PureBasic

Refresh GMail SMTP OAuth2 Access Token

See more OAuth2 Examples

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

IncludeFile "CkStringBuilder.pb"
IncludeFile "CkJsonObject.pb"
IncludeFile "CkOAuth2.pb"

Procedure ChilkatExample()

    success.i = 0

    ; 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).

    jsonToken.i = CkJsonObject::ckCreate()
    If jsonToken.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkJsonObject::ckLoadFile(jsonToken,"qa_data/tokens/_gmailSmtp.json")
    If success <> 1
        Debug "Failed to load _gmailSmtp.json"
        CkJsonObject::ckDispose(jsonToken)
        ProcedureReturn
    EndIf

    ; 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"
    ; 	}
    ; 

    oauth2.i = CkOAuth2::ckCreate()
    If oauth2.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkOAuth2::setCkTokenEndpoint(oauth2, "https://www.googleapis.com/oauth2/v4/token")

    ; Replace these with actual values.
    CkOAuth2::setCkClientId(oauth2, "GOOGLE-CLIENT-ID")
    CkOAuth2::setCkClientSecret(oauth2, "GOOGLE-CLIENT-SECRET")

    ; Get the "refresh_token"
    CkOAuth2::setCkRefreshToken(oauth2, CkJsonObject::ckStringOf(jsonToken,"refresh_token"))

    ; Send the HTTP POST to refresh the access token..
    success = CkOAuth2::ckRefreshAccessToken(oauth2)
    If success <> 1
        Debug CkOAuth2::ckLastErrorText(oauth2)
        CkJsonObject::ckDispose(jsonToken)
        CkOAuth2::ckDispose(oauth2)
        ProcedureReturn
    EndIf

    ; 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.
    CkJsonObject::ckUpdateString(jsonToken,"access_token",CkOAuth2::ckAccessToken(oauth2))

    ; Save the new JSON access token response to a file.
    sbJson.i = CkStringBuilder::ckCreate()
    If sbJson.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkJsonObject::setCkEmitCompact(jsonToken, 0)
    CkJsonObject::ckEmitSb(jsonToken,sbJson)
    CkStringBuilder::ckWriteFile(sbJson,"qa_data/tokens/_gmailSmtp.json","utf-8",0)

    Debug "OAuth2 authorization granted!"
    Debug "New Access Token = " + CkOAuth2::ckAccessToken(oauth2)


    CkJsonObject::ckDispose(jsonToken)
    CkOAuth2::ckDispose(oauth2)
    CkStringBuilder::ckDispose(sbJson)


    ProcedureReturn
EndProcedure