Develop Reference

Authenticating user against app engine endpoints

I am creating my first app engine app and having problems with authenticating the users.
I have followed the https://cloud.google.com/appengine/docs/python/endpoints/consume_android#making_authenticated_calls - seems a bit magical, that I just "setAccountName" and it is supposed to work, but w/e, I guess that it should load the app scopes from Android Audience and then just check if the account name I passed has actually logged into the device.
The API call works, passes the authentication, but sadly - the "endpoints.get_current_user()" function on the backend returns None.
So I kept digging, but I can't seem to find anything on the topic. Best thing I have found is http://blog.notdot.net/2010/05/Authenticating-against-App-Engine-from-an-Android-app - but that's an article from 6 years ago and the author uses HTTP client and nothing related to endpoints libs.
All I can think of would be to follow some "non-endpoints" way of adding "login with Google" to my app and then try to pass the credentials I would get to my API builder, but that just feels wrong, like there should be an easier way to do that.
So, am I missing some step, that was not mentioned in https://cloud.google.com/appengine/docs/python/endpoints/consume_android#making_authenticated_calls ?
Actual code (slightly simplified) below:
Backend:
auth_api = endpoints.api(
name='auth_api',
version='v1.0',
auth_level=endpoints.AUTH_LEVEL.REQUIRED,
allowed_client_ids=[
ANDROID_CLIENT_ID,
WEB_CLIENT_ID,
endpoints.API_EXPLORER_CLIENT_ID,
],
audiences=[
WEB_CLIENT_ID,
endpoints.API_EXPLORER_CLIENT_ID,
],
scopes=[
'https://www.googleapis.com/auth/userinfo.profile',
'https://www.googleapis.com/auth/userinfo.email',
],
)
#auth_api.api_class(resource_name='rating')
class RatingHandler(remote.Service):
#endpoints.method(
message_types.VoidMessage,
RatingsMessage,
path='rating/getRatings',
http_method='GET',
)
def getRatings(self, request):
rating_query = Rating.query(
ancestor=ndb.Key(
Account,
endpoints.get_current_user().user_id(), // ERROR! endpoints.get_current_user() is None
)
).order(-Rating.rating)
Client:
// Somewhere these lines exist
if (credential == null || credential.getSelectedAccountName() == null) {
startActivityForResult(
AuthUtils.getCredentials(getActivity()).newChooseAccountIntent(),
AuthUtils.REQUEST_ACCOUNT_PICKER
);
} else {
LoadRatings();
}
#Override
public void onActivityResult(
int requestCode,
int resultCode,
Intent data
) {
super.onActivityResult(requestCode, resultCode, data);
if (data != null && data.getExtras() != null) {
String accountName =
data.getExtras().getString(
AccountManager.KEY_ACCOUNT_NAME
);
if (accountName != null) {
credential = GoogleAccountCredential.usingAudience(
getApplicationContext(),
"server:client_id:" + Constants.ANDROID_AUDIENCE
);
credential.setSelectedAccountName(accountName);
LoadRatings();
}
}
}
public void LoadRatings() {
// AuthApi was auto-generated by Google App Engine based on my Backend
AuthApi.Builder api = new AuthApi.Builder(
AndroidHttp.newCompatibleTransport(),
new AndroidJsonFactory(),
credential
).setApplicationName(getPackageName());
AuthApi service = api.build();
try {
ApiMessagesRatingRatedBeerListMessage result = service.rating().getRatings().
// some stuff done with result, but the Exception is thrown in line above

OK, I figured it out. When I removed "scopes" from API declaration, it works. I'm not sure how I am going to access user's email / profile yet, but that's at least a step forward.
This issue has been actually brought up before - How to add more scopes in GoogleCloud Endpoints - sadly, without any answers

