October 2015
Intermediate to advanced
368 pages
8h 49m
English
Content preview from Mastering Google App EngineBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Transactions
There are cases where you'd want a number of operations to succeed or fail altogether and nothing in between. This is called a transaction, and App Engine's datastore offers support for transactions. In App Engine, you do this by encapsulating all the steps that you want to fail or succeed together in a function and decorate it with the ndb.transactional decorator.
Let's suppose that it so happens that we add a new property called city to indicate the city that the car is in. Sometimes, two cars are exchanged between two dealers in two difference cities. In that case, we need to update the cities of these two listings and basically swap them. There are multiple datastore operations involved here, given that we have keys for both the ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.