(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_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 = 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 = CkJsonObject_AppendArray(jsonMaster,"fileIds");
    // Also keep a list of file paths.
    jsonMasterPaths = CkJsonObject_AppendArray(jsonMaster,"filePaths");

    // 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;
        }

    }

    CkJsonArray_Dispose(jsonMasterArr);

    // Check to see if the above loop exited with errors...
    if (CkRest_getLastMethodSuccess(rest) != TRUE) {
        printf("%s\n",CkRest_lastErrorText(rest));
        CkAuthGoogle_Dispose(gAuth);
        CkRest_Dispose(rest);
        CkCache_Dispose(gdCache);
        CkDateTime_Dispose(dtExpire);
        CkJsonObject_Dispose(jsonMaster);
        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);
        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) != TRUE) {
        printf("%s\n",CkRest_lastErrorText(rest));
        CkAuthGoogle_Dispose(gAuth);
        CkRest_Dispose(rest);
        CkCache_Dispose(gdCache);
        CkDateTime_Dispose(dtExpire);
        CkJsonObject_Dispose(jsonMaster);
        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);
        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;
    }

    CkJsonArray_Dispose(jsonMasterPaths);

    // 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);
    CkJsonObject_Dispose(json);
    CkHashtable_Dispose(hashTable);
    CkStringBuilder_Dispose(sbPathForFileId);
    CkStringArray_Dispose(saFileInfo);
    CkStringBuilder_Dispose(sbPath);

    }