You won't have a User object (Entity that is) on the backend created for you. You have to do that yourself. For example:
#Entity
public class AppEngineUser {
#Id
private String email;
private User user;
private AppEngineUser() {}
public AppEngineUser(User user) {
this.user = user;
this.email = user.getEmail();
}
public User getUser() {
return user;
}
public Key<AppEngineUser> getKey() {
return Key.create(AppEngineUser.class, email);
}
}
When you create an API method and specify a User object like this:
#ApiMethod(name = "insertRecord", path = "insert_record", httpMethod = HttpMethod.POST)
public Record insertRecord(User user, Record record)
// check if google user is authenticated
throws UnauthorizedException {
if (user == null) {
throw new UnauthorizedException("Authorization required");
}
// user is authenticated... do some stuff!
}
The User object is an injected type. It is actually: com.google.appengine.api.users.User. See "injected types" on https://cloud.google.com/appengine/docs/java/endpoints/paramreturn_types.
What this means is that GAE injects the Google user object if the user provided the correct credentials to their Google+ account. If they did not, then User will be null. If it is, you can throw an UnauthorizedException the way the above method does.
You can now get things like the User's gmail address among other things if the user object is not null. From there, you must store those values in your own custom entity, such as AppEngineUser and save it to the datastore. Then you can do other things with it later, such as load it, check if the user is registered and whatever else all by yourself.
Hope that helps!

Not fully listing Google Drive folders and files in Android app

I am trying to access all files and folders from google drive to a arraya list. But I can get only one file from Drive. What to do get all files and folders from google drive. I am using the following code..
Thanks
Arun
public void onConnected(Bundle connectionHint) {
// Log.i(TAG, "API client connected.");
Toast.makeText(getActivity(), "Successfully logged in", Toast.LENGTH_LONG).show();
DriveFolder s = Drive.DriveApi.getRootFolder(mGoogleApiClient);
String s1 = (Drive.DriveApi.getRootFolder(mGoogleApiClient)).getDriveId().toString();
DriveId sFolderId2 = DriveId.decodeFromString(s1);
DriveId sFolderId = (Drive.DriveApi.getRootFolder(mGoogleApiClient)).getDriveId();
DriveFolder folder = Drive.DriveApi.getFolder(mGoogleApiClient, sFolderId);
folder.listChildren(mGoogleApiClient).setResultCallback(rootFolderCallback);
// findAll(folder);
}
public ResultCallback<DriveApi.MetadataBufferResult> rootFolderCallback = new
ResultCallback<DriveApi.MetadataBufferResult>() {
#Override
public void onResult(DriveApi.MetadataBufferResult result) {
if (!result.getStatus().isSuccess()) {
return;
}
resultarray = new ArrayList<String>();
int hh = result.getMetadataBuffer().getCount();
for (int i = 0; i < result.getMetadataBuffer().getCount(); i++) {
resultarray.add(result.getMetadataBuffer().get(i).getTitle());
}
Toast.makeText(getActivity(), "Successfully listed files.", Toast.LENGTH_LONG).show();
}
};

