(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 <C_CkAuthGoogleW.h>
#include <C_CkRestW.h>
#include <C_CkCacheW.h>
#include <C_CkDateTimeW.h>
#include <C_CkJsonObjectW.h>
#include <C_CkJsonArrayW.h>
#include <C_CkHashtableW.h>
#include <C_CkStringBuilderW.h>
#include <C_CkStringArrayW.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkAuthGoogleW gAuth;
    HCkRestW rest;
    BOOL bAutoReconnect;
    HCkCacheW gdCache;
    int numCacheFilesDeleted;
    HCkDateTimeW dtExpire;
    const wchar_t *allFields;
    HCkJsonObjectW jsonMaster;
    HCkJsonArrayW jsonMasterArr;
    HCkJsonArrayW jsonMasterPaths;
    HCkJsonObjectW json;
    HCkJsonObjectW jsonFileMetadata;
    int i;
    int numFiles;
    const wchar_t *jsonResponse;
    int pageNumber;
    const wchar_t *pageToken;
    BOOL bContinueLoop;
    BOOL bHasMorePages;
    HCkHashtableW hashTable;
    HCkStringBuilderW sbPathForFileId;
    HCkStringArrayW saFileInfo;
    const wchar_t *fileId;
    HCkStringBuilderW sbPath;
    BOOL bFinished;
    const wchar_t *strJsonMaster;

    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 = CkAuthGoogleW_Create();
    CkAuthGoogleW_putAccessToken(gAuth,L"GOOGLE_DRIVE_ACCESS_TOKEN");

    rest = CkRestW_Create();

    // Connect using TLS.
    bAutoReconnect = TRUE;
    success = CkRestW_Connect(rest,L"www.googleapis.com",443,TRUE,bAutoReconnect);

    // Provide the authentication credentials (i.e. the access token)
    CkRestW_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 = CkCacheW_Create();
    CkCacheW_putLevel(gdCache,0);
    // Use a root directory that makes sense on your operating system..
    CkCacheW_AddRoot(gdCache,L"C:/ckCache/googleDrive");

    // If we are re-building the cache, we can first delete the entire contents of the cache.
    numCacheFilesDeleted = CkCacheW_DeleteAll(gdCache);

    // Create a date/time object with an time 7 days from the current date/time.
    dtExpire = CkDateTimeW_Create();
    CkDateTimeW_SetFromCurrentSystemTime(dtExpire);
    CkDateTimeW_AddDays(dtExpire,7);

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

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

    json = CkJsonObjectW_Create();

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

    pageNumber = 1;

    bContinueLoop = CkRestW_getLastMethodSuccess(rest) && (CkRestW_getResponseStatusCode(rest) == 200);

    while (bContinueLoop == TRUE) {

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

        numFiles = CkJsonObjectW_SizeOfArray(json,L"files");
        i = 0;
        while (i < numFiles) {
            // Add this file ID to the master list.
            CkJsonObjectW_putI(json,i);
            CkJsonArrayW_AddStringAt(jsonMasterArr,-1,CkJsonObjectW_stringOf(json,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 = CkJsonObjectW_stringOf(json,L"nextPageToken");
        bContinueLoop = FALSE;
        bHasMorePages = CkJsonObjectW_getLastMethodSuccess(json);
        if (bHasMorePages == TRUE) {
            CkRestW_ClearAllQueryParams(rest);
            CkRestW_AddQueryParam(rest,L"pageSize",L"200");
            CkRestW_AddQueryParam(rest,L"pageToken",pageToken);
            jsonResponse = CkRestW_fullRequestNoBody(rest,L"GET",L"/drive/v3/files");
            bContinueLoop = CkRestW_getLastMethodSuccess(rest) && (CkRestW_getResponseStatusCode(rest) == 200);
            pageNumber = pageNumber + 1;
        }

    }

    CkJsonArrayW_Dispose(jsonMasterArr);

    // Check to see if the above loop exited with errors...
    if (CkRestW_getLastMethodSuccess(rest) != TRUE) {
        wprintf(L"%s\n",CkRestW_lastErrorText(rest));
        CkAuthGoogleW_Dispose(gAuth);
        CkRestW_Dispose(rest);
        CkCacheW_Dispose(gdCache);
        CkDateTimeW_Dispose(dtExpire);
        CkJsonObjectW_Dispose(jsonMaster);
        CkJsonObjectW_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 (CkRestW_getResponseStatusCode(rest) != 200) {
        wprintf(L"response status code = %d\n",CkRestW_getResponseStatusCode(rest));
        wprintf(L"response status text = %s\n",CkRestW_responseStatusText(rest));
        wprintf(L"response header: %s\n",CkRestW_responseHeader(rest));
        wprintf(L"response JSON: %s\n",jsonResponse);
        CkAuthGoogleW_Dispose(gAuth);
        CkRestW_Dispose(rest);
        CkCacheW_Dispose(gdCache);
        CkDateTimeW_Dispose(dtExpire);
        CkJsonObjectW_Dispose(jsonMaster);
        CkJsonObjectW_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 = CkHashtableW_Create();
    // Set the capacity of the hash table to something reasonable for the number of files
    // to be hashed.
    CkHashtableW_ClearWithNewCapacity(hashTable,521);

    sbPathForFileId = CkStringBuilderW_Create();

