I would like to have some data fixtures put into data store when my go project is deployed, similar to what can be done in Django. Is it possible? If not, are there any alternatives?
if your are looking for some configuration to put data into datastore, the answer is no. also the python and java versions of appengine don't have such feature.
what i think the django framework for appengine is doing, is the same as you could do.
just write the data you need to the datastore inside your app init method
also inside init you check if the data is already written.
then any time the app is startet, he checks if it should write some fixture data to datastore, and you can be sure that before first request is processed that its there.
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I am deploying a Plotly Dash app on Google App Engine but meet some difficulties. The data source to be queried in the dashboard is a Bigquery table, whose content is changing. I hope that the data in the App can always be the latest.
What I tried is at the beginning of the main.py code, I read in the table from Bigquery by Bigquery Python API, but after the App being deployed onto GAE, I found the data was fixed; even I deleted the Bigquery table, the App was not affected. May I know what is the correct way to get data from BigQuery to App Engine? Thanks.
How to connect to BigQuery from GAE using Python might be a bit more of a task than a single question can answer, but here are some hints:
Everything Google Cloud can (in my opinion) be best understood through the repositories on Github. For instance, the python docs samples contain several examples, out of which I think the client example is probably the easiest and most basic. Bigquery Python Samples are here. That will basically answer your question, except for a few gotchas I will mention.
You will of course need to download the client library to do development on a local environment. That is straightforward, but if something seems not to be working make sure you have enabled the API service account for your project--that can be a little confusing.
Something that is critically important to remember is that your GAE app will not be able to easily communicate with BigQuery if it is in a different region, and, in fact, once you set up a GAE app you cannot move or delete it! So, do pay attention to what you are doing as you set up, and if you have a locations mismatch you will need to migrate your BQ instance to the matching location.
I am very, very new to Google App Engine, but I need to administer a WebApp2 (so, Python) -based website that uses it. Specifically I need to filter a queryset and delete certain model instances.
Building the site locally is fine. Locally I can get at the models by hitting
http://localhost:8000/console
in my browser. This pulls up the "interactive console", and in there I can put some code like
from application.models.user import User
and it will work. From there I can create / delete User objects in the Datastore, so this local interactive console seems to have ORM-like functionality. (I'm coming from a Django background, so that's what it reminds me of).
However I don't seem to have this option on the live website. I was hoping to find it at
https://console.cloud.google.com/home/dashboard?project=<my project>
And I thought I had found it when I found the control to "activate google cloud shell". This brings up a command line on the web server, but the website's codebase doesn't seem to exist here, so launching the Python cli and trying to import the applications models like I can do locally doesn't work. And even if I could, I doubt it would be a Django-like ORM the way it is on my local build.
Am I thinking about this in the wrong way? How do you create / filter / delete / etc. Datastore objects via the backend in a GAE / WebApp2 website? Is the "Google cloud shell" even part of the answer?
To get access to your app code in the cloud shell one option would be to create in the shell a local copy of your app repository. For an example (addressing a different question, true) you can peek at Google Cloud: How to deploy mirrored Repository. But I'm not 100% certain if that will automatically give you access to your app's datastore. Worth a try IMHO.
Another option is to hook the desired operations as handler actions inside your app itself and execute them from there. Eventually hidden/protected/restricted via authentication, for example for admin users only. This is what I use for one-time datastore migrations that I need from time to time when I make changes to my entity models.
Finally, but not really a programatic access - you could use the Datastore page in the developer console to manually find, read and modify your entities, see Managing Datastore from the Console.
Use the remote_api_shell. You run this locally where your application code lives. Then you can import your models, and perform the same queries etc, and add modify/delete entities. I use this frequently for a range of tasks. Updating more than 100K records can become slow using this method.
https://cloud.google.com/appengine/docs/standard/python/tools/remoteapi
I and my friend are working on a GWT-Google App Engine project, using Tortoise SVN and Google Code to synchronize the code.
We also synchronize the local_db.bin file in appengine-generated folder. But we cant get it work. After synchronize the db file, our local datastore is not updated as we expected.
That is a pain. Im worrying about our future, when our database get bigger and more complicated #A#.
Anyone please give me an advice. What should i do to synchronize our local datastore?
I have to suggestions:
1) Use remote api : https://developers.google.com/appengine/articles/remote_api to share a GAE hosted db locally.
2) Maybe you can use Gdrive to sync folders.
This is a really bad idea. Even if you weren't having trouble making both ends read from the same datastore file, the local datastore is in a binary format, and thus you won't both be able to work on the app at the same time, or you'll get merge conflicts you will be unable to resolve.
Instead, both for collaboration purposes and for testing and deployment, you should provide a set of test data you can easily load into the datastore. Store the test data in version control, and load it in using bulkloader or your own code.
We have an application that we're deploying on GAE. I've been tasked with coming up with options for replicating the data that we're storing the the GAE data store to a system running in Amazon's cloud.
Ideally we could do this without having to transfer the entire data store on every sync. The replication does not need to be in anything close to real time, so something like a once or twice a day sync would work just fine.
Can anyone with some experience with GAE help me out here with what the options might be? So far I've come up with:
Use the Google provided bulkloader.py to export the data to CSV and somehow transfer the CSV to Amazon and process there
Create a Java app that runs on GAE, reads the data from the data store and sends the data to another Java app running on Amazon.
Do those options work? What would be the gotchas with those? What other options are there?
You could use a logic similar to what App Engine HRD migration or backup tool are doing:
Mark modified entities with a child entity marker
Run a MapperPipeline using App Engine mapreduce library iterating on those entity using a Datastore Input Reader
In your map function fetch the parent entity and serialize it to Google Storage using a File Output Writer and remove the marker
Ping the remote host to import those entity from the Google Storage url
As an alternative to 3 and 4, you could make multiple urlfetch(POST) to send each serialized entity to the remote host directly, but it is more fragile as an single failure could compromise the integrity of your data import.
You could look at the datastore admin source code for inspiration.
I am a fan of the extensibility of the CMSes. You can upload some code (usually PHP), authorize it from the CMS admin panel and it's running.
I wonder if it is possible in Google App Engine. I haven't checked the extensibility of existing CMSes for Google App Engine, but if there is any of them that supports plugins I would like to know how they did it, and whether they are JS plugins only, or if they support Python/Java plugins too.
Nick Johnson from Google wrote an entire blog post series on how to write a blog system for app engine. If it doesn't do what you want, I am sure that you can extend it but normally a blogging system is sufficient for a CMS for most people.
I don't have a public example to point to (sorry), but I can confirm that it is possible to create Python plugins for an App Engine project. I completed a project a few months ago that does something like this. The crux of the thing comes down to a single line of python:
exec plugincode in someDict
Above 'plugincode' is a string containing some python code to execute, and someDict is a dictionary of globals to execute it in. This is arguably cleaner than using eval(). In our case the globals dictionary contained an instance of an object that the plugincode used to communicate with the system. I can't think of any major limitations with this (or similar) approaches. e.g. plugincode could declare a class, and register an instance of that class as a callback handler etc etc.
In our case we stored the plugin code in the Data Store, and loaded it at appropriate times (e.g. when an instance of the app is started).
Actually I see no conceptual problem with supporting plugins in App Engine application. For example on Java you may fetch plugin jar to memory from data store or memcache (on application initialization phase), and then use custom class loader to load plugin classes as needed). Actually you even may load classes from request data and evaluate them on the fly if needed (how we do it in AppWrench Java console).
Regards,
Pavel.