UPDATE (Aug 25, 2015, 10:39 MST)
Based on your comment below, you have 2 options:
1/ Stay with the GDAA, use one of the INTENTS:
- Pick a file with opener activity
- Pick a folder with opener activity
See, GDAA does not let your app see anything it did not create (SCOPE_FILE only), but it still allows user to browse everything. If the user selects a file, it will become visible to you app. I don't know your app's intentions, so I can't say if this approach is usable.
2/ Switch to the REST with the DRIVE scope and your app will see everything (user has to approve up front). The basic CRUD implementation can be found here but make sure you change the scope in the init() method to 'DriveScopes.DRIVE'.
In case your app needs to iterate down the folder tree, collecting files in the process, both 'testTree()' and 'deleteTree()' methods in the MainActivity() do exactly that.
You may also stay with the GDAA and add REST functionality to it by adding
com.google.api.services.drive.Drive mGOOSvc = new Drive.Builder(AndroidHttp.newCompatibleTransport(), new GsonFactory(),
GoogleAccountCredential.usingOAuth2(appContext, Collections.singletonList(DriveScopes.DRIVE))
.setSelectedAccountName(email)
but you will sooner or later run into problems caused by GDAA caching / latency.
ORIGINAL ANSWER
Try this approach:
private static GoogleApiClient mGAC;
/****************************************************************************
* find file/folder in GOODrive
* #param prnId parent ID (optional), null searches full drive, "root" searches Drive root
* #param titl file/folder name (optional)
* #param mime file/folder mime type (optional)
* #return arraylist of found objects
*/
static void search(String prnId, String titl, String mime) {
if (mGAC != null && mGAC.isConnected()) {
// add query conditions, build query
ArrayList<Filter> fltrs = new ArrayList<>();
if (prnId != null){
fltrs.add(Filters.in(SearchableField.PARENTS,
prnId.equalsIgnoreCase("root") ?
Drive.DriveApi.getRootFolder(mGAC).getDriveId() : DriveId.decodeFromString(prnId)));
}
if (titl != null) fltrs.add(Filters.eq(SearchableField.TITLE, titl));
if (mime != null) fltrs.add(Filters.eq(SearchableField.MIME_TYPE, mime));
Query qry = new Query.Builder().addFilter(Filters.and(fltrs)).build();
// fire the query
Drive.DriveApi.query(mGAC, qry).setResultCallback(new ResultCallback<MetadataBufferResult>() {
#Override
public void onResult(MetadataBufferResult rslt) {
if (rslt != null && rslt.getStatus().isSuccess()) {
MetadataBuffer mdb = null;
try {
mdb = rslt.getMetadataBuffer();
if (mdb != null ) for (Metadata md : mdb) {
if (md == null || !md.isDataValid()) continue;
String title = md.getTitle();
DriveId driveId = md.getDriveId();
//.......
}
} finally { if (mdb != null) mdb.close(); }
}
}
});
}
}
Call it first with NULLs
search(null,null,null)
To list all the files in your Google Drive. You will see all the files your Android App created. But only those - FILE scope does not see anything else.
If you need to scan the directory tree, you may look closer at this GDAA demo, in MainActivity, there is are 'testTree()' / 'deleteTree() methods that recursively scan the directory tree structure.
Also, you may look at the answer here, it deals with a similar issue (especially the comments exchange under the answer).
Good Luck

Please note that you can use GDAA to retrieve the files and folder that you have either uploaded from the Android Device or downloaded via the drive app. This is to have more security (as quoted by Google).
In he code you need to ensure that you are trying all possible combinations for the files that may be present in your Google Drive account. For example, check if you are tracking the parent of a file or a folder. If this condition is not met your app wont be able to retrieve those specific files.
/** Get the list of parents Id in ascending order. */
private List<String> collectParents(String folderId, Map<String, String> folderIdToParentId){
String parentId = folderIdToParentId.get(folderId);
if (logger.isTraceEnabled()){
logger.trace("Direct parent of {} is {}", folderId, parentId);
}
List<String> ancestors = new ArrayList<String>();
ancestors.add(parentId);
if (folderIdToParentId.containsKey(parentId)){
ancestors.addAll(collectParents(parentId, folderIdToParentId));
return ancestors;
}
return ancestors;
}
See the full code here.

