Visual FoxPro

Egyptian eReceipt OAuth2 Client Credentials

See more Egypt eReceipt Examples

Get an OAuth2 access token for the Egyptian eReceipt REST API using client credentials (no interactivity with a web browser required). Visual FoxPro

LOCAL lnSuccess
LOCAL loHttp
LOCAL loReq
LOCAL loResp
LOCAL loSbResponseBody
LOCAL loJResp
LOCAL lnRespStatusCode
LOCAL lcToken_type
LOCAL lcAccess_token
LOCAL lcExpires_in
LOCAL lcScope

lnSuccess = 0

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

loHttp = CreateObject('Chilkat.Http')

* Note: Any provider of a REST API, such as the Egyptian government in this case, can make life 
* much easier for developers by providing one or more of the following in the API documentation:
* 
* 1) A sample CURL statement for each API call.
* 2) A Postman collection, or Swagger/OpenAPI specification file.
* 3) A sample of a raw HTTP request and response for each API call.
* 
* The sample CURL statements or raw HTTP request/responses do not need to comprehensively show all 
* possible options.  Providing a sample allows one to quickly make a successful API call.
* It also allows for code generation directly from the CURL, Postman collection, or raw request/response,
* and it tends to answer all questions about the format/structure of a request that, suprisingly,
* remain ambiguous or not obvious in other forms of documentation.

loReq = CreateObject('Chilkat.HttpRequest')
loReq.AddParam("grant_type","client_credentials")
* Use your actual client ID and client secret...
loReq.AddParam("client_id","d0394a9f-0607-40de-a978-2d3eb8375b04")
loReq.AddParam("client_secret","6d62315e-d65a-4e41-9112-4195ea834edf")

loReq.AddHeader("posserial","1234567899")
loReq.AddHeader("pososversion","os")
loReq.AddHeader("posmodelframework","1")
loReq.AddHeader("presharedkey","03ac674216f3e1...")

* When writing this example, the documentation at https://sdk.invoicing.eta.gov.eg/ereceiptapi/01-authenticate-pos/
* shows us the HTTP verb and path (POST /connect/token), however,
* we don't see the actual domain where the request is to be sent.
* What are the endpoints???
* It took some searching, but we found some endpoints here:  https://sdk.invoicing.eta.gov.eg/faq/
* It's not immediately apparent which endpoint is to be used with a given API call.
* Why not just include the endpoint in the documentation for each REST API call?
* Endpoints are literally the #1 thing that needs to be known.
* They can't just be buried in a FAQ.  They should be up-front and obvious.
* 
* So.. we're guessing the endpoint is likely "https://invoicing.eta.gov.eg/connect/token"
loReq.HttpVerb = "POST"
loReq.ContentType = "application/x-www-form-urlencoded"

loResp = CreateObject('Chilkat.HttpResponse')
lnSuccess = loHttp.HttpReq("https://invoicing.eta.gov.eg/connect/token",loReq,loResp)
IF (lnSuccess = 0) THEN
    ? loHttp.LastErrorText
    RELEASE loHttp
    RELEASE loReq
    RELEASE loResp
    CANCEL
ENDIF

loSbResponseBody = CreateObject('Chilkat.StringBuilder')
loResp.GetBodySb(loSbResponseBody)

loJResp = CreateObject('Chilkat.JsonObject')
loJResp.LoadSb(loSbResponseBody)
loJResp.EmitCompact = 0

? "Response Body:"
? loJResp.Emit()

lnRespStatusCode = loResp.StatusCode
? "Response Status Code = " + STR(lnRespStatusCode)
IF (lnRespStatusCode >= 400) THEN
    ? "Response Header:"
    ? loResp.Header
    ? "Failed."
    RELEASE loHttp
    RELEASE loReq
    RELEASE loResp
    RELEASE loSbResponseBody
    RELEASE loJResp
    CANCEL
ENDIF

* If successful, the OAuth2 access token JSON looks like this:

* {
*   "token_type": "Bearer",
*   "access_token": "eyJraW......R2sbqrY",
*   "expires_in": "3600",
*   "scope": "..."
* }

lcToken_type = loJResp.StringOf("token_type")
lcAccess_token = loJResp.StringOf("access_token")
lcExpires_in = loJResp.StringOf("expires_in")
lcScope = loJResp.StringOf("scope")

RELEASE loHttp
RELEASE loReq
RELEASE loResp
RELEASE loSbResponseBody
RELEASE loJResp