Firstly, thank you to @slangley and the team for asking me to guest post here. I really hope this helps you PHP folks on App Engine.

TL;DR – I can has code?

Sure, no problem. https://github.com/tomwalder/php-gds

Introduction

PHP on Google App Engine went Generally Available earlier this year, and that’s pretty awesome.

Certainly for me (and probably some of you) it makes both prototyping and running super-scalable web applications really easy and reliable.

Whilst the PHP part of the App Engine environment is ultra easy to use and scalable, you are likely to need a similarly featured data persistence layer for any useful applications. MySQL is cool and all, but it costs money (via Cloud SQL) and can’t scale automatically in the same way App Engine can.

Enter Cloud Datastore.

It’s pretty sweet – auto-scaling, distributed, supports transactions, mostly schema-less, managed, free to get started (up to 1GB of data and 50k queries per day).

So, you ask yourself, how do I use this amazing thing? Well until not that long ago it was a bit of a pain. you needed loads of glue code to get even the basics running.

So the php-gds library was built to simplify usage of Datastore from PHP. It tries to make it really, really easy to get started, whilst also being feature rich. It’s seeing a fair amount of adoption as far as I can tell, and the guys at Google are pretty keen on it too – hence this post!

Example – Write to Datastore

For any code running on the local development server or on a real App Engine application, it’s this easy…

// Build a new entity
$obj_book = new GDS\Entity();
$obj_book->title = 'Romeo and Juliet';
$obj_book->author = 'William Shakespeare';
$obj_book->isbn = '1840224339';

// Write it to Datastore
$obj_store = new GDS\Store('Book');
$obj_store->upsert($obj_book);

Example – Read from Datastore

Again, I try to make reading data is simple and intuitive as possible…

$obj_store = new GDS\Store('Book');
foreach($obj_store->fetchAll() as $obj_book) {
    echo "Title: {$obj_book->title}, ISBN: {$obj_book->isbn} <br />", PHP_EOL;
}

Native Access or JSON API

The php-gds library uses the native, Protocol Buffer APIs to access the Datastore – this means it is super fast.

It also supports remote access using the JSON API – in fact, you can use the same code against both, just passing the right Gateway object into your Store. More details on GitHub here.

Query Language – GQL

At the time of writing, php-gds uses the GQL, which is very similar to SQL, to query Datastore – and parameter binding, which is recommended.

$obj_book_store->fetchOne("SELECT * FROM Book WHERE isbn = @isbnNumber", [
    'isbnNumber' => '1853260304'
]);

Best Practice – Define a Schema/Model

You will get more (for less) if you define your Schema clearly, including what fields in your data to index. Indexing costs money (above the free quota) so it’s a good move to think about and define your model

More detail on defining a model can be found here.

Further Reading

There is a pretty decent set of guidance in the GitHub README and in the examples.

Support

Create an issue on GitHub or post on SO.

About Me

My name is Tom Walder, I’m CTO at Docnet, an e-commerce platform and solutions provider based in Manchester, UK. You can find me on twitter @tom_walder

I am the author of the php-gds Datastore library for PHP.