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
#include <C_CkAuthGoogle.h>
#include <C_CkRest.h>
#include <C_CkCache.h>
#include <C_CkDateTime.h>
#include <C_CkJsonObject.h>
#include <C_CkJsonArray.h>
#include <C_CkHashtable.h>
#include <C_CkStringBuilder.h>
#include <C_CkStringArray.h>
void ChilkatSample(void)
{
BOOL success;
HCkAuthGoogle gAuth;
HCkRest rest;
BOOL bAutoReconnect;
HCkCache gdCache;
int numCacheFilesDeleted;
HCkDateTime dtExpire;
const char *allFields;
HCkJsonObject jsonMaster;
HCkJsonArray jsonMasterArr;
HCkJsonArray jsonMasterPaths;
HCkJsonObject json;
HCkJsonObject jsonFileMetadata;
int i;
int numFiles;
const char *jsonResponse;
int pageNumber;
const char *pageToken;
BOOL bContinueLoop;
BOOL bHasMorePages;
HCkHashtable hashTable;
HCkStringBuilder sbPathForFileId;
HCkStringArray saFileInfo;
const char *fileId;
HCkStringBuilder sbPath;
BOOL bFinished;
const char *strJsonMaster;
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 = CkAuthGoogle_Create();
CkAuthGoogle_putAccessToken(gAuth,"GOOGLE_DRIVE_ACCESS_TOKEN");
rest = CkRest_Create();
// Connect using TLS.
bAutoReconnect = TRUE;
success = CkRest_Connect(rest,"www.googleapis.com",443,TRUE,bAutoReconnect);
// Provide the authentication credentials (i.e. the access token)
CkRest_SetAuthGoogle(rest,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 = CkCache_Create();
CkCache_putLevel(gdCache,0);
// Use a root directory that makes sense on your operating system..
CkCache_AddRoot(gdCache,"C:/ckCache/googleDrive");
// If we are re-building the cache, we can first delete the entire contents of the cache.
numCacheFilesDeleted = CkCache_DeleteAll(gdCache);
// Create a date/time object with an time 7 days from the current date/time.
dtExpire = CkDateTime_Create();
CkDateTime_SetFromCurrentSystemTime(dtExpire);
CkDateTime_AddDays(dtExpire,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 = CkJsonObject_Create();
jsonMasterArr = CkJsonArray_Create();
CkJsonObject_AppendArray2(jsonMaster,"fileIds",jsonMasterArr);
// Also keep a list of file paths.
jsonMasterPaths = CkJsonArray_Create();
CkJsonObject_AppendArray2(jsonMaster,"filePaths",jsonMasterPaths);
// The default page size is 100, with a max of 1000.
CkRest_AddQueryParam(rest,"pageSize","200");
json = CkJsonObject_Create();
// Send the request for the 1st page.
jsonResponse = CkRest_fullRequestNoBody(rest,"GET","/drive/v3/files");
pageNumber = 1;
bContinueLoop = CkRest_getLastMethodSuccess(rest) && (CkRest_getResponseStatusCode(rest) == 200);
while (bContinueLoop == TRUE) {
printf("---- Page %d ----\n",pageNumber);
CkJsonObject_Load(json,jsonResponse);
numFiles = CkJsonObject_SizeOfArray(json,"files");
i = 0;
while (i < numFiles) {
// Add this file ID to the master list.
CkJsonObject_putI(json,i);
CkJsonArray_AddStringAt(jsonMasterArr,-1,CkJsonObject_stringOf(json,"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 = CkJsonObject_stringOf(json,"nextPageToken");
bContinueLoop = FALSE;
bHasMorePages = CkJsonObject_getLastMethodSuccess(json);
if (bHasMorePages == TRUE) {
CkRest_ClearAllQueryParams(rest);
CkRest_AddQueryParam(rest,"pageSize","200");
CkRest_AddQueryParam(rest,"pageToken",pageToken);
jsonResponse = CkRest_fullRequestNoBody(rest,"GET","/drive/v3/files");
bContinueLoop = CkRest_getLastMethodSuccess(rest) && (CkRest_getResponseStatusCode(rest) == 200);
pageNumber = pageNumber + 1;
}
}
// Check to see if the above loop exited with errors...
