(Unicode C++) Google Drive - Build a Local Cache of Metadata

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.

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#include <CkAuthGoogleW.h>
#include <CkRestW.h>
#include <CkCacheW.h>
#include <CkDateTimeW.h>
#include <CkJsonObjectW.h>
#include <CkJsonArrayW.h>
#include <CkHashtableW.h>
#include <CkStringBuilderW.h>
#include <CkStringArrayW.h>

void ChilkatSample(void)
    {
    bool 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.

    CkAuthGoogleW gAuth;
    gAuth.put_AccessToken(L"GOOGLE_DRIVE_ACCESS_TOKEN");

    CkRestW rest;

    // Connect using TLS.
    bool bAutoReconnect = true;
    success = rest.Connect(L"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.
    CkCacheW gdCache;
    gdCache.put_Level(0);
    // Use a root directory that makes sense on your operating system..
    gdCache.AddRoot(L"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.
    CkDateTimeW dtExpire;
    dtExpire.SetFromCurrentSystemTime();
    dtExpire.AddDays(7);

    // Indicate that we want ALL possible fields.
    // If no fields are indicated, then only the basic fields are returned.
    const wchar_t *allFields = L"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".
    CkJsonObjectW jsonMaster;
    CkJsonArrayW *jsonMasterArr = jsonMaster.AppendArray(L"fileIds");
    // Also keep a list of file paths.
    CkJsonArrayW *jsonMasterPaths = jsonMaster.AppendArray(L"filePaths");

    // The default page size is 100, with a max of 1000.
    rest.AddQueryParam(L"pageSize",L"200");

    CkJsonObjectW json;
    CkJsonObjectW *jsonFileMetadata = 0;
    int i;
    int numFiles;

    // Send the request for the 1st page.
    const wchar_t *jsonResponse = rest.fullRequestNoBody(L"GET",L"/drive/v3/files");

    int pageNumber = 1;
    const wchar_t *pageToken = 0;
    bool bContinueLoop = rest.get_LastMethodSuccess() && (rest.get_ResponseStatusCode() == 200);

    while (bContinueLoop == true) {

        wprintf(L"---- Page %d ----\n",pageNumber);
        json.Load(jsonResponse);

        numFiles = json.SizeOfArray(L"files");
        i = 0;
        while (i < numFiles) {
            // Add this file ID to the master list.
            json.put_I(i);
            jsonMasterArr->AddStringAt(-1,json.stringOf(L"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(L"nextPageToken");
        bContinueLoop = false;
        bool bHasMorePages = json.get_LastMethodSuccess();
        if (bHasMorePages == true) {
            rest.ClearAllQueryParams();
            rest.AddQueryParam(L"pageSize",L"200");
            rest.AddQueryParam(L"pageToken",pageToken);
            jsonResponse = rest.fullRequestNoBody(L"GET",L"/drive/v3/files");
            bContinueLoop = rest.get_LastMethodSuccess() && (rest.get_ResponseStatusCode() == 200);
            pageNumber = pageNumber + 1;
        }

    }

    delete jsonMasterArr;

    // Check to see if the above loop exited with errors...
    if (rest.get_LastMethodSuccess() != true) {
        wprintf(L"%s\n",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.get_ResponseStatusCode() != 200) {
        wprintf(L"response status code = %d\n",rest.get_ResponseStatusCode());
        wprintf(L"response status text = %s\n",rest.responseStatusText());
        wprintf(L"response header: %s\n",rest.responseHeader());
        wprintf(L"response JSON: %s\n",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.)
    CkHashtableW hashTable;
    // Set the capacity of the hash table to something reasonable for the number of files
    // to be hashed.
    hashTable.ClearWithNewCapacity(521);

    CkStringBuilderW sbPathForFileId;

    // Used for storing the file name and parents[0] in the hashTable.
    CkStringArrayW saFileInfo;
    saFileInfo.put_Unique(false);

    const wchar_t *fileId = 0;
    numFiles = jsonMaster.SizeOfArray(L"fileIds");
    i = 0;
    while (i < numFiles) {
        jsonMaster.put_I(i);
        fileId = jsonMaster.stringOf(L"fileIds[i]");
        sbPathForFileId.SetString(L"/drive/v3/files/");
        sbPathForFileId.Append(fileId);

        rest.ClearAllQueryParams();
        rest.AddQueryParam(L"fields",allFields);
        jsonResponse = rest.fullRequestNoBody(L"GET",sbPathForFileId.getAsString());
        if ((rest.get_LastMethodSuccess() != true) || (rest.get_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,L"",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(L"name"));
        saFileInfo.Append(json.stringOf(L"parents[0]"));
        hashTable.AddStr(fileId,saFileInfo.serialize());

        wprintf(L"%s, %s\n",json.stringOf(L"name"),json.stringOf(L"parents[0]"));

        i = i + 1;
    }

    // Check to see if the above loop exited with errors...
    if (rest.get_LastMethodSuccess() != true) {
        wprintf(L"%s\n",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.get_ResponseStatusCode() != 200) {
        wprintf(L"response status code = %d\n",rest.get_ResponseStatusCode());
        wprintf(L"response status text = %s\n",rest.responseStatusText());
        wprintf(L"response header: %s\n",rest.responseHeader());
        wprintf(L"response JSON: %s\n",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"
    // 

    wprintf(L"---- building paths ----\n");

    CkStringBuilderW sbPath;
    numFiles = jsonMaster.SizeOfArray(L"fileIds");
    i = 0;
    while (i < numFiles) {
        jsonMaster.put_I(i);

        sbPath.Clear();

        fileId = jsonMaster.stringOf(L"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(L"/");
            }

        }

        wprintf(L"%d: %s\n",i,sbPath.getAsString());

        // Store the filePath --> fileId mapping in our local cache.
        fileId = jsonMaster.stringOf(L"fileIds[i]");
        gdCache.SaveTextDt(sbPath.getAsString(),dtExpire,L"",fileId);

        jsonMasterPaths->AddStringAt(-1,sbPath.getAsString());

        i = i + 1;
    }

    delete jsonMasterPaths;

    // Save the master list of file IDs and file paths to the local cache.
    jsonMaster.put_EmitCompact(false);
    const wchar_t *strJsonMaster = jsonMaster.emit();
    gdCache.SaveTextNoExpire(L"AllGoogleDriveFileIds",L"",strJsonMaster);
    wprintf(L"JSON Master Record:\n");
    wprintf(L"%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",
    //   ]
    // }

    wprintf(L"Entire cache rebuilt...\n");
    }