Android Google DriveFile metadata is cached and not fetched from the cloud

Burcu Dogan wrote some example code showing how to sync a local preferences file to the user's Google Drive appfolder, found here: https://github.com/googledrive/appdatapreferences-android
I've converted this example to use the current Drive SDK, now shipping with Google Play Services.
If I update the cloud Drive file with device 1, and then run the following code on device 2, I'm getting a stale "modified" timestamp from the metadata. I'm assuming this is because the results are from a local cache of the Drive file:
Step 1. Look up the preferences file by name, with a query:
/**
* Retrieves the preferences file from the appdata folder.
* #return Retrieved preferences file or {#code null}.
* #throws IOException
*/
public DriveFile getPreferencesFile() throws IOException
{
if (mDriveFile != null)
return mDriveFile;
GoogleApiClient googleApiClient = getGoogleApiClient();
if (!googleApiClient.isConnected())
LOGW(TAG, "getPreferencesFile -- Google API not connected");
else
LOGD(TAG, "getPreferencesFile -- Google API CONNECTED");
Query query = new Query.Builder()
.addFilter(Filters.contains(SearchableField.TITLE, FILE_NAME))
.build();
DriveApi.MetadataBufferResult metadataBufferResult =
Drive.DriveApi.query(getGoogleApiClient(), query).await();
if (!metadataBufferResult.getStatus().isSuccess()) {
LOGE(TAG, "Problem while retrieving files");
return null;
}
MetadataBuffer buffer = metadataBufferResult.getMetadataBuffer();
LOGD(TAG, "Preference files found on Drive: " +
buffer.getCount());
if (buffer.getCount() == 0)
{
// return null to indicate the preference file doesn't exist
mDriveFile = null;
// create a new preferences file
// mDriveFile = insertPreferencesFile("{}");
}
else
mDriveFile = Drive.DriveApi.getFile(
getGoogleApiClient(),
buffer.get(0).getDriveId());
// Release the metadata buffer
buffer.release();
return mDriveFile;
}
Step 2. Get the metadata for the file:
// Get the metadata
DriveFile file;
DriveResource.MetadataResult result = file.getMetadata(getGoogleApiClient()).await();
Metadata metadata = result.getMetadata();
// Get the modified dates
metadata.getModifiedDate();
More curiously, after running the code below (which just lists the appdatafolder files and their content) the metadata modified date, fetched above, becomes correct!! Why???
/**
*
* Simple debug activity that lists all files currently in Drive AppFolder and their contents
*
*/
public class ActivityViewFilesInAppFolder extends BaseActivity {
private static final String TAG = "ActivityViewFilesInAppFolder";
private TextView mLogArea;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Add a text view to the window
ScrollView layout = new ScrollView(this);
setContentView(layout);
mLogArea = new TextView(this);
layout.addView(mLogArea);
ApiClientAsyncTask<Void, Void, String> task = new ApiClientAsyncTask<Void, Void, String>(this) {
#Override
protected String doInBackgroundConnected(Void[] params) {
StringBuffer result = new StringBuffer();
MetadataBuffer buffer = Drive.DriveApi.getAppFolder(getGoogleApiClient())
.listChildren(getGoogleApiClient()).await().getMetadataBuffer();
result.append("found " + buffer.getCount() + " files:\n");
for (Metadata m: buffer) {
DriveId id = m.getDriveId();
DriveFile file = Drive.DriveApi.getFile(getGoogleApiClient(), id);
DriveContents contents = file.open( getGoogleApiClient(),
DriveFile.MODE_READ_ONLY, null).await().getDriveContents();
FileInputStream is = new FileInputStream(contents.getParcelFileDescriptor()
.getFileDescriptor());
try {
BufferedReader bf = new BufferedReader(new InputStreamReader(is, Charsets.UTF_8));
String line=null; StringBuffer sb=new StringBuffer();
while ((line=bf.readLine()) != null ) {
sb.append(line);
}
contents.discard(getGoogleApiClient());
result.append("*** " + m.getTitle() + "/" + id + "/"
+ m.getFileSize() + "B:\n [" + sb.toString() + "]\n\n");
} catch (IOException e) {
throw new RuntimeException(e);
}
}
buffer.release();
return result.toString();
}
#Override
protected void onPostExecute(String s) {
if (mLogArea != null) {
mLogArea.append(s);
Map<String, ?> values = PreferenceManager
.getDefaultSharedPreferences(ActivityViewFilesInAppFolder.this).getAll();
String localJson = new GsonBuilder().create().toJson(values);
LOGD(TAG, "Local: " + localJson);
LOGD(TAG, "File: " + s);
}
}
};
task.execute();
}
}
Is the metadata reading from a cached local copy, unless something kicks it?
Does anyone know how to force these APIs to always pull the results from the remote Drive file?

