(SQL Server) Refresh GMail SMTP OAuth2 Access Token

Demonstrates how to refresh an access token for sending email via GMail (SMTP).

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

-- Important: See this note about string length limitations for strings returned by sp_OAMethod calls.
--
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    -- Important: Do not use nvarchar(max).  See the warning about using nvarchar(max).
    DECLARE @sTmp0 nvarchar(4000)
    -- This example requires the Chilkat API to have been previously unlocked.
    -- See Global Unlock Sample for sample code.

    -- See Get GMail SMTP Access Token 
    -- for sample code showing how to obtain a GMail SMTP access token for desktop apps.

    -- It is assumed we previously obtained an OAuth2 access token for GMail (one with a scope for sending email).

    DECLARE @jsonToken int
    -- Use "Chilkat_9_5_0.JsonObject" for versions of Chilkat < 10.0.0
    EXEC @hr = sp_OACreate 'Chilkat.JsonObject', @jsonToken OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    DECLARE @success int
    EXEC sp_OAMethod @jsonToken, 'LoadFile', @success OUT, 'qa_data/tokens/_gmailSmtp.json'
    IF @success <> 1
      BEGIN

        PRINT 'Failed to load _gmailSmtp.json'
        EXEC @hr = sp_OADestroy @jsonToken
        RETURN
      END

    -- The access token JSON looks something like this:

    -- 	{ 
    -- 	 "access_token": "abac.Ci-ZabcdF37-NUrmSzxbHxTsMbtlN-uPfabcdAQN_2ekzj0s5ofCzRabcdTDMGaa2Q",
    -- 	 "token_type": "Bearer",
    -- 	 "expires_in": 3600,
    -- 	 "refresh_token": "1/lEe5abcdNJ77eOSDBabcdkQGVmDalkwabcdR2Hatbo"
    -- 	}
    -- 

    DECLARE @oauth2 int
    -- Use "Chilkat_9_5_0.OAuth2" for versions of Chilkat < 10.0.0
    EXEC @hr = sp_OACreate 'Chilkat.OAuth2', @oauth2 OUT

    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'

    -- Get the "refresh_token"
    EXEC sp_OAMethod @jsonToken, 'StringOf', @sTmp0 OUT, 'refresh_token'
    EXEC sp_OASetProperty @oauth2, 'RefreshToken', @sTmp0

    -- Send the HTTP POST to refresh the access token..
    EXEC sp_OAMethod @oauth2, 'RefreshAccessToken', @success OUT
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @oauth2, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @jsonToken
        EXEC @hr = sp_OADestroy @oauth2
        RETURN
      END

    -- The response contains a new access token, but we must keep
    -- our existing refresh token for when we need to refresh again in the future.
    EXEC sp_OAGetProperty @oauth2, 'AccessToken', @sTmp0 OUT
    EXEC sp_OAMethod @jsonToken, 'UpdateString', @success OUT, 'access_token', @sTmp0

    -- Save the new JSON access token response to a file.
    DECLARE @sbJson int
    -- Use "Chilkat_9_5_0.StringBuilder" for versions of Chilkat < 10.0.0
    EXEC @hr = sp_OACreate 'Chilkat.StringBuilder', @sbJson OUT

    EXEC sp_OASetProperty @jsonToken, 'EmitCompact', 0
    EXEC sp_OAMethod @jsonToken, 'EmitSb', @success OUT, @sbJson
    EXEC sp_OAMethod @sbJson, 'WriteFile', @success OUT, 'qa_data/tokens/_gmailSmtp.json', 'utf-8', 0


    PRINT 'OAuth2 authorization granted!'

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

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


END
GO