(C++) Facebook Download all Photos to Local Files

Demonstrates how to download all of one's Facebook photos to a local filesystem directory. This sample code keeps a local cache to avoid re-downloading the same photos twice. The program can be run again after a time, and it will download only photos that haven't yet been downloaded.

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#include <CkCache.h>
#include <CkOAuth2.h>
#include <CkRest.h>
#include <CkJsonObject.h>
#include <CkStringArray.h>
#include <CkStringBuilder.h>
#include <CkHttp.h>
#include <CkByteData.h>
#include <CkFileAccess.h>

void ChilkatSample(void)
    {
    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // This example will use a local disk cache to avoid re-fetching the same
    // photo id after it's been fetched once.
    CkCache fbCache;
    // The cache will use 1 level of 256 sub-directories.
    fbCache.put_Level(1);
    // Use a directory path that makes sense on your operating system..
    fbCache.AddRoot("C:/fbCache");

    // This example assumes a previously obtained an access token
    CkOAuth2 oauth2;
    oauth2.put_AccessToken("FACEBOOK-ACCESS-TOKEN");

    CkRest rest;

    // Connect to Facebook.
    bool success = rest.Connect("graph.facebook.com",443,true,true);
    if (success != true) {
        std::cout << rest.lastErrorText() << "\r\n";
        return;
    }

    // Provide the authentication credentials (i.e. the access key)
    rest.SetAuthOAuth2(oauth2);

    // There are two choices:  
    // We can choose to download the photos the person is tagged in or has uploaded
    // by setting type to "tagged" or "uploaded".
    rest.AddQueryParam("type","uploaded");

    // To download all photos, we begin with an outer loop that iterates over
    // the list of photo nodes in pages.  Each page returned contains a list of 
    // photo node ids.  Each photo node id must be retrieved to get the download URL(s)
    // of the actual image.

    // I don't know the max limit for the number of records that can be downloaded at once.
    rest.AddQueryParam("limit","100");

    // Get the 1st page of photos ids.
    // See https://developers.facebook.com/docs/graph-api/reference/user/photos/ for more information.
    const char *responseJson = rest.fullRequestNoBody("GET","/v2.7/me/photos");
    if (rest.get_LastMethodSuccess() != true) {
        std::cout << rest.lastErrorText() << "\r\n";
        return;
    }

    CkJsonObject photoJson;
    CkStringArray saPhotoUrls;
    CkStringBuilder sbPhotoIdPath;

    CkJsonObject json;
    json.put_EmitCompact(false);
    json.Load(responseJson);

    int i;
    const char *photoId = 0;
    const char *imageUrl = 0;

    // Get the "after" cursor.
    const char *afterCursor = json.stringOf("paging.cursors.after");
    while (json.get_LastMethodSuccess() == true) {

        std::cout << "-------------------" << "\r\n";
        std::cout << "afterCursor = " << afterCursor << "\r\n";

        // For each photo id in this page...
        i = 0;
        int numItems = json.SizeOfArray("data");
        while (i < numItems) {
            json.put_I(i);
            photoId = json.stringOf("data[i].id");
            std::cout << "photoId = " << photoId << "\r\n";

            // We need to fetch the JSON for this photo.  Check to see if it's in the local disk cache,
            // and if not, then get it from Facebook.
            const char *photoJsonStr = fbCache.fetchText(photoId);
            if (fbCache.get_LastMethodSuccess() == false) {
                // It's not locally available, so get it from Facebook..
                sbPhotoIdPath.Clear();
                sbPhotoIdPath.Append("/v2.7/");
                sbPhotoIdPath.Append(photoId);

                rest.ClearAllQueryParams();
                rest.AddQueryParam("fields","id,album,images");

                std::cout << "Fetching photo node from Facebook..." << "\r\n";

                // This REST request will continue using the existing connection.
                // If the connection was closed, it will automatically reconnect to send the request.
                photoJsonStr = rest.fullRequestNoBody("GET",sbPhotoIdPath.getAsString());
                if (rest.get_LastMethodSuccess() != true) {
                    std::cout << rest.lastErrorText() << "\r\n";
                    return;
                }

