Note. I'm using Google Cloud Python SDK version 1.9.3, on Ubuntu Linux 12.04, 64 bits. As I want this short intro to grow up in time I'll be using the excellent MVC framework "Ferris" from CloudSherpas from the beginning. The IDE I'm using is EMACS 23.3.
1. Creating your first "Person" Datastore model
1. Create a blank project
First you need to create an empty project to start with. To do so just make a copy of new_project template included with Google Cloud SDK. cp -R new_project_template my_new_project
2. Install Ferris MVC
Download Ferris MVC from the official site:
wget -c https://bitbucket.org/cloudsherpas/ferris-framework/get/master.zip Unzip the package in your "my_new_project" folder or directory
$ unzip cloudsherpas-ferris-framework-*.zip -d .
$ cd cloudsherpas-ferris-framework-*
$ mv * ../
$ rm -fr cloudsherpas-ferris-framework-* Edit your and save your app.yaml file so you know is your project
#my_new_project/app.yaml
application: my-new-app-id #.appspot.com
version: 1.0
Start your app for the first time just to check everything is ok
To start your app for the first time just launch the dev server like this.
$ dev_appserver.py my_new_project
Then open your browser at http://localhost:8080 (local app URL) and to http://localhost:8000 (local admin console).
3. Creating your first Datastore Model
For the purposes of this article we'll create a simple two-properties model for the Kind "Person". This model includes the "name" of the person an also a multi-value text field for saving tags related to this person. Following the directory structure we'd just created by copying Ferris to our project, we need to create our model under the folder app/models like this: (you can use the text editor or IDE of your choice). # app/models/person.py
from ferris import BasicModel
from google.appengine.ext import ndb
class Person(BasicModel):
"""
NDB Model for Person
name: StringProperty - Required
skills: StringProperty(repeated=True) - Optional
"""
name = ndb.StringProperty(required=True)
tags = ndb.StringProperty(repeated=True)
Once you create your model you can restart your development server (CTRL+C) and dev_appappserver.py my_new_project again.
Using the interactive console to test your model
Google's Cloud SDK contains a very nice administration app that includes an interactive console to test your code or data for different purposes. In this case, we are going to use the interactive console to test our simple Person model by creating new entries and do some queries against it.Mass creation of test entries with sample data
One of the things that I find most annoying when testing some app is the lack of real or at least close to real data. A lot of problems (think of performance, scalability, validation and data modeling problems just to name a few), can be tracked down during early stages of development if just one can count on an adequate dataset to work with. Even for our simple model is good to have a decent size dataset to play with queries and insertions over tags or names in it.Although the developement server included with the GC SDK appears to have utilities to mass insert data into Google's Datastore, I could not found a good resource or reference to execute that procedure when one is using NDB (the official doc, mentions DB but not NDB implementation). In this scenario i'd remembered excelent Perl::Maker package and decided to search for an equivalent for Python. What i'd found was "Faker", a very simple yet powerful tool for creating user data: names, surnames and general paragraphs (lorem ipsum), so, what we are going to do right now is to add Faker to our project and start using the Interactive Console to do some tests.
1. Download Faker from official github site
https://github.com/joke2k/faker2. Unzip Faker inside your project folder
$ cd my_new_project
$ unzip faker-master.zip -d .
$ mv faker-master faker
3. Creating mass data from Interactive Console
Start your development server (if you didn't already)
$ dev_appserver.py my_new_project
Launch de Admin Console
Point your browser to http://localhost:8000 then click on "Interactive Console" from the left menu bar
Once there clear the default code in the text box.
Finally copy and paste the following python code in the text box:
from app.models.person import Person from google.appengine.ext import ndb from random import randrange from faker import Faker # a new instance of Faker fake = Faker() NENTRIES = 10 # a list wich contains fake tags to randomize over ftags = (['engineering','custom-making','writing','electrician', 'interiors-design','dancing','smiling','drifting','drinking']) ftags_new = [] for i in range(1,NENTRIES): # create a new name fname = fake.name() # randomize over tags list size and items to create the person's tags # randomize the number of tags for j in range(0,randrange(9)): # randomize tags ftags_new.extend([ftags[randrange(9)]]) print ftags_new person = Person(name=fname, tags=ftags_new) del ftags_new[:] # save the new person on datastore everytime person.put()
After executing the code above you should see a printed list of all tags list random assigned to each new entry.
['interiors-design', 'writing', 'electrician', 'dancing', 'interiors-design', 'drinking', 'smiling', 'interiors-design'] ['electrician', 'writing'] ['interiors-design'] ['interiors-design', 'interiors-design', 'dancing', 'smiling', 'smiling'] ['drifting', 'electrician', 'dancing', 'interiors-design', 'dancing', 'drinking'] ['electrician', 'writing', 'drifting', 'writing', 'writing', 'drinking', 'interiors-design', 'engineering'] ['interiors-design', 'interiors-design'] ['writing'] ['drinking', 'drinking', 'drinking', 'engineering']
Now you can go to "Datastore Viewer" in the console to see the entries you'd just created. In this case you'd created just 10 entries, but rhe number can be higher.
In the next part we'll be covering querying against Datastore and the repeated attributes and also some very nice options for timing your entries creation process.
References
[1] Google's App Engine Official Documentation https://developers.google.com/appengine/?csw=1[2] Ferris MVC http://ferris-framework.appspot.com
[3] Faker - https://github.com/joke2k/faker
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