(PureBasic) Google Sheets Refresh an Expired Access Token

Demonstrates how to refresh an expired access token. If a Google Sheets REST API call results in a 401 "unauthorized" response, then it is likely the access token expired. An application should be able to automatically refresh the access token with no user interaction and then re-try the request with the newly obtained access token.

Chilkat PureBasic Module Download Chilkat PureBasic Module

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

Procedure ChilkatExample()

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

    ;  It is assumed we previously obtained an OAuth2 access token.
    ;  This example loads the JSON access token file
    ;  saved by this example: Get Google Sheets OAuth2 Access Token

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

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

    ;  The access token JSON looks 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/googleSheets.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