(MFC) Download Photo to a File

Assuming we have the ID of a Photo, this example demonstrates how to download the photo image data to a file.

Chilkat C/C++ Library Downloads MS Visual C/C++ Libs

See Also: Using MFC CString in Chilkat

#include <CkOAuth2.h>
#include <CkRest.h>
#include <CkStringBuilder.h>
#include <CkJsonObject.h>
#include <CkHttp.h>

void ChilkatSample(void)
    {
    CkString strOut;

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

    // 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) {
        strOut.append(rest.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

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

    // Assumes we've already obtained a Photo ID.
    const char *photoId = "10210199026347451";

    CkStringBuilder sbPath;
    sbPath.Append("/v2.7/");
    sbPath.Append(photoId);

    // First we're going to get the photo informaton so we can get the URL of the image file data.
    // Select the fields we want.
    // See https://developers.facebook.com/docs/graph-api/reference/photo/
    rest.AddQueryParam("fields","id,album,images");

    const char *responseJson = rest.fullRequestNoBody("GET",sbPath.getAsString());
    if (rest.get_LastMethodSuccess() != true) {
        strOut.append(rest.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

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

    // Show the JSON in human-readable format.
    strOut.append(json.emit());
    strOut.append("\r\n");

    // Get the image URL.
    const char *imageUrl = json.stringOf("images[0].source");
    strOut.append("Downloading from ");
    strOut.append(imageUrl);
    strOut.append("\r\n");

    CkStringBuilder sbImageUrl;
    sbImageUrl.Append(imageUrl);

    // Build the output local file path.
    CkStringBuilder sbToPath;
    sbToPath.Append("qa_output/fb");
    sbToPath.Append(json.stringOf("id"));
    bool bCaseSensitive = false;
    if (sbImageUrl.Contains(".jpg",bCaseSensitive) == true) {
        sbToPath.Append(".jpg");
    }
    else {
        sbToPath.Append(".png");
    }

    strOut.append("Downloading to ");
    strOut.append(sbToPath.getAsString());
    strOut.append("\r\n");

    // Download using Chilkat HTTP.
    CkHttp http;
    success = http.Download(imageUrl,sbToPath.getAsString());
    if (success != true) {
        strOut.append(http.lastErrorText());
        strOut.append("\r\n");
    }
    else {
        strOut.append("Downloaded.");
        strOut.append("\r\n");
    }



    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }