B4X

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). B4X

Dim success As Boolean = False

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

Dim http As ChilkatHttp
http.Initialize("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.

Dim req As ChilkatHttpRequest
req.Initialize
req.AddParam("grant_type", "client_credentials")
'  Use your actual client ID and client secret...
req.AddParam("client_id", "d0394a9f-0607-40de-a978-2d3eb8375b04")
req.AddParam("client_secret", "6d62315e-d65a-4e41-9112-4195ea834edf")

req.AddHeader("posserial", "1234567899")
req.AddHeader("pososversion", "os")
req.AddHeader("posmodelframework", "1")
req.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"
req.HttpVerb = "POST"
req.ContentType = "application/x-www-form-urlencoded"

Dim resp As ChilkatHttpResponse
resp.Initialize
success = http.HttpReq("https://invoicing.eta.gov.eg/connect/token", req, resp)
If success = False Then
    Log(http.LastErrorText)
    Return
End If


Dim sbResponseBody As ChilkatStringBuilder
sbResponseBody.Initialize
resp.GetBodySb(sbResponseBody)

Dim jResp As ChilkatJsonObject
jResp.Initialize
jResp.LoadSb(sbResponseBody)
jResp.EmitCompact = False

Log("Response Body:")
Log(jResp.Emit)

Dim respStatusCode As Int = resp.StatusCode
Log("Response Status Code = " & respStatusCode)
If respStatusCode >= 400 Then
    Log("Response Header:")
    Log(resp.Header)
    Log("Failed.")
    Return
End If


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

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

Dim token_type As String = jResp.StringOf("token_type")
Dim access_token As String = jResp.StringOf("access_token")
Dim expires_in As String = jResp.StringOf("expires_in")
Dim scope As String = jResp.StringOf("scope")