How to generate multiple Google Docs files using Java API

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1

I need to generate around 300 Google Docs files programmatically using Java. I tried implementing the Google Docs API but I keep running into permission issues. The error shows “Insufficient Permission” and “Request had insufficient authentication scopes” when trying to create documents. I think the problem might be with the scope configuration. Originally I had DOCUMENTS_READONLY scope but that didn’t work for creating files, so I changed it to DOCUMENTS scope but still getting the same 403 error. Here’s my implementation:

import com.google.api.client.auth.oauth2.Credential;
import com.google.api.client.extensions.java6.auth.oauth2.AuthorizationCodeInstalledApp;
import com.google.api.client.extensions.jetty.auth.oauth2.LocalServerReceiver;
import com.google.api.client.googleapis.auth.oauth2.GoogleAuthorizationCodeFlow;
import com.google.api.client.googleapis.auth.oauth2.GoogleClientSecrets;
import com.google.api.client.googleapis.javanet.GoogleNetHttpTransport;
import com.google.api.client.http.javanet.NetHttpTransport;
import com.google.api.client.json.JsonFactory;
import com.google.api.client.json.jackson2.JacksonFactory;
import com.google.api.client.util.store.FileDataStoreFactory;
import com.google.api.services.docs.v1.Docs;
import com.google.api.services.docs.v1.DocsScopes;
import com.google.api.services.docs.v1.model.Document;

public class DocumentGenerator {
    private static final String APP_NAME = "Document Creator Java App";
    private static final JsonFactory JSON_FACTORY = JacksonFactory.getDefaultInstance();
    private static final String TOKEN_DIR = "auth_tokens";
    private static final List<String> REQUIRED_SCOPES = Collections.singletonList(DocsScopes.DOCUMENTS);
    private static final String CREDS_FILE = "/client_credentials.json";
    
    private static Credential authorize(final NetHttpTransport transport) throws IOException {
        InputStream credStream = DocumentGenerator.class.getResourceAsStream(CREDS_FILE);
        GoogleClientSecrets secrets = GoogleClientSecrets.load(JSON_FACTORY, new InputStreamReader(credStream));
        
        GoogleAuthorizationCodeFlow authFlow = new GoogleAuthorizationCodeFlow.Builder(
                transport, JSON_FACTORY, secrets, REQUIRED_SCOPES)
                .setDataStoreFactory(new FileDataStoreFactory(new java.io.File(TOKEN_DIR)))
                .setAccessType("offline")
                .build();
        LocalServerReceiver receiver = new LocalServerReceiver.Builder().setPort(9999).build();
        return new AuthorizationCodeInstalledApp(authFlow, receiver).authorize("user");
    }
    
    private static void generateDocument(Docs docsService) throws IOException {
        Document newDoc = new Document().setTitle("Generated Document");
        newDoc = docsService.documents().create(newDoc).execute();
        System.out.println("Successfully created: " + newDoc.getTitle());
    }
}

Can someone help me figure out what’s wrong with the scope configuration or authentication setup?

2

also check your credentials.json file setup - sometimes it’s not the scopes but the OAuth client type. make sure you’re using ‘desktop application’ not ‘web application’ in google cloud console. try clearing your browser cache and redo the entire auth flow too.

3

Your scope configuration is accurate; DocsScopes.DOCUMENTS is indeed suitable for creating documents. However, the underlying issue stems from the fact that you are solely utilizing the Docs API, whereas you actually need both the Docs and Drive APIs to function together. The Docs API is responsible for managing document structure, while the Drive API handles file creation and permissions within Google Drive. It’s essential to include DriveScopes.DRIVE_FILE in your scope list and employ the Drive service to create the file initially, followed by the Docs service to update the content. I encountered this same issue last year when developing a similar batch document generator. Additionally, if you are not on a workspace account, ensure your OAuth consent screen is correctly configured for external users. The authentication flow sometimes retains outdated scopes, so it’s a good idea to delete your token directory and re-authenticate after adding the Drive scope.

4

This is probably a token caching issue, not wrong scopes. When you switched from DOCUMENTS_READONLY to DOCUMENTS, your old tokens are still sitting in TOKEN_DIR with the old permissions. Just delete the entire ‘auth_tokens’ directory and run your app again - it’ll force a fresh auth flow. I hit this exact same problem when I switched scopes in my document automation project. The cached credentials were causing all the trouble. Also, double-check that Google Docs API is actually enabled in your Google Cloud Console project, not just configured. Sometimes it shows up in your credentials but isn’t really activated. Your code looks fine otherwise, but I’d add some error handling around the auth flow to catch authentication exceptions.