python-docar 0.9.1

python-docar is a Python module that gives an declarative syntax for defining messages passed between client and server applications. By moving the focus of web applications to the documents exchanged it gives you the possibility to implement document oriented architectures. In this way you can map documents (messages) to resources identified by URI's. The target applications are web apps that implement a RESTful interface.

On the server side those documents can be mapped to an underlying model store. At this time the django-orm mapper is supported. But python-docar is not really reduced to django. Other model mappers like sqlalchemy-orm or a mongodb mapper are possible.

The same document definitions can be reused on the client side. In the future it will come with a http client that can craft messages and send them right away to the server applications.

In the future those declarations should be able to enforce validation on those documents. That means, that on the client you can validate the message prior to sending the HTTP request and on the server prior to saving the resource to the data store.

At the moment the only messaging format supported is a very simple JSON format. It is planned to provide more dialects (like xml) or the possibility to override the builtin serializers.

python-docar is heavily influenced by roar.

Example

The following code is a simplified example of how to use python-docar. We start using the django backend:

# First declare your document
from webapp.models import EntryModel, AuthorModel
from docar import Document, Collection, fields

class Author(Document):
 name = fields.StringField()

 class Meta:
 backend_type = 'django'
 model = AuthorModel
 identifier = 'name'

class BlogEntry(Document):
 id = fields.NumberField()
 title = fields.StringField()
 body = fields.StringField()
 published = fields.BooleanField(default=False)
 author = fields.ForeignDocument(Author)

 class Meta:
 backend_type = 'django'
 model = EntryModel
 model_type = 'django' # The default atm
 #identifier = 'id' # The identifier defaults to 'id'

# You can also declare collections of documents
class Blog(Collection):
 document = BlogEntry

You can use those documents in the views of your app:

from webapp.documents import Author, BlogEntry, Blog

entry = BlogEntry({'id': 1})

# Bind the document to a model
entry.fetch()

I can also change attributes of the document and save it back to the model:

entry.title = "Hello World"
entry.save() # --> saves to the django model backend

The to_json method renders the document into a json message. It adds a few goodies to be a better REST player, like the link to itself. It could look like that:

# render the document as a json string
entry.to_json()

{
 "id": 1,
 "title": "Hello World",
 "body": "Long Text",
 "published": True,
 "author": {
 "rel": "related",
 "href": "https://example.org/author/crito/"
 },
 "link": {
 "rel": "self",
 "href": "https://example.org/entry/1/"
 }
}

There is another backend in development, that connects documents to a remote HTTP endpoint. The API is the same, only the underlying backend type differs. This can be used for client applications to connect to remote services using the same document declarations.

Installation

Clone yourself the latest source from github. Development happens fast, so its good to always go with the latest commit:

 git clone git://github.com/30loops/python-docar.git
 cd python-docar
 sudo python setup.py install

Development

This module comes along with a thorough test suite. Run it the following way:

 cd python-docar
 python setup.py nosetests


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Requirements:

· Python