SQL Server

Get GMail OAuth2 Access Token for Desktop App

See more GMail REST API Examples

Demonstrates how to get a GMail OAuth2 access token from a desktop application or script.

This example requires a browser window to be displayed to allow the GMail account owner to authorize the access. The code for displaying the web browser is omitted. Suggestions for a few programming languages are provided in code comments. To complete this example, you will need to find out how to display a web browser and navigate to the URL returned by the call to oauth2.StartAuth.

SQL Server

-- Important: See this note about string length limitations for strings returned by sp_OAMethod calls.
--
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    DECLARE @iTmp0 int
    -- Important: Do not use nvarchar(max).  See the warning about using nvarchar(max).
    DECLARE @sTmp0 nvarchar(4000)
    DECLARE @success int
    SELECT @success = 0

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

    DECLARE @oauth2 int
    EXEC @hr = sp_OACreate 'Chilkat.OAuth2', @oauth2 OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    -- For Google OAuth2, set the listen port equal to the port used
    -- in the Authorized Redirect URL for the Client ID.
    -- For example, in this case the Authorized Redirect URL would be http://localhost:55568/
    -- Your app should choose a port not likely not used by any other application.
    EXEC sp_OASetProperty @oauth2, 'ListenPort', 55568

    EXEC sp_OASetProperty @oauth2, 'AuthorizationEndpoint', 'https://accounts.google.com/o/oauth2/v2/auth'
    EXEC sp_OASetProperty @oauth2, 'TokenEndpoint', 'https://www.googleapis.com/oauth2/v4/token'

    -- Replace these with actual values.
    EXEC sp_OASetProperty @oauth2, 'ClientId', 'GOOGLE-CLIENT-ID'
    EXEC sp_OASetProperty @oauth2, 'ClientSecret', 'GOOGLE-CLIENT-SECRET'

    EXEC sp_OASetProperty @oauth2, 'CodeChallenge', 1
    EXEC sp_OASetProperty @oauth2, 'CodeChallengeMethod', 'S256'

    -- See https://developers.google.com/gmail/api/auth/scopes for a list of GMail scopes.
    -- This is the full-permissions scope for GMail.
    EXEC sp_OASetProperty @oauth2, 'Scope', 'https://mail.google.com/'

    -- Important note about GMail scope for sending email:
    -- If the SMTP protocol is used for sending, then the full GMail scope is required: "https://mail.google.com/"
    -- Here is an example that sends GMail via the SMTP protocol:  Send GMail using SMTP
    -- If the GMail REST API is used, then the more restrictive Gmail scope can be used:  "https://www.googleapis.com/auth/gmail.send"
    -- Here is an example that sends GMail using the GMail REST API: Send GMail using REST API

    -- Begin the OAuth2 three-legged flow.  This returns a URL that should be loaded in a browser.
    DECLARE @url nvarchar(4000)
    EXEC sp_OAMethod @oauth2, 'StartAuth', @url OUT
    EXEC sp_OAGetProperty @oauth2, 'LastMethodSuccess', @iTmp0 OUT
    IF @iTmp0 = 0
      BEGIN
        EXEC sp_OAGetProperty @oauth2, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @oauth2
        RETURN
      END

    -- Launch the system's default browser navigated to the URL.
    EXEC sp_OAMethod @oauth2, 'LaunchBrowser', @success OUT, @url
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @oauth2, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @oauth2
        RETURN
      END

    -- Now wait for the authorization.
    -- We'll wait for a max of 30 seconds.
    DECLARE @numMsWaited int
    SELECT @numMsWaited = 0
    EXEC sp_OAGetProperty @oauth2, 'AuthFlowState', @iTmp0 OUT
    WHILE (@numMsWaited < 30000) and (@iTmp0 < 3)
      BEGIN
        EXEC sp_OAMethod @oauth2, 'SleepMs', NULL, 100
        SELECT @numMsWaited = @numMsWaited + 100
      END

    -- 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.
    EXEC sp_OAGetProperty @oauth2, 'AuthFlowState', @iTmp0 OUT
    IF @iTmp0 < 3
      BEGIN
        EXEC sp_OAMethod @oauth2, 'Cancel', @success OUT

        PRINT 'No response from the browser!'
        EXEC @hr = sp_OADestroy @oauth2
        RETURN
      END

    -- 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.
    EXEC sp_OAGetProperty @oauth2, 'AuthFlowState', @iTmp0 OUT
    IF @iTmp0 = 5
      BEGIN

        PRINT 'OAuth2 failed to complete.'
        EXEC sp_OAGetProperty @oauth2, 'FailureInfo', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @oauth2
        RETURN
      END

    EXEC sp_OAGetProperty @oauth2, 'AuthFlowState', @iTmp0 OUT
    IF @iTmp0 = 4
      BEGIN

        PRINT 'OAuth2 authorization was denied.'
        EXEC sp_OAGetProperty @oauth2, 'AccessTokenResponse', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @oauth2
        RETURN
      END

    EXEC sp_OAGetProperty @oauth2, 'AuthFlowState', @iTmp0 OUT
    IF @iTmp0 <> 3
      BEGIN

        EXEC sp_OAGetProperty @oauth2, 'AuthFlowState', @iTmp0 OUT
        PRINT 'Unexpected AuthFlowState:' + @iTmp0
        EXEC @hr = sp_OADestroy @oauth2
        RETURN
      END

    -- Save the full JSON access token response to a file.
    DECLARE @sbJson int
    EXEC @hr = sp_OACreate 'Chilkat.StringBuilder', @sbJson OUT

    EXEC sp_OAGetProperty @oauth2, 'AccessTokenResponse', @sTmp0 OUT
    EXEC sp_OAMethod @sbJson, 'Append', @success OUT, @sTmp0
    EXEC sp_OAMethod @sbJson, 'WriteFile', @success OUT, 'qa_data/tokens/gmail.json', 'utf-8', 0

    -- The saved JSON response looks like this:

    -- 	{
    -- 	 "access_token": "ya39.Ci-XA_C5bGgRDC3UaD-h0_NeL-DVIQnI2gHtBBBHkZzrwlARkwX6R3O0PCDEzRlfaQ",
    -- 	 "token_type": "Bearer",
    -- 	 "expires_in": 3600,
    -- 	 "refresh_token": "1/r_2c_7jddspcdfesrrfKqfXtqo08D6Q-gUU0DsdfVMsx0c"
    -- 	}
    -- 

    PRINT 'OAuth2 authorization granted!'

    EXEC sp_OAGetProperty @oauth2, 'AccessToken', @sTmp0 OUT
    PRINT 'Access Token = ' + @sTmp0

    EXEC @hr = sp_OADestroy @oauth2
    EXEC @hr = sp_OADestroy @sbJson


END
GO