I may sound noob while asking this.
I want to build a mechanism where, when a value of property of Google Datastore's entity changes, the corresponding user(email is present in some another property value for same entity) should be notified of the change. Does Google Datastore support this kind of mechanism, which is similar to Redis PubSub?
Any ideas how to integrate Google PubSub or webhooks with Google Datastore?
Also how to determine that the user is currently active i.e. how to check if the user has my gae application open in his browser?
Google Datastore doesn't have such mechanism. The only way is to send notification from your app, when your code updates datastore.
Totally possible. If you are using the NDB datastore and Python, for example, you would define in your model a _post_put_hook function. Every time an entity of this model changes, your code will be called. Your code can then look up the user and send them an email (or take whatever other necessary action).
Here is the relevant Python documentation for Model Hooks:
https://cloud.google.com/appengine/docs/python/ndb/entities#hooks
I hope that answers your question.
Related
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
Is there a way to create a new Datastore entity kind via some interactive means for Go App Engine apps? The datastore viewer won't let me add new entity kinds, and the interactive console doesn't seem to support Go.
I'm trying to upload some configuration data to datastore, including sensitive data that I don't want to appear in code. So far the best method I can come up with is to write some code to write an empty configuration entity, deploy, run, then use the datastore viewer to set the values.
Thanks in advance.
You absolutely can add new Entity Kinds in the Console.
In the Cloud Console, Click on the Datastore menu item, then 'Create an Entity'. Handy link, just select your project name
Then in the Kind field, just type in your desired Kind name.
First of all your code is safe at AppEngine - nobody can download it. At least nobody outside of Google. You can deploy it to a dedicated version/module and restrict usage to yourself (check current user, ask pass-phrase, etc in your code).
Second you can use Remote API - this way you do not upload any code to AppEngine. You can create entities remotely as you wish using secure HTTPS connection.
I am somewhat new to Web development - specifically Google App Engine and JavaScript/HTML development, but I have an app deployed and working on Google App Engine and it is working ok.
I would like a user of my App to be able to store and retrieve a serialization of the app state in JSON using the GAE Datastore. (Note - This is only a user-initiated action - so channels seem to be overkill)
The examples provided by Google demonstrates one approach that allows the server-side Python implementation to do this. Specifically https://developers.google.com/appengine/docs/python/gettingstartedpython27/usingdatastore. I have this working ok.
But this approach seems rather inelegant especially if as an "app" I want to store and retrieve serialized chunks of data somewhat asynchronously without reloading the page/app each time (again, this is only ever user-initiated).
I have not been able to find any high-level guidance on an approach to do that (assuming it is possible).
Any suggestions/links/examples would be greatly appreciated.
Thank you!
Jeff
As with many things, this depends on your specific needs. If you just want direct access to datastore storage, the datastore is exposed as an independent service with an API.
If you instead want to assert logic over the usage and interact with your app in some fashion, you may also want to look at Google Cloud Endpoints. With an endpoints API, you gain a more structured API you can call directly from javascript, or generate client libraries to be consumed by other languages/platforms.
I am working on a project on Google AppEngine, where I am using the datastore and memcache. For testing purposes, I go to the control panel, change and save of some values of some saved entities in the datastore. However, since they're already in memcache, I assume, the changes don't reflect on the application.
Using Admin/control panel, is there a way to enforce reloading these entities into memcache from the datastore, or at least to clear memcache?
Thank you,
Hazem
With the release of SDK 1.6.4 today a memcache page has been added to the production admin dashboard. It has a button that lets you flush memcache (as well as other features).
That does not solve the problem of automatically managing the memcache version of your entities. For that you could look into the NDB library (new standard library in SDK 1.6.4) which automatically caches your entities as you use them and invalidates the cache as necessary. It has lots of other features as well. I have not used it yet but it certainly sounds good: http://code.google.com/appengine/docs/python/ndb/
UPDATED March 27 now that SDK 1.6.4 has gone final and I can confirm it contains the memcache control panel.
As an alternative: I believe you could use Remote API, fire up a shell and execute e.g. memcache.flush_all()
no there isnt.
make a handler that does that for you and when you need to flush memcache you can simply hit that url
in Google App Engine,after using the makePersistent() to store the data in the datastore,i know how to get the data content by the key using getObjectById().
but now i wanna to get the data in the datastore by url. i think the url is created .
so the question is how the url can be created to get the data in the datastore
There is no built-in means to access the datastore through URLs. If you choose to, your application can implement URLs that return data from the datastore.
I invite you to take a look at titan-files. It's a powerful file-system abstraction on top of the DataStore and/or blob store. I'm using it for a commercial application and so far I've been very happy with it.