueLoop) {
print('---- 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++;
}
// 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;
final bHasMorePages = json.lastMethodSuccess;
if (bHasMorePages) {
rest.clearAllQueryParams();
rest.addQueryParam('pageSize', '200');
rest.addQueryParam('pageToken', pageToken);
jsonResponse = rest.fullRequestNoBody('GET', '/drive/v3/files');
bContinueLoop = rest.lastMethodSuccess && (rest.responseStatusCode == 200);
pageNumber++;
}
}
// Check to see if the above loop exited with errors...
if (!rest.lastMethodSuccess) {
print(rest.lastErrorText);
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) {
print('response status code = ${rest.responseStatusCode}');
print('response status text = ${rest.responseStatusText}');
print('response header: ${rest.responseHeader}');
print('response JSON: $jsonResponse');
return;
}
// Iterate over the file IDs and download the metadata for each, saving each to the cache...
// Also, keep in-memory hash entries of the name and parent[0] so we can quickly
// build the path-->fileId cache entries. (Given that the Google Drive REST API uses
// fileIds, this gives us an easy way to lookup a fileId based on a filePath.)
final hashTable = CkHashtable();
// Set the capacity of the hash table to something reasonable for the number of files
// to be hashed.
hashTable.clearWithNewCapacity(521);
final sbPathForFileId = CkStringBuilder();
// Used for storing the file name and parents[0] in the hashTable.
final saFileInfo = CkStringArray();
saFileInfo.unique = false;
var fileId = '';
numFiles = jsonMaster.sizeOfArray('fileIds');
i = 0;
while (i < numFiles) {
jsonMaster.i = i;
fileId = jsonMaster.stringOf('fileIds[i]');
sbPathForFileId.setString('/drive/v3/files/');
sbPathForFileId.append(fileId);
rest.clearAllQueryParams();
rest.addQueryParam('fields', allFields);
jsonResponse = rest.fullRequestNoBody('GET', sbPathForFileId.getAsString());
if ((!rest.lastMethodSuccess) || (rest.responseStatusCode != 200)) {
// Force an exit of this loop..
numFiles = 0;
}
// Save this file's metadata to the local cache.
// The lookup key is the fileId.
gdCache.saveTextDt(fileId, dtExpire, '', jsonResponse);
// Get this file's name and parent[0], and put this information
// in our in-memory hashtable to be used below..
json.load(jsonResponse);
saFileInfo.clear();
saFileInfo.append(json.stringOf('name'));
saFileInfo.append(json.stringOf('parents[0]'));
hashTable.addStr(fileId, saFileInfo.serialize());
print('${json.stringOf('name')}, ${json.stringOf('parents[0]')}');
i++;
}
// Check to see if the above loop exited with errors...
if (!rest.lastMethodSuccess) {
print(rest.lastErrorText);
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) {
print('response status code = ${rest.responseStatusCode}');
print('response status text = ${rest.responseStatusText}');
print('response header: ${rest.responseHeader}');
print('response JSON: $jsonResponse');
return;
}
// Now that all the fileId's are in the cache, let's build the directory path
// for each fileID.
// (Technically, a fileId can have multiple parents, which means it can be in multiple directories
// at once. This is only going to build directory paths following the 0'th parent ID in the parents list.)
// The directory path for files in "My Drive" will be just the filename.
// For files in sub-directories, the path will be relative, such as "subdir1/subdir2/something.pdf"
//
print('---- building paths ----');
final sbPath = CkStringBuilder();
numFiles = jsonMaster.sizeOfArray('fileIds');
i = 0;
while (i < numFiles) {
jsonMaster.i = i;
sbPath.clear();
fileId = jsonMaster.stringOf('fileIds[i]');
var bFinished = false;
while (!bFinished) {
saFileInfo.clear();
saFileInfo.appendSerialized(hashTable.lookupStr(fileId));
// Append this file or directory name.
sbPath.prepend(saFileInfo.getString(0));
// Get the parent fileId
fileId = saFileInfo.getString(1);
// If this fileId is not in the hashtable, then it's the fileId for "My Drive", and we are finished.
if (!hashTable.contains(fileId)) {
bFinished = true;
} else {
sbPath.prepend('/');
}
}
print('$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++;
}
// Save the master list of file IDs and file paths to the local cache.
jsonMaster.emitCompact = false;
final strJsonMaster = jsonMaster.emit();
gdCache.saveTextNoExpire('AllGoogleDriveFileIds', '', strJsonMaster);
print('JSON Master Record:');
print(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",
// ]
// }
print('Entire cache rebuilt...');
}