    // Used for storing the file name and parents[0] in the hashTable.
    saFileInfo = CkStringArrayW_Create();
    CkStringArrayW_putUnique(saFileInfo,FALSE);

    numFiles = CkJsonObjectW_SizeOfArray(jsonMaster,L"fileIds");
    i = 0;
    while (i < numFiles) {
        CkJsonObjectW_putI(jsonMaster,i);
        fileId = CkJsonObjectW_stringOf(jsonMaster,L"fileIds[i]");
        CkStringBuilderW_SetString(sbPathForFileId,L"/drive/v3/files/");
        CkStringBuilderW_Append(sbPathForFileId,fileId);

        CkRestW_ClearAllQueryParams(rest);
        CkRestW_AddQueryParam(rest,L"fields",allFields);
        jsonResponse = CkRestW_fullRequestNoBody(rest,L"GET",CkStringBuilderW_getAsString(sbPathForFileId));
        if ((CkRestW_getLastMethodSuccess(rest) != TRUE) || (CkRestW_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.
        CkCacheW_SaveTextDt(gdCache,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..
        CkJsonObjectW_Load(json,jsonResponse);

        CkStringArrayW_Clear(saFileInfo);
        CkStringArrayW_Append(saFileInfo,CkJsonObjectW_stringOf(json,L"name"));
        CkStringArrayW_Append(saFileInfo,CkJsonObjectW_stringOf(json,L"parents[0]"));
        CkHashtableW_AddStr(hashTable,fileId,CkStringArrayW_serialize(saFileInfo));

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

        i = i + 1;
    }

    // Check to see if the above loop exited with errors...
    if (CkRestW_getLastMethodSuccess(rest) != TRUE) {
        wprintf(L"%s\n",CkRestW_lastErrorText(rest));
        CkAuthGoogleW_Dispose(gAuth);
        CkRestW_Dispose(rest);
        CkCacheW_Dispose(gdCache);
        CkDateTimeW_Dispose(dtExpire);
        CkJsonObjectW_Dispose(jsonMaster);
        CkJsonObjectW_Dispose(json);
        CkHashtableW_Dispose(hashTable);
        CkStringBuilderW_Dispose(sbPathForFileId);
        CkStringArrayW_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 (CkRestW_getResponseStatusCode(rest) != 200) {
        wprintf(L"response status code = %d\n",CkRestW_getResponseStatusCode(rest));
        wprintf(L"response status text = %s\n",CkRestW_responseStatusText(rest));
        wprintf(L"response header: %s\n",CkRestW_responseHeader(rest));
        wprintf(L"response JSON: %s\n",jsonResponse);
        CkAuthGoogleW_Dispose(gAuth);
        CkRestW_Dispose(rest);
        CkCacheW_Dispose(gdCache);
        CkDateTimeW_Dispose(dtExpire);
        CkJsonObjectW_Dispose(jsonMaster);
        CkJsonObjectW_Dispose(json);
        CkHashtableW_Dispose(hashTable);
        CkStringBuilderW_Dispose(sbPathForFileId);
        CkStringArrayW_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"
    // 

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

    sbPath = CkStringBuilderW_Create();
    numFiles = CkJsonObjectW_SizeOfArray(jsonMaster,L"fileIds");
    i = 0;
    while (i < numFiles) {
        CkJsonObjectW_putI(jsonMaster,i);

        CkStringBuilderW_Clear(sbPath);

        fileId = CkJsonObjectW_stringOf(jsonMaster,L"fileIds[i]");
        bFinished = FALSE;
        while ((bFinished == FALSE)) {
            CkStringArrayW_Clear(saFileInfo);
            CkStringArrayW_AppendSerialized(saFileInfo,CkHashtableW_lookupStr(hashTable,fileId));
            // Append this file or directory name.
            CkStringBuilderW_Prepend(sbPath,CkStringArrayW_getString(saFileInfo,0));
            // Get the parent fileId
            fileId = CkStringArrayW_getString(saFileInfo,1);
            // If this fileId is not in the hashtable, then it's the fileId for "My Drive", and we are finished.
            if (CkHashtableW_Contains(hashTable,fileId) == FALSE) {
                bFinished = TRUE;
            }
            else {
                CkStringBuilderW_Prepend(sbPath,L"/");
            }

        }

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

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

        CkJsonArrayW_AddStringAt(jsonMasterPaths,-1,CkStringBuilderW_getAsString(sbPath));

        i = i + 1;
    }

    CkJsonArrayW_Dispose(jsonMasterPaths);

    // Save the master list of file IDs and file paths to the local cache.
    CkJsonObjectW_putEmitCompact(jsonMaster,FALSE);
    strJsonMaster = CkJsonObjectW_emit(jsonMaster);
    CkCacheW_SaveTextNoExpire(gdCache,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");


    CkAuthGoogleW_Dispose(gAuth);
    CkRestW_Dispose(rest);
    CkCacheW_Dispose(gdCache);
    CkDateTimeW_Dispose(dtExpire);
    CkJsonObjectW_Dispose(jsonMaster);
    CkJsonObjectW_Dispose(json);
    CkHashtableW_Dispose(hashTable);
    CkStringBuilderW_Dispose(sbPathForFileId);
    CkStringArrayW_Dispose(saFileInfo);
    CkStringBuilderW_Dispose(sbPath);

    }