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google-apps-scriptweb-applicationsoauthgoogle-oauthapp-inventor

Get and Use Access Tokens after user has authenticated with a google web app

I have developed a google apps script web app, in conjunction with an MIT App Inventor app, that will/should allow a user to access their own google drive/sheets/documents.

I am having trouble connecting to the web app through the Appinventor app's web component (not a webview), after the user had given their authorization to use the web app via their device's default browser (Chrome).

My Web App is connected to Google Cloud Console and has been verified by the Trust and Safety Team at Google. The app is set to "User who assesses the app" and "Anyone". I can't use the native webview in AppInventor, because Google blocked this off for authentication in 2016.

The web component offers GET/POST/PUT HTTP functions but I have no idea how to get the authorisation codes and tokens for a user in order to access the web app. (Note; the web app has no GUI, it simply receives GET requests and returns text/stringified json output for a range of functions.) I have been able to translate many curl examples in other situations to good effect with the web component, but not for 0Auth.

I have done my best to read up and use the offerings from Google on 0Auth, but just get lost halfway through, as always, nothing I do is quite the same as the examples or documentation provided.

How do I, therefore, construct HTTP GET URLs, with all the various authorization codes and tokens already in place, that will authorize the Web App to work for the user?

A simple request would be like this:

https://script.google.com/macros/s/AKfycbyZ_27nLOKi8ssX........Bz40yAbGfJt_TRswvm6zpY/exec?func=authenticate

which would return the text output "Authenticated"

With a web browser (Chrome) all of this is fairly straight forward for a user. If they are logged into their Google account in the browser they go to the URL provided for my web app, they will be asked to authenticate, and give my Web App access to their google account. Once accepted, 'magic' happens in the browser (any 'magic' happen at the web app end?), and as long as they stay logged in, they can use the browser to send GET requests (URLs with parameters) to the Web App and see the results returned in their browser. Happy days.

In my scenario, I do not have a suitable web browser capable of all of the above. I have a web component that can send GET/POST requests to web services, and handle the server responses. (think of it as a web 'terminal'). I can, therefore (hopefully) construct URLs with all the right content, codes, and parameters. Remember that this has to be straight forward for the user, who will not be interested in 'back end' activities, they will just want to use the app to do things on their google drive.

They need to, I guess, at the very least, perform the authentication in a web browser, to connect their Google account with the web app. Then with the web component connect to the web app using authorization codes and access tokens, as them (their google account) so that actions by the web app occur on their google drive. As stated above, the web app is set to "User who accesses the app" and "Anyone". This is the part I need help with. I do not understand what I need to do to connect the user to the web app without using a web browser.

This is the kind of thing I mean: https://developers.google.com/gdata/articles/using_cURL

Solution

  • Your setting of Web Apps and goal is as follows.

    • Web Apps is deployed as Who has access to the app: Anyone.
    • You want to make users access to Web Apps.

    Issue and solution:

    In the current situation, there are the following situations for using Web Apps.

    • When the users access to the Web Apps by each browser, the users can access by logging in to each Google account.
    • When you want to make users access to the methods (for example, curl command and script) except for the browser, it is required to share the Google Apps Script project of Web Apps with the users.

    Unfortunately, it seems that above situation is the current specification. I confirmed the change of this specification at April 11, 2018. Before this change, the users had been able to access to the Web Apps by the curl command and script with the access token without sharing the Google Apps Script project. By the change of specification, when the project is shared with the users, the users can access to Web Apps using the access token.

    In this case, it is required to include the access token to the request headers. Because in the current stage, access_token=### as the query parameters cannot be used. Ref

    Note:

    • From this situation, I think that when sharing the Google Apps Script project is not the direction you expect, in the current stage, the Web Apps with Who has access to the app: Anyone cannot be used by the method except for the browser.

    References: