https://github.com/theacodes/protopigeon
Helpers for datastore models and protorpc messages
https://github.com/theacodes/protopigeon
Last synced: 24 days ago
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Helpers for datastore models and protorpc messages
- Host: GitHub
- URL: https://github.com/theacodes/protopigeon
- Owner: theacodes
- License: other
- Created: 2014-10-06T02:06:45.000Z (over 10 years ago)
- Default Branch: master
- Last Pushed: 2015-01-14T15:54:48.000Z (over 10 years ago)
- Last Synced: 2025-04-25T04:48:09.727Z (about 1 month ago)
- Language: Python
- Size: 215 KB
- Stars: 9
- Watchers: 2
- Forks: 5
- Open Issues: 0
-
Metadata Files:
- Readme: readme.md
- License: license.txt
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README
Protopigeon
===========
Protopigeon provides utilities for generating [protorpc Messages](https://cloud.google.com/appengine/docs/python/tools/protorpc/#Working_with_Messages) from [ndb Models](https://cloud.google.com/appengine/docs/python/ndb/). It can generate Message classes from Models, translate entities to message instances and vice-versa. It can also compose multiple message classes together.
Usage
=====
Generating message classes from a model
---------------------------------------
If you have a model:
```python
class Actor(ndb.Model)
name = ndb.StringProperty()
shows = ndb.StringProperty(repeated=True)
rating = ndb.IntegerProperty()
```
You can easily generate a message class:
```python
ActorMessage = protopigeon.model_message(Actor)
```
You can also exclude fields, or specify which particular fields:
```python
ActorWithoutRatingMessage = protopigeon.model_message(Action, exclude=('rating',))
ActorRatingMessage = protopigeon.model_message(Action, only=('rating',))
```
Translating between entities and messages
-----------------------------------------
Playing on the previous example, if you have an entity (an instance of a Model) and want to make a message:
```python
doctor = Actor(name='Matt Smith', shows=('Doctor Who', 'Moses Jones'), rating=90)
doctor_message = protopigeon.to_message(doctor, ActorMessage)
doctor_no_rating = protopigeon.to_message(doctor, ActorWithoutRatingMessage)
doctor_rating = protopigeon.to_message(doctor, ActorRatingMessage)
```
If you have an instance of a message and you want an entity:
```python
doctor = protopigeon.to_entity(doctor_message, Actor)
```
You can even use this to update an existing entity (this works vice-versa with existing message instances too):
```python
new_doctor = protopigeon.to_entity(doctor_no_rating, Actor) # all fields but rating populated
protopigeon.to_entity(doctor_rating, new_doctor) # rating has been populated now, it's a complete entity.
```
Composing messages
------------------
If you have two or more messages classes that you'd like to combine into one message, we can do that too.
```python
class Origin(Message)
year = IntegerField(1)
location = StringField(2)
class Traveler(Message):
name = StringField(1)
species = StringField(1)
class Tag(Message)
urlsafe = StringField(1)
TravelerWithOriginAndTag = protopigeon.compose(Origin, Destination, Tag)
instance = TravelerWithOriginAndTag(
name='The Doctor',
year=2013,
location='Gallifrey'
species='Time Lord',
urlsafe='the_doctor'
)
```
Things that don't work
======================
At the moment, I do not have a clever solution for supporting computed properties. I may take the approach seen in the endpoints-proto-datastore and add a TypedComputedProperty. However, my goal was to not modify any Model classes if I didn't absolutely have to. I'm open to suggestions on this.
In the meantime it's pretty easy to fill in the data yourself using the above method of composing messages.
Installation
============
You can install easily with pip:
pip install --target lib protopigeon
Contributing
============
I graciously accept bugs and pull requests.
License
=======
Apache License, Version 2.0
Thanks
======
Special thanks to Danny Hermes and his [endpoints-proto-datastore](https://github.com/GoogleCloudPlatform/endpoints-proto-datastore) library, which helped me figure out a few quirky bits of ndb-to-message mapping. It's a much more comprehensive library and great if you want a more direct and magical approach to integrating protorpc, ndb, and endpoints.