I have an answer to your question. Well 'kind of answer', and I'm sure you will not be happy with it.
I had used RESTful API in my app before switching to GDAA. And after I did, I realized that GDAA, another layer with timing delays I have no control over, is causing issues in an app that attempts to keep multiple Android devices synchronized. See SO 22980497 22382099, 22515028, 23073474 and just grep for 'requestSync'.
I was hoping that GDAA implemented some kind of GCM logic to synchronize 'behind-the-scenes'. Especially when there is the 'addChangeListener()' method that seems to be designed for that. It does not look to be the case (at least not around Sept 2014). So, I backed off to a true-and-tested scheme of using RESTful API to talk to Google Drive with DataProvider and SyncAdapter logic behind it (much like shown in the UDACITY Class here).
What I'm not happy about, is somewhat ambiguous documentation of GDAA using terms like 'synchronize' not telling us if it is 'local' of 'network' synchronization. And not answering questions like the SO 23073474 mentioned above.
It appears (and I am not a Google insider) that GDAA has been designed for apps that do not immediately synchronize between devices. Unfortunately this has not been mentioned here or here - see 1:59, costing me a lot of time and frustration.
Now the question is: Should I (we) wait until we get 'real time' synchronization from GDAA, or should we go ahead and work on home-grown GCM based sync on top of RESTful-DataProvider-SyncAdapter?
Well, I personally will start working on GCM sync and will maintain an easy-to-use miniapp that will test GDAA behavior as new versions of Google Play Services come out. I will update this answer as soon as I have the 'test miniapp' ready and up in GitHub. Sorry I did not help much with the problem itself.

Well, I just found the secret sauce to trick the new Drive API into reading metadata from the remote file instead of the local cache.
Even though reading metadata doesn't require the file to be opened, it turns out that the file needs to be opened!
So the working code to read the latest metadata from the cloud is as follows:
DriveFile file;
// Trick Google Drive into fetching the remote file
// which has the latest metadata
file.open( getGoogleApiClient(), DriveFile.MODE_READ_ONLY, null).await();
DriveResource.MetadataResult result = file.getMetadata(getGoogleApiClient()).await();
Metadata metadata = result.getMetadata();
// Get the modified date
metadata.getModifiedDate();
Question for Google -- is this working as intended? The metadata is cached unless you first open the file read_only?

Android: Working with drive application folder

I'm building application using Google Drive api. But app folder not working after uninstalling the app. Here is what I been trying to do:
public searchFiles(){
GoogleApiClient googleApiClient = getGoogleApiClient();
Drive.DriveApi.getAppFolder(googleApiClient).listChildren(googleApiClient)
.setResultCallback(metadataBufferCallback);
}
private final ResultCallback<DriveApi.MetadataBufferResult> metadataBufferCallback = new
ResultCallback<DriveApi.MetadataBufferResult>() {
#Override
public void onResult(DriveApi.MetadataBufferResult result) {
if (!result.getStatus().isSuccess()) {
// Error
return;
}
MetadataBuffer metadataBuffer = result.getMetadataBuffer();
DriveId driveId = null;
if(metadataBuffer.getCount() > 0){
Metadata metadata = metadataBuffer.get(0);
driveId = metadata.getDriveId();
}
metadataBuffer.close();
if(driveId != null){
// success
}
else{
// omg, why?
}
}
};
I am not working with filters just yet, I got only got one file there. If I replace getAppFolder with getRootFolder it works just fine.
Also it works when it's cached, but once I uninstall the application metadataBuffer.getCount() is always return 0, even so in drive it says that I have 23 bytes of hidden data.
What am I missing here?
*I asked the user for SCOPE_APPFOLDER in the permissions. And I am running a signed version of the app.

Google Drive Android API - Check if folder exists

I'm trying to figure out how to check if a folder exists in Google Drive using the new Google Drive Android API
I've tried the following, thinking that it would either crash or return null if the folder is not found, but it doesn't do that (just as long as it is a valid DriveId, even though the folder has been deleted).
DriveFolder folder = Drive.DriveApi.getFolder(getGoogleApiClient(), driveId));
If i try to create a file the folder I get from the above code, it does not crash either?
I'm clearly having a little hard time understanding how this new API works all to together, especially with the very limited tutorials and SO questions out there, and I'm really stuck on this one, so any input will be much appreciated.
Just to clarify my problem: I'm creating a file in a specified Google Drive folder, but if the folder does not exist (has been deleted by user), I want to create it first.

