Xojo Plugin Requires Chilkat v10.1.2+

HMRC OAuth2 Access Token

See more OAuth2 Examples

Demonstrates how to get an HMRC OAuth2 access token from a desktop (installed) application or script. This example gets an HMRC MTD VAT read/write access token. Xojo Plugin

Dim success As Boolean
success = False

//  To further clarify, see OAuth 2.0 Authorization Flow

Dim oauth2 As New Chilkat.OAuth2

//  This should be the port in the localhost callback URL for your app.
//  Important: Make sure the callback URI in your HMRC developer app 
//  is exactly "http://localhost:3017/".  Don't forget the ending "/" char.
//  The callback URL would look like "http://localhost:3017/" if the port number is 3017.

//  IMPORTANT: Don't forget to setup your HMRC application to use the Redirect URI "http://localhost:3017/" as shown
//  here: Configure Redirect URI for HMRC application
oauth2.ListenPort = 3017

oauth2.AuthorizationEndpoint = "https://test-api.service.hmrc.gov.uk/oauth/authorize"
oauth2.TokenEndpoint = "https://test-api.service.hmrc.gov.uk/oauth/token"

//  Replace with your actual client ID
oauth2.ClientId = "HMRC-CLIENT-ID"

//  The scopes are documented in the HMRC reference documentation for each API.
//  This example gets a read/write access token for the HMRC MTD VAT API.
oauth2.Scope = "read:vat write:vat"

//  Begin the OAuth2 Authorization code flow.  This returns a URL that should be loaded in a browser.
Dim url As String
url = oauth2.StartAuth()
If (oauth2.LastMethodSuccess <> True) Then
    System.DebugLog(oauth2.LastErrorText)
    Return
End If

//  Launch the default browser on the system and navigate to the url.
//  The LaunchBrowser method was added in Chilkat v10.1.2.
success = oauth2.LaunchBrowser(url)
If (success = False) Then
    System.DebugLog(oauth2.LastErrorText)
    Return
End If

//  Wait for the user to approve or deny authorization in the browser.
Dim numMsWaited As Int32
numMsWaited = 0
While (numMsWaited < 90000) And (oauth2.AuthFlowState < 3)
    oauth2.SleepMs 100
    numMsWaited = numMsWaited + 100
Wend

//  If the browser does not respond within the specified time, AuthFlowState will be:
//  
//  1: Waiting for Redirect – The OAuth2 background thread is waiting for the browser's redirect request.
//  2: Waiting for Final Response – The thread is awaiting the final access token response.
//  In either case, cancel the background task initiated by StartAuth.

If (oauth2.AuthFlowState < 3) Then
    success = oauth2.Cancel()
    System.DebugLog("No response from the browser!")
    Return
End If

//  Check AuthFlowState to determine if authorization was granted, denied, or failed:
//  
//  3: Success – OAuth2 flow completed, the background thread exited, and the successful response is in AccessTokenResponse.
//  4: Access Denied – OAuth2 flow completed, the background thread exited, and the error response is in AccessTokenResponse.
//  5: Failure – OAuth2 flow failed before completion, the background thread exited, and error details are in FailureInfo.

If (oauth2.AuthFlowState = 5) Then
    System.DebugLog("OAuth2 failed to complete.")
    System.DebugLog(oauth2.FailureInfo)
    Return
End If

If (oauth2.AuthFlowState = 4) Then
    System.DebugLog("OAuth2 authorization was denied.")
    System.DebugLog(oauth2.AccessTokenResponse)
    Return
End If

If (oauth2.AuthFlowState <> 3) Then
    System.DebugLog("Unexpected AuthFlowState:" + Str(oauth2.AuthFlowState))
    Return
End If

System.DebugLog("OAuth2 authorization granted!")
System.DebugLog("Access Token = " + oauth2.AccessToken)

//  Get the full JSON response:
Dim json As New Chilkat.JsonObject
success = json.Load(oauth2.AccessTokenResponse)
json.EmitCompact = False
System.DebugLog(json.Emit())

//  The JSON response looks like this:

//  {
//    "token_type": "Bearer",
//    "scope": "user_impersonation",
//    "expires_in": "3599",
//    "ext_expires_in": "0",
//    "expires_on": "1524783438",
//    "not_before": "1524779538",
//    "resource": "https://mydomain.api.crm.dynamics.com",
//    "access_token": "...",
//    "refresh_token": "...",
//    "id_token": "..."
//  }

//  If an "expires_on" member does not exist, then add the JSON member by
//  getting the current system date/time and adding the "expires_in" seconds.
//  This way we'll know when the token expires.
If (json.HasMember("expires_on") <> True) Then
    Dim dtExpire As New Chilkat.CkDateTime
    success = dtExpire.SetFromCurrentSystemTime()
    success = dtExpire.AddSeconds(json.IntOf("expires_in"))
    success = json.AppendString("expires_on",dtExpire.GetAsUnixTimeStr(False))
End If

System.DebugLog(json.Emit())

//  Save the JSON to a file for future requests.
Dim fac As New Chilkat.FileAccess
success = fac.WriteEntireTextFile("qa_data/tokens/hmrc.json",json.Emit(),"utf-8",False)