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Project description

Pdef Python
===========
Python code generator for [Pdef compiler](https://github.com/pdef/pdef)
and Python implementation of descriptors, JSON format and HTTP RPC.

Structure
---------
- **generator**: Pdef code generator for Java.
- **python**: Python descriptors, JSON and HTTP RPC implementations.
- **example**: Example python project.

Requirements
------------
Python 2.6 or Python 3.3+.


Installation
------------
- Code generator:
```bash
$ [sudo] pip install pdef-java
# or
$ [sudo] easy_install pdef-java
```

Or [download](https://github.com/pdef/pdef-python/releases) the release,
unzip it and in the `generator` directory run:
```bash
$ [sudo] python setup.py install
```

The python generator will appear in the installed generators:
```bash
$ pdefc generate -h
usage: pdefc generate [...]
available generators:
- python: Python code generator, supports module names, does not support prefixes.
```

- Python package:
```
$ [sudo] pip install pdef
# or
$ [sudo] easy_install pdef
```

Or add it as a requirement to your project in `setup.py` or in pip `requirements.txt`.
See [releases](https://github.com/pdef/pdef-python/releases) for the latest version.

Code generation
---------------
Pass a pdef package path or a url to the compiler:
```bash
$ pdefc generate https://github.com/pdef/pdef/blob/master/example/world.yaml \
--generator python
--out generated
```

The generator supports mapping pdef modules to python modules via the `--module` argument.
```bash
$ pdefc generate https://github.com/pdef/pdef/blob/master/example/world.yaml \
--generator python
--module world.space:world_space
--module world:world_api
--out generated
```

Messages
--------
Generated messages implement `__eq__`, `__copy__`, `__deepcopy__`, and `__str__` magic methods,
and merging methods. The messages are not thread-safe. The examples are based
on the [pdef example package](https://github.com/pdef/pdef/tree/master/example).

```python
human = Human(id=1, name="John")
human.location = Location(lat=30, lng=40)
human.birthday = datetime.datetime(1900, 1, 2)

import copy
another = copy.deepcopy(human)

assert copy == human
```

Messages support merging which deep copies fields from a source message to a destination one.
```
human = Human(id=1, name="John")

another = Human()
another.merge(human)

assert another == human
```

Messages try to be None-safe and return default values for empty fields.
If an empty field is a collection or a message then it is initialized to an empty
object on the first access.
```python
# All properties return default values when the fields are empty.
human = Human()
assert human.id == 0
assert human.name == ""

# Special properties allow to check if the field is present.
assert not human.has_id
assert not human.has_name

# Absent collection and message fields are initialized to empty objects on first access.
continent = Continent()
assert not continent.has_humans

# The collection is initialized to an empty one.
continent.humans.append(human)
assert continent.humans == [human]
```

JSON Format
-----------
Pdef uses built-in json parser/serializer:
```python
# From a JSON-compatible dictionary.
human = Human.from_dict({
"id": 123
"name": "John})

# From a JSON string.
s = get_json_string()
human = Human.from_json(s)

# From a file-like object.
with open('human.json', 'rt') as f:
human = Human.from_json_stream(f)
```

Serialization:
```python
# To a JSON-compatible dictionary.
d = human.to_dict()

# To a JSON string.
s = human.to_json(ident=None)

# To a file-like object.
with open('myfile.json', 'wt') as f:
human.to_json_stream(f, indent=None)
```

Use `pdef.jsonformat` to read/write other pdef data types:
```python
# Write a list of ints to a JSON-string.
list0 = [1, 2, 3]
listd = pdef.descriptors.list0(pdef.descriptors.int32)
s = pdef.jsonformat.write(list0, listd)

# Read a list of ints from a JSON-string.
list1 = pdef.jsonformat.read(s, listd)
assert list0 == list1
```


HTTP RPC Client
---------------
RPC clients are thread-safe.

Create a default HTTP RPC client based on [requests](http://www.python-requests.org/en/latest/).
```python
client = pdef.rpc_client(World, url='http://example.com/world/')
world_client = client.proxy()

# Execute a remote method.
humans = world.humans().all(limit=10, offset=0)

# Execute a void remote method.
world.switchDayNight()
```

Full client example:
```python
# Create a requests session.
session = my_requests_session()

# Create an rpc client.
client = pdef.rpc_client(World, url='http://example.com/world/', session=session)

# Create an interface proxy with the client as an invocation handler.
proxy = pdef.proxy(World, invocation_handler=client)

# Execute a remote method.
proxy.humans().all(limit=10)
```

HTTP RPC Server
---------------
RPC handlers are thread-safe.

Create an rpc handler and a WSGI application:
```
world = get_my_world()
handler = pdef.rpc_handler(World, world)
wsgi_app = pdef.wsgi_app(handler)
# Pass the app to a web server.
```

To support other frameworks (such as Django, Flask, etc.) you need to convert custom requests
into `RpcRequests` and handle `RpcResults`.
```python
# In Django something like this will work.

# urlpatterns
urlpatterns = patterns('',
url(r'^myapp/api/(?P<path>\.+)$', 'myapp.views.api'),
)

# views
def api(request, path):
# Convert a django request into an rpc request.
rpc_req = RpcRequest(method=request.method, path=path)
rpc_req.query = request.GET
rpc_req.post = request.POST

# Handle the rpc request.
handler = get_rpc_handler()
success, rpc_result = handler(rpc_req)

# Convert the rpc result into a django response.
response = HttpResponse(rpc_result.to_json(), content_type="application/json;charset=utf-8")
if success:
# It's a successful result.
response.status_code = 200
else:
# It's an expected application exception.
response.status_code = 422 # Unprocessable entity.

# Send the response.
return response
```

License and Copyright
---------------------
Copyright: 2013 Ivan Korobkov <ivan.korobkov@gmail.com>

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at:

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

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