Xbase++

Square OAuth2 Access Token

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Demonstrates how to get an access token for the Square API. This example is for desktop apps only (not web apps). Xbase++

LOCAL nSuccess
LOCAL oOauth2
LOCAL cUrl
LOCAL oSbUrl
LOCAL nNumMsWaited
LOCAL oJson
LOCAL oFac

nSuccess := 0

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

oOauth2 := CreateObject("Chilkat.OAuth2")

//  This should be the port in the localhost callback URL for your app.  
//  The callback URL would look like "http://localhost:3017/" if the port number is 3017.
oOauth2:ListenPort := 3017

//  To use the production system, change the domains here to "connect.squareup.com"
oOauth2:AuthorizationEndpoint := "https://connect.squareupsandbox.com/oauth2/authorize"
oOauth2:TokenEndpoint := "https://connect.squareupsandbox.com/oauth2/token"

//  Replace these with actual values.
oOauth2:ClientId := "APPLICATION_ID"
oOauth2:ClientSecret := "APPLICATION_SECRET"

//  Make sure to include the scopes you'll need.
oOauth2:Scope := "ITEMS_WRITE ITEMS_READ"

//  Begin the OAuth2 three-legged flow.  This returns a URL that should be loaded in a browser.
cUrl := oOauth2:StartAuth()
IF (oOauth2:LastMethodSuccess == 0)
    ? oOauth2:LastErrorText
    oOauth2:destroy()
    RETURN
ENDIF

//  Add the session=False query param to the URL.
oSbUrl := CreateObject("Chilkat.StringBuilder")
oSbUrl:Append(cUrl)
oSbUrl:Append("&session=False")
//  Launch this URL in the browser.
cUrl := oSbUrl:GetAsString()

//  Launch the system's default browser navigated to the URL.
nSuccess := oOauth2:LaunchBrowser(cUrl)
IF (nSuccess == 0)
    ? oOauth2:LastErrorText
    oOauth2:destroy()
    oSbUrl:destroy()
    RETURN
ENDIF

//  Now wait for the authorization.
//  We'll wait for a max of 30 seconds.
nNumMsWaited := 0
DO WHILE (nNumMsWaited < 30000) .AND. (oOauth2:AuthFlowState < 3)
    oOauth2:SleepMs(100)
    nNumMsWaited := nNumMsWaited + 100
ENDDO

//  If there was no response from the browser within 30 seconds, then 
//  the AuthFlowState will be equal to 1 or 2.
//  1: Waiting for Redirect. The OAuth2 background thread is waiting to receive the redirect HTTP request from the browser.
//  2: Waiting for Final Response. The OAuth2 background thread is waiting for the final access token response.
//  In that case, cancel the background task started in the call to StartAuth.
IF (oOauth2:AuthFlowState < 3)
    oOauth2:Cancel()
    ? "No response from the browser!"
    oOauth2:destroy()
    oSbUrl:destroy()
    RETURN
ENDIF

//  Check the AuthFlowState to see if authorization was granted, denied, or if some error occurred
//  The possible AuthFlowState values are:
//  3: Completed with Success. The OAuth2 flow has completed, the background thread exited, and the successful JSON response is available in AccessTokenResponse property.
//  4: Completed with Access Denied. The OAuth2 flow has completed, the background thread exited, and the error JSON is available in AccessTokenResponse property.
//  5: Failed Prior to Completion. The OAuth2 flow failed to complete, the background thread exited, and the error information is available in the FailureInfo property.
IF (oOauth2:AuthFlowState == 5)
    ? "OAuth2 failed to complete."
    ? oOauth2:FailureInfo
    oOauth2:destroy()
    oSbUrl:destroy()
    RETURN
ENDIF

IF (oOauth2:AuthFlowState == 4)
    ? "OAuth2 authorization was denied."
    ? oOauth2:AccessTokenResponse
    oOauth2:destroy()
    oSbUrl:destroy()
    RETURN
ENDIF

IF (oOauth2:AuthFlowState != 3)
    ? "Unexpected AuthFlowState:" + Str(oOauth2:AuthFlowState)
    oOauth2:destroy()
    oSbUrl:destroy()
    RETURN
ENDIF

? "OAuth2 authorization granted!"
? "Access Token = " + oOauth2:AccessToken

//  Get the full JSON response:
oJson := CreateObject("Chilkat.JsonObject")
oJson:Load(oOauth2:AccessTokenResponse)
oJson:EmitCompact := 0

//  The JSON response looks like this:

//  {
//    "access_token": "EAAAE...depV",
//    "token_type": "bearer",
//    "expires_at": "2020-09-04T23:30:18Z",
//    "merchant_id": "MLQA83866KSR5",
//    "refresh_token": "EQAAEE...jeVfD6MV"
//  }

? oJson:Emit()

//  Save the JSON to a file for future requests.
oFac := CreateObject("Chilkat.FileAccess")
oFac:WriteEntireTextFile("qa_data/tokens/square.json", oJson:Emit(), "utf-8", 0)

oOauth2:destroy()
oSbUrl:destroy()
oJson:destroy()
oFac:destroy()