C#
C#
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 C# Downloads
bool 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.
Chilkat.AuthGoogle gAuth = new Chilkat.AuthGoogle();
gAuth.AccessToken = "GOOGLE_DRIVE_ACCESS_TOKEN";
Chilkat.Rest rest = new Chilkat.Rest();
// Connect using TLS.
bool 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.
Chilkat.Cache gdCache = 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.
int numCacheFilesDeleted = gdCache.DeleteAll();
// Create a date/time object with an time 7 days from the current date/time.
Chilkat.CkDateTime dtExpire = 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.
string 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".
Chilkat.JsonObject jsonMaster = new Chilkat.JsonObject();
Chilkat.JsonArray jsonMasterArr = new Chilkat.JsonArray();
jsonMaster.AppendArray2("fileIds",jsonMasterArr);
// Also keep a list of file paths.
Chilkat.JsonArray jsonMasterPaths = new Chilkat.JsonArray();
jsonMaster.AppendArray2("filePaths",jsonMasterPaths);
// The default page size is 100, with a max of 1000.
rest.AddQueryParam("pageSize","200");
Chilkat.JsonObject json = new Chilkat.JsonObject();
Chilkat.JsonObject jsonFileMetadata = null;
int i;
int numFiles;
// Send the request for the 1st page.
string jsonResponse = rest.FullRequestNoBody("GET","/drive/v3/files");
int pageNumber = 1;
string pageToken;
bool bContinueLoop = rest.LastMethodSuccess && (rest.ResponseStatusCode == 200);
while (bContinueLoop == true) {
Debug.WriteLine("---- Page " + Convert.ToString(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;
}
// 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;
bool 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) {
Debug.WriteLine(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) {
Debug.WriteLine("response status code = " + Convert.ToString(rest.ResponseStatusCode));
Debug.WriteLine("response status text = " + rest.ResponseStatusText);
Debug.WriteLine("response header: " + rest.ResponseHeader);
Debug.WriteLine("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.)
Chilkat.Hashtable hashTable = new Chilkat.Hashtable();
// Set the capacity of the hash table to something reasonable for the number of files
// to be hashed.
hashTable.ClearWithNewCapacity(521);
Chilkat.StringBuilder sbPathForFileId = new Chilkat.StringBuilder();
// Used for storing the file name and parents[0] in the hashTable.
Chilkat.StringArray saFileInfo = new Chilkat.StringArray();
saFileInfo.Unique = false;
string 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 != 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());
Debug.WriteLine(json.StringOf("name") + ", " + json.StringOf("parents[0]"));
i = i + 1;
}
// Check to see if the above loop exited with errors...
if (rest.LastMethodSuccess == false) {
Debug.WriteLine(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) {
Debug.WriteLine("response status code = " + Convert.ToString(rest.ResponseStatusCode));
Debug.WriteLine("response status text = " + rest.ResponseStatusText);
Debug.WriteLine("response header: " + rest.ResponseHeader);
Debug.WriteLine("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"
//
Debug.WriteLine("---- building paths ----");
Chilkat.StringBuilder sbPath = new Chilkat.StringBuilder();
numFiles = jsonMaster.SizeOfArray("fileIds");
i = 0;
while (i < numFiles) {
jsonMaster.I = i;
sbPath.Clear();
fileId = jsonMaster.StringOf("fileIds[i]");
bool bFinished = 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) {
bFinished = true;
}
else {
sbPath.Prepend("/");
}
}
Debug.WriteLine(Convert.ToString(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.EmitCompact = false;
string strJsonMaster = 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...");