(C++) PayPal Generate QR Code

Generates a QR code for an invoice, by ID.

The QR code is a PNG image in Base64-encoded format that corresponds to the invoice ID.

Note: A QR code can only be generated for an invoice that has been both created and sent.

See also Generate QR Code

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#include <CkJsonObject.h>
#include <CkStringBuilder.h>
#include <CkRest.h>
#include <CkBinData.h>

void ChilkatSample(void)
    {
    // Note: Requires Chilkat v9.5.0.64 or greater.

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

    // Load our previously obtained access token. (see PayPal OAuth2 Access Token)
    CkJsonObject jsonToken;
    jsonToken.LoadFile("qa_data/tokens/paypal.json");

    // Build the Authorization request header field value.
    CkStringBuilder sbAuth;
    // token_type should be "Bearer"
    sbAuth.Append(jsonToken.stringOf("token_type"));
    sbAuth.Append(" ");
    sbAuth.Append(jsonToken.stringOf("access_token"));

    // Make the initial connection.
    // A single REST object, once connected, can be used for many PayPal REST API calls.
    // The auto-reconnect indicates that if the already-established HTTPS connection is closed,
    // then it will be automatically re-established as needed.
    CkRest rest;
    bool bAutoReconnect = true;
    bool success = rest.Connect("api.sandbox.paypal.com",443,true,bAutoReconnect);
    if (success != true) {
        std::cout << rest.lastErrorText() << "\r\n";
        return;
    }

    // ----------------------------------------------------------------------------------------------
    // The code above this comment could be placed inside a function/subroutine within the application
    // because the connection does not need to be made for every request.  Once the connection is made
    // the app may send many requests..
    // ----------------------------------------------------------------------------------------------

    // Build a path using an invoice ID.
    CkStringBuilder sbPath;
    sbPath.Append("/v1/invoicing/invoices/invoice_id/qr-code");
    int numReplacements = sbPath.Replace("invoice_id","INV2-ZG2H-HKAW-PMWU-N6ZR");

    rest.AddHeader("Authorization",sbAuth.getAsString());
    // A 500x500 image results in a PNG file of approx. 4K bytes in size.
    rest.AddQueryParam("width","500");
    rest.AddQueryParam("height","500");
    rest.AddQueryParam("action","pay");

    // Send the GET request and get the PNG image data as base64.
    // A successful JSON response looks like this:
    // {"image":"iVBORw0KGgoAA....AASUVORK5CYII="}
    CkStringBuilder sbJsonResponse;
    success = rest.FullRequestNoBodySb("GET",sbPath.getAsString(),sbJsonResponse);
    if (success != true) {
        std::cout << rest.lastErrorText() << "\r\n";
        return;
    }

    CkJsonObject json;
    json.put_EmitCompact(false);
    json.LoadSb(sbJsonResponse);

    std::cout << "Response Status Code = " << rest.get_ResponseStatusCode() << "\r\n";

    // Did we get a 200 success response?
    if (rest.get_ResponseStatusCode() != 200) {
        std::cout << json.emit() << "\r\n";
        std::cout << "Failed." << "\r\n";
        return;
    }

    // If the 200 response is received, the response body contains the PNG data.
    // Save the PNG to a file.
    CkBinData pngData;
    pngData.AppendEncoded(json.stringOf("image"),"base64");
    success = pngData.WriteFile("qa_output/paypal_qr_code.png");
    if (success == false) {
        std::cout << "Failed to save PNG file." << "\r\n";
        return;
    }

    std::cout << "Success." << "\r\n";
    }