if (CkRest_getLastMethodSuccess(rest) == FALSE) {
printf("%s\n",CkRest_lastErrorText(rest));
CkAuthGoogle_Dispose(gAuth);
CkRest_Dispose(rest);
CkCache_Dispose(gdCache);
CkDateTime_Dispose(dtExpire);
CkJsonObject_Dispose(jsonMaster);
CkJsonArray_Dispose(jsonMasterArr);
CkJsonArray_Dispose(jsonMasterPaths);
CkJsonObject_Dispose(json);
return;
}
// Check to see if the above loop exited with errors...
// A successful response will have a status code equal to 200.
if (CkRest_getResponseStatusCode(rest) != 200) {
printf("response status code = %d\n",CkRest_getResponseStatusCode(rest));
printf("response status text = %s\n",CkRest_responseStatusText(rest));
printf("response header: %s\n",CkRest_responseHeader(rest));
printf("response JSON: %s\n",jsonResponse);
CkAuthGoogle_Dispose(gAuth);
CkRest_Dispose(rest);
CkCache_Dispose(gdCache);
CkDateTime_Dispose(dtExpire);
CkJsonObject_Dispose(jsonMaster);
CkJsonArray_Dispose(jsonMasterArr);
CkJsonArray_Dispose(jsonMasterPaths);
CkJsonObject_Dispose(json);
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 = CkHashtable_Create();
// Set the capacity of the hash table to something reasonable for the number of files
// to be hashed.
CkHashtable_ClearWithNewCapacity(hashTable,521);
sbPathForFileId = CkStringBuilder_Create();
// Used for storing the file name and parents[0] in the hashTable.
saFileInfo = CkStringArray_Create();
CkStringArray_putUnique(saFileInfo,FALSE);
numFiles = CkJsonObject_SizeOfArray(jsonMaster,"fileIds");
i = 0;
while (i < numFiles) {
CkJsonObject_putI(jsonMaster,i);
fileId = CkJsonObject_stringOf(jsonMaster,"fileIds[i]");
CkStringBuilder_SetString(sbPathForFileId,"/drive/v3/files/");
CkStringBuilder_Append(sbPathForFileId,fileId);
CkRest_ClearAllQueryParams(rest);
CkRest_AddQueryParam(rest,"fields",allFields);
jsonResponse = CkRest_fullRequestNoBody(rest,"GET",CkStringBuilder_getAsString(sbPathForFileId));
if ((CkRest_getLastMethodSuccess(rest) != TRUE) || (CkRest_getResponseStatusCode(rest) != 200)) {
// Force an exit of this loop..
numFiles = 0;
}
// Save this file's metadata to the local cache.
// The lookup key is the fileId.
CkCache_SaveTextDt(gdCache,fileId,dtExpire,"",jsonResponse);
// Get this file's name and parent[0], and put this information
// in our in-memory hashtable to be used below..
CkJsonObject_Load(json,jsonResponse);
CkStringArray_Clear(saFileInfo);
CkStringArray_Append(saFileInfo,CkJsonObject_stringOf(json,"name"));
CkStringArray_Append(saFileInfo,CkJsonObject_stringOf(json,"parents[0]"));
CkHashtable_AddStr(hashTable,fileId,CkStringArray_serialize(saFileInfo));
printf("%s, %s\n",CkJsonObject_stringOf(json,"name"),CkJsonObject_stringOf(json,"parents[0]"));
i = i + 1;
}
// Check to see if the above loop exited with errors...
if (CkRest_getLastMethodSuccess(rest) == FALSE) {
printf("%s\n",CkRest_lastErrorText(rest));
CkAuthGoogle_Dispose(gAuth);
CkRest_Dispose(rest);
CkCache_Dispose(gdCache);
CkDateTime_Dispose(dtExpire);
CkJsonObject_Dispose(jsonMaster);
CkJsonArray_Dispose(jsonMasterArr);
CkJsonArray_Dispose(jsonMasterPaths);
CkJsonObject_Dispose(json);
CkHashtable_Dispose(hashTable);
CkStringBuilder_Dispose(sbPathForFileId);
CkStringArray_Dispose(saFileInfo);
return;
}
// Check to see if the above loop exited with errors...
