Google App Engine: Modifying 1000 entities
Question: I have about 1000 user account entities like this:

    
    
    class UserAccount(ndb.Model):
        email = ndb.StringProperty()
    

Some of these email values contain uppercase letters like
_JohnathanDough@email.com_. I want to select all the `email` values from all
UserAccount entities and apply python's `email.lower()`. How can I do this
efficiently, and most importantly, without errors?

Note: The email values are important for login, so I cannot afford to mess
this up. Is there a way to backup this data in case of the event that I do
make a mistake?

Thank you.


Answer: Yes, off course. Even if Datastore Administration is an experimental feature
we can backup and restore data without coding. Follow this instruction for the
backup flow: [Backing up
data](https://developers.google.com/appengine/docs/adminconsole/datastoreadmin#backing_up_data).
To processing your data instead, the most efficient way is to use the
[MapReduce
library](https://developers.google.com/appengine/docs/python/dataprocessing/).