                // Add the photo JSON to the local cache.
                fbCache.SaveTextNoExpire(photoId,"",photoJsonStr);
            }

            // Parse the photo JSON and add the main photo download URL to saPhotoUrls
            // There may be multiple URLs in the images array, but the 1st one is the largest and main photo URL.
            // The others are smaller sizes of the same photo.
            photoJson.Load(photoJsonStr);
            imageUrl = photoJson.stringOf("images[0].source");
            if (photoJson.get_LastMethodSuccess() == true) {

                // Actually, we'll add a small JSON document that contains both the image ID and the URL.
                CkJsonObject imgUrlJson;
                imgUrlJson.AppendString("id",photoId);
                imgUrlJson.AppendString("url",imageUrl);
                saPhotoUrls.Append(imgUrlJson.emit());
                std::cout << "imageUrl = " << imageUrl << "\r\n";
            }

            i = i + 1;
        }

        // Prepare for getting the next page of photos ids.
        // We can continue using the same REST object.
        // If already connected, we'll continue using the existing connection.
        // Otherwise, a new connection will automatically be made if needed.
        rest.ClearAllQueryParams();
        rest.AddQueryParam("type","uploaded");
        rest.AddQueryParam("limit","20");
        rest.AddQueryParam("after",afterCursor);

        // Get the next page of photo ids.
        responseJson = rest.fullRequestNoBody("GET","/v2.7/me/photos");
        if (rest.get_LastMethodSuccess() != true) {
            std::cout << rest.lastErrorText() << "\r\n";
            return;
        }

        json.Load(responseJson);
        afterCursor = json.stringOf("paging.cursors.after");
    }

    std::cout << "No more pages of photos." << "\r\n";

    // Now iterate over the photo URLs and download each to a file.
    // We can use Chilkat HTTP.  No Facebook authorization (access token) is required to download
    // the photo once the URL is known.  
    CkHttp http;

    // We'll cache the image data so that if run again, we don't re-download the same image again.
    int numUrls = saPhotoUrls.get_Count();
    i = 0;
    CkJsonObject urlJson;
    CkByteData imageBytes;
    CkFileAccess fac;

    while (i < numUrls) {
        urlJson.Load(saPhotoUrls.getString(i));
        photoId = urlJson.stringOf("id");
        imageUrl = urlJson.stringOf("url");

        // Check the local cache for the image data.
        // Only download and save if not already cached.
        success = fbCache.FetchFromCache(imageUrl,imageBytes);
        if (fbCache.get_LastMethodSuccess() == false) {
            //  This photo needs to be downloaded.

            CkStringBuilder sbImageUrl;
            sbImageUrl.Append(imageUrl);

            // Let's form a filename..
            const char *extension = ".jpg";
            if (sbImageUrl.Contains(".gif",false) == true) {
                extension = ".gif";
            }

            if (sbImageUrl.Contains(".png",false) == true) {
                extension = ".png";
            }

            if (sbImageUrl.Contains(".tiff",false) == true) {
                extension = ".tiff";
            }

            if (sbImageUrl.Contains(".bmp",false) == true) {
                extension = ".bmp";
            }

            CkStringBuilder sbLocalFilePath;
            sbLocalFilePath.Append("C:/Photos/facebook/uploaded/");
            sbLocalFilePath.Append(photoId);
            sbLocalFilePath.Append(extension);

            success = http.QuickGet(imageUrl,imageBytes);
            if (http.get_LastMethodSuccess() != true) {
                std::cout << http.lastErrorText() << "\r\n";
                return;
            }

            // We've downloaded the photo image bytes into memory.
            // Save it to the cache AND save it to the output file.
            fbCache.SaveToCacheNoExpire(imageUrl,"",imageBytes);
            fac.WriteEntireFile(sbLocalFilePath.getAsString(),imageBytes);

            std::cout << "Downloaded to " << sbLocalFilePath.getAsString() << "\r\n";
        }

        i = i + 1;
    }

    std::cout << "Finished downloading all Facebook photos!" << "\r\n";
    }