(PureBasic) PayPal - Cancel Sent Invoice

Cancels a sent invoice, by ID, and, optionally, sends a notification about the cancellation to the payer, merchant, and Cc: emails.

Note: This example requires Chilkat v9.5.0.65 or greater.

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IncludeFile "CkStringBuilder.pb"
IncludeFile "CkJsonObject.pb"
IncludeFile "CkRest.pb"

Procedure ChilkatExample()

    ; Note: Requires Chilkat v9.5.0.65 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)
    jsonToken.i = CkJsonObject::ckCreate()
    If jsonToken.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkJsonObject::ckLoadFile(jsonToken,"qa_data/tokens/paypal.json")

    ; Build the Authorization request header field value.
    sbAuth.i = CkStringBuilder::ckCreate()
    If sbAuth.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; token_type should be "Bearer"
    CkStringBuilder::ckAppend(sbAuth,CkJsonObject::ckStringOf(jsonToken,"token_type"))
    CkStringBuilder::ckAppend(sbAuth," ")
    CkStringBuilder::ckAppend(sbAuth,CkJsonObject::ckStringOf(jsonToken,"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.
    rest.i = CkRest::ckCreate()
    If rest.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    bAutoReconnect.i = 1
    success.i = CkRest::ckConnect(rest,"api.sandbox.paypal.com",443,1,bAutoReconnect)
    If success <> 1
        Debug CkRest::ckLastErrorText(rest)
        CkJsonObject::ckDispose(jsonToken)
        CkStringBuilder::ckDispose(sbAuth)
        CkRest::ckDispose(rest)
        ProcedureReturn
    EndIf

    ; ----------------------------------------------------------------------------------------------
    ; 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 the JSON request body containing the reminder information:
    json.i = CkJsonObject::ckCreate()
    If json.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkJsonObject::setCkEmitCompact(json, 0)
    CkJsonObject::ckUpdateString(json,"subject","Past due")
    CkJsonObject::ckUpdateString(json,"note","Canceling invoice")
    CkJsonObject::ckUpdateBool(json,"send_to_merchant",1)
    CkJsonObject::ckUpdateBool(json,"send_to_payer",1)
    Debug CkJsonObject::ckEmit(json)

    ; The JSON created by the above code:

    ; 	{ 
    ; 	  "subject": "Past due",
    ; 	  "note": "Canceling invoice",
    ; 	  "send_to_merchant": true,
    ; 	  "send_to_payer": true
    ; 	}

    ; Build a path using a previously-sent invoice ID.
    sbPath.i = CkStringBuilder::ckCreate()
    If sbPath.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkStringBuilder::ckAppend(sbPath,"/v1/invoicing/invoices/invoice_id/cancel")
    numReplacements.i = CkStringBuilder::ckReplace(sbPath,"invoice_id","INV2-XPWZ-NUTQ-LNWB-P8NC")

    CkJsonObject::setCkEmitCompact(json, 1)
    sbRequestBody.i = CkStringBuilder::ckCreate()
    If sbRequestBody.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    sbResponseBody.i = CkStringBuilder::ckCreate()
    If sbResponseBody.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkRest::ckAddHeader(rest,"Content-Type","application/json")
    CkRest::ckAddHeader(rest,"Authorization",CkStringBuilder::ckGetAsString(sbAuth))
    CkJsonObject::ckEmitSb(json,sbRequestBody)

    success = CkRest::ckFullRequestSb(rest,"POST",CkStringBuilder::ckGetAsString(sbPath),sbRequestBody,sbResponseBody)
    If success <> 1
        Debug CkRest::ckLastErrorText(rest)
        CkJsonObject::ckDispose(jsonToken)
        CkStringBuilder::ckDispose(sbAuth)
        CkRest::ckDispose(rest)
        CkJsonObject::ckDispose(json)
        CkStringBuilder::ckDispose(sbPath)
        CkStringBuilder::ckDispose(sbRequestBody)
        CkStringBuilder::ckDispose(sbResponseBody)
        ProcedureReturn
    EndIf

    Debug "Response Status Code = " + Str(CkRest::ckResponseStatusCode(rest))

    ; In our testing, we received a 204 response, which is a success HTTP response code, but 
    ; differs from the PayPal REST API reference documentation, which states that a 202 response
    ; is expected.  I suspect an error in the PayPal documentation, or in the PayPal responder.
    ; Check for either 202 or 204..
    ; Did we get a 202 accepted response?
    If (CkRest::ckResponseStatusCode(rest) <> 202) AND (CkRest::ckResponseStatusCode(rest) <> 204)
        Debug CkStringBuilder::ckGetAsString(sbResponseBody)
        Debug "Failed."
        CkJsonObject::ckDispose(jsonToken)
        CkStringBuilder::ckDispose(sbAuth)
        CkRest::ckDispose(rest)
        CkJsonObject::ckDispose(json)
        CkStringBuilder::ckDispose(sbPath)
        CkStringBuilder::ckDispose(sbRequestBody)
        CkStringBuilder::ckDispose(sbResponseBody)
        ProcedureReturn
    EndIf

    ; The 202/204 response should be empty.  (Again, our experience differs from the online PayPal documentation..)
    Debug "Success."


    CkJsonObject::ckDispose(jsonToken)
    CkStringBuilder::ckDispose(sbAuth)
    CkRest::ckDispose(rest)
    CkJsonObject::ckDispose(json)
    CkStringBuilder::ckDispose(sbPath)
    CkStringBuilder::ckDispose(sbRequestBody)
    CkStringBuilder::ckDispose(sbResponseBody)


    ProcedureReturn
EndProcedure