// A successful response will have a status code equal to 200.
if (CkRest_getResponseStatusCode(rest) != 200) {
printf("response status code = %d\n",CkRest_getResponseStatusCode(rest));
printf("response status text = %s\n",CkRest_responseStatusText(rest));
printf("response header: %s\n",CkRest_responseHeader(rest));
printf("response JSON: %s\n",jsonResponse);
CkAuthGoogle_Dispose(gAuth);
CkRest_Dispose(rest);
CkCache_Dispose(gdCache);
CkDateTime_Dispose(dtExpire);
CkJsonObject_Dispose(jsonMaster);
CkJsonArray_Dispose(jsonMasterArr);
CkJsonArray_Dispose(jsonMasterPaths);
CkJsonObject_Dispose(json);
CkHashtable_Dispose(hashTable);
CkStringBuilder_Dispose(sbPathForFileId);
CkStringArray_Dispose(saFileInfo);
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"
//
printf("---- building paths ----\n");
sbPath = CkStringBuilder_Create();
numFiles = CkJsonObject_SizeOfArray(jsonMaster,"fileIds");
i = 0;
while (i < numFiles) {
CkJsonObject_putI(jsonMaster,i);
CkStringBuilder_Clear(sbPath);
fileId = CkJsonObject_stringOf(jsonMaster,"fileIds[i]");
bFinished = FALSE;
while ((bFinished == FALSE)) {
CkStringArray_Clear(saFileInfo);
CkStringArray_AppendSerialized(saFileInfo,CkHashtable_lookupStr(hashTable,fileId));
// Append this file or directory name.
CkStringBuilder_Prepend(sbPath,CkStringArray_getString(saFileInfo,0));
// Get the parent fileId
fileId = CkStringArray_getString(saFileInfo,1);
// If this fileId is not in the hashtable, then it's the fileId for "My Drive", and we are finished.
if (CkHashtable_Contains(hashTable,fileId) == FALSE) {
bFinished = TRUE;
}
else {
CkStringBuilder_Prepend(sbPath,"/");
}
}
printf("%d: %s\n",i,CkStringBuilder_getAsString(sbPath));
// Store the filePath --> fileId mapping in our local cache.
fileId = CkJsonObject_stringOf(jsonMaster,"fileIds[i]");
CkCache_SaveTextDt(gdCache,CkStringBuilder_getAsString(sbPath),dtExpire,"",fileId);
CkJsonArray_AddStringAt(jsonMasterPaths,-1,CkStringBuilder_getAsString(sbPath));
i = i + 1;
}
// Save the master list of file IDs and file paths to the local cache.
CkJsonObject_putEmitCompact(jsonMaster,FALSE);
strJsonMaster = CkJsonObject_emit(jsonMaster);
CkCache_SaveTextNoExpire(gdCache,"AllGoogleDriveFileIds","",strJsonMaster);
printf("JSON Master Record:\n");
printf("%s\n",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",
// ]
// }
printf("Entire cache rebuilt...\n");
CkAuthGoogle_Dispose(gAuth);
CkRest_Dispose(rest);
CkCache_Dispose(gdCache);
CkDateTime_Dispose(dtExpire);
CkJsonObject_Dispose(jsonMaster);
CkJsonArray_Dispose(jsonMasterArr);
CkJsonArray_Dispose(jsonMasterPaths);
CkJsonObject_Dispose(json);
CkHashtable_Dispose(hashTable);
CkStringBuilder_Dispose(sbPathForFileId);
CkStringArray_Dispose(saFileInfo);
CkStringBuilder_Dispose(sbPath);
}