After a lot of research this is the code I ended up with. It works properly, but has an issue: When a folder is trashed in Google Drive it takes some time (hours) before the metadata I can fetch from my app is updated, meaning that this code can first detect if the folder has been trashed a couple of hours later the trashing event actually happened - further information and discussions can be found here.
public class checkFolderActivity extends BaseDemoActivity {
#Override
public void onConnected(Bundle connectionHint) {
super.onConnected(connectionHint);
DriveId folderId = DriveId.decodeFromString(folderId);
DriveFolder folder = Drive.DriveApi.getFolder(mGoogleApiClient, folderId);
folder.getMetadata(mGoogleApiClient).setResultCallback(metadataRetrievedCallback);
}
final private ResultCallback<DriveResource.MetadataResult> metadataRetrievedCallback = new
ResultCallback<DriveResource.MetadataResult>() {
#Override
public void onResult(DriveResource.MetadataResult result) {
if (!result.getStatus().isSuccess()) {
Log.v(TAG, "Problem while trying to fetch metadata.");
return;
}
Metadata metadata = result.getMetadata();
if(metadata.isTrashed()){
Log.v(TAG, "Folder is trashed");
}else{
Log.v(TAG, "Folder is not trashed");
}
}
};
}

If you're creating a folder based on it's existence status, the 'createTree()' method here does just that.
The following 2 code snippets list files/folders based on arguments passed ( inside a folder, globally, based on MIME type ...). The line with md.getTitle() is the one that you can use to interrogate files/folders.
GoogleApiClient _gac;
void findAll(String title, String mime, DriveFolder fldr) {
ArrayList<Filter> fltrs = new ArrayList<Filter>();
fltrs.add(Filters.eq(SearchableField.TRASHED, false));
if (title != null) fltrs.add(Filters.eq(SearchableField.TITLE, title));
if (mime != null) fltrs.add(Filters.eq(SearchableField.MIME_TYPE, mime));
Query qry = new Query.Builder().addFilter(Filters.and(fltrs)).build();
MetadataBufferResult rslt = (fldr == null) ? Drive.DriveApi.query(_gac, qry).await() :
fldr.queryChildren(_gac, qry).await();
if (rslt.getStatus().isSuccess()) {
MetadataBuffer mdb = null;
try {
mdb = rslt.getMetadataBuffer();
if (mdb == null) return null;
for (Metadata md : mdb) {
if ((md == null) || md.isTrashed()) continue;
--->>>> md.getTitle()
}
} finally { if (mdb != null) mdb.close(); }
}
}
void listAll(DriveFolder fldr) {
MetadataBufferResult rslt = fldr.listChildren(_gac).await();
if (rslt.getStatus().isSuccess()) {
MetadataBuffer mdb = null;
try {
mdb = rslt.getMetadataBuffer();
if (mdb == null) return null;
for (Metadata md : mdb) {
if ((md == null) || md.isTrashed()) continue;
--->>>> md.getTitle()
}
} finally { if (mdb != null) mdb.close(); }
}
}
The key is probably checking the "isTrashed()" status. Since 'remove' file on the web only moves it to TRASH. Also, deleting in general (on the website, since there is no 'DELETE' in the API) is a bit flaky. I was testing it for a while, and it may take hours, before the "isTrashed()" status is updated. And manually emptying the trash in Google Drive is also unreliable. See this issue on Github.
There is a bit more talk here, but probably unrelated to your problem.

So today the answer is out of date API.
So I have posted example of how to check the folder if exists with the new update of documentation:
fun checkFolder(name: String):Boolean {
check(googleDriveService != null) { "You have to init Google Drive Service first!" }
return search(name, FOLDER_MIME_TYPE)
}
private fun search(name: String, mimeType:String): Boolean {
var pageToken: String? = null
do {
val result: FileList =
googleDriveService!!
.files()
.list()
.setQ("mimeType='$FOLDER_MIME_TYPE'")
.setSpaces("drive")
.setFields("nextPageToken, files(id, name)")
.setPageToken(pageToken)
.execute()
for (file in result.files) {
Log.d(TAG_UPLOAD_FILE , "Found file: %s (%s)\n ${file.name}, ${file.id} ")
if (name == file.name) return true
}
pageToken = result.nextPageToken
} while (pageToken != null)
return false
}
private const val FOLDER_MIME_TYPE= "application/vnd.google-apps.folder"

You can try to get the metadata for the folder. If the folder doesn't exist, this will fail.