Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.python > #66908 > unrolled thread

Google app engine database

Back to article view | Back to comp.lang.python

Contents

  Google app engine database glenn.a.isaac@gmail.com - 2014-02-22 16:39 -0800
    Re: Google app engine database Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-02-23 00:57 +0000
    Re: Google app engine database Kev Dwyer <kevin.p.dwyer@gmail.com> - 2014-02-23 09:56 +0000

#66908 — Google app engine database

Is there a way to make sure that whenever you're making google engine app iterations to a database that that info does not get wiped/deleted.  Please advise

[toc] | [next] | [standalone]

#66909

On 23/02/2014 00:39, glenn.a.isaac@gmail.com wrote:
> Is there a way to make sure that whenever you're making google engine app iterations to a database that that info does not get wiped/deleted.  Please advise
>

What Python code have you tried or are you contemplating using?

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com

[toc] | [prev] | [next] | [standalone]

#66931

glenn.a.isaac@gmail.com wrote:

> Is there a way to make sure that whenever you're making google engine app
> iterations to a database that that info does not get wiped/deleted. 
> Please advise

It's not clear what you mean here; I'll guess that by "iterations" you mean
"changes" by "database" you mean the db or ndb datastore and by "info" you 
mean "data stored in the datastore".  Apologies if this isn't so.

Appengine doesn't document any migration utilities to handle changes in your 
datastore schema, so you need to manage the effects of such changes 
yourself.

To ensure that you do not lose data when changing your model code, avoid 
making destructive changes to your models, i.e.

 - don't delete properties from a model
 - don't rename properties on a model 

If you must make these changes for some reason, you'll need to migrate the 
data somehow.

In my experience with Appengine, data is not actaully lost if you make 
destructive changes to your models, it becomes inaccessible becuae the 
property names it was stored under no longer exist on the model.  In theory 
you could access the data by adding the proprties back to the model or 
(maybe) by loading a different model definition in the remote shell, but 
this is not something that you would want to rely on in a production 
environment.

tl,dr: it's ok to add new properties to you models, but don't remove or 
rename properties.

Hope that helps,

Kev

[toc] | [prev] | [standalone]

Back to top | Article view | comp.lang.python

csiph-web