B4X
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.
Chilkat B4X Downloads

B4X
Dim success As Boolean = False

'  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)
Dim jsonToken As ChilkatJsonObject
jsonToken.Initialize
jsonToken.LoadFile("qa_data/tokens/paypal.json")

'  Build the Authorization request header field value.
Dim sbAuth As ChilkatStringBuilder
sbAuth.Initialize
'  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.
Dim rest As ChilkatRest
rest.Initialize("rest")
Dim bAutoReconnect As Boolean = True
success = rest.Connect("api.sandbox.paypal.com", 443, True, bAutoReconnect)
If success <> True Then
    Log(rest.LastErrorText)
    Return
End If


'  ----------------------------------------------------------------------------------------------
'  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.
Dim sbPath As ChilkatStringBuilder
sbPath.Initialize
sbPath.Append("/v1/invoicing/invoices/invoice_id/qr-code")
Dim numReplacements As Int = 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="}
Dim sbJsonResponse As ChilkatStringBuilder
sbJsonResponse.Initialize
success = rest.FullRequestNoBodySb("GET", sbPath.GetAsString, sbJsonResponse)
If success <> True Then
    Log(rest.LastErrorText)
    Return
End If


Dim json As ChilkatJsonObject
json.Initialize
json.EmitCompact = False
json.LoadSb(sbJsonResponse)

Log("Response Status Code = " & rest.ResponseStatusCode)

'  Did we get a 200 success response?
If rest.ResponseStatusCode <> 200 Then
    Log(json.Emit)
    Log("Failed.")
    Return
End If


'  If the 200 response is received, the response body contains the PNG data.
'  Save the PNG to a file.
Dim pngData As ChilkatBinData
pngData.Initialize
pngData.AppendEncoded(json.StringOf("image"), "base64")
success = pngData.WriteFile("qa_output/paypal_qr_code.png")
If success = False Then
    Log("Failed to save PNG file.")
    Return
End If


Log("Success.")