mercator 0.1.6

0.1.6

Mercator - Data Mapper for Protobuf
===================================

``version 0.1.6``

Python DSL to leverage translation of dictionaries and SQLAlchemy into Protobuf objects

.. image:: https://img.shields.io/pypi/pyversions/mercator.svg
:target: https://pypi.python.org/pypi/mercator
:alt: PyPi Project Page
.. image:: https://travis-ci.org/NewStore/mercator.svg?branch=master
:target: https://travis-ci.org/NewStore/mercator
:alt: Travis Build
.. image:: https://readthedocs.org/projects/mercator/badge/?version=latest
:target: http://mercator.readthedocs.io/en/latest/?badge=latest
:alt: Documentation Status
.. image:: https://codecov.io/gh/NewStore/mercator/branch/master/graph/badge.svg
:target: https://codecov.io/gh/NewStore/mercator
:alt: Test Coverage Reports


What is Mercator ?
------------------

Mercator is a Python library that simplifies the following of
serializing dictionary data into Protobuf binary data.

Mercator actually supports extracting data from:
- dictionaries
- SQLAlchemy model instances
- Any opaque python objects (e.g.: :py:class:`~collections.namedtuple`)


When should I use Mercator ?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

- When migrating custom implementations of RPC to gGRPC.
- When migrating in-memory data to Protobuf.


When should I **not** use Mercator ?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


- When writing gRPC services from scratch.
- When writing anything that uses Protobuf gets called.



Install
-------

.. code:: bash

pip install mercator


Documentation
-------------

`https://mercator.readthedocs.org <https://mercator.readthedocs.org>`_


Basic Usage
-----------


1. Given a protobuf declaration
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


.. code:: protobuf

syntax = "proto3";
package services.social_platform;

import "google/protobuf/timestamp.proto";

message User {
message AuthToken {
string value = 1;
google.protobuf.Timestamp created_at = 2;
google.protobuf.Timestamp expires_at = 3;
}
}


2. Declare Mappings
~~~~~~~~~~~~~~~~~~~

.. code:: python


from mercator import (
ProtoMapping,
ProtoKey,
ProtoList,
SinglePropertyMapping,
)
from google.protobuf.timestamp_pb2 import Timestamp
from google.protobuf.struct_pb2 import Struct
from google.protobuf import struct_pb2


ProtobufTimestamp = SinglePropertyMapping(int, Timestamp, 'seconds')

class UserAuthTokenMapping(ProtoMapping):
__proto__ = domain_pb2.User.AuthToken
value = ProtoKey('data', str)
created_at = ProtoKey('created_at', ProtobufTimestamp)
expires_at = ProtoKey('expires_at', ProtobufTimestamp)


class UserMapping(ProtoMapping):
__proto__ = domain_pb2.User

tokens = ProtoList('tokens', UserAuthTokenMapping)


3. Generate python files
~~~~~~~~~~~~~~~~~~~~~~~~

.. code:: shell

python -m grpc_tools.protoc -I ./ --python_out=./ --grpc_python_out=./ ./*.proto


4. Process data!
~~~~~~~~~~~~~~~~

.. code:: python


info = {
'login': 'Hulk',
'email': '[e-mail]',
'tokens': [
{
'data': 'this is the token',
'created_at': 1552240433,
'expires_at': 1552240733,
}
],
}

user = UserMapping(info).to_protobuf()

assert isinstance(user, domain_pb2.User)


Contributing
------------

#. Check the `code structure documentation <CODE_STRUCTURE.rst>`_
#. Write tests
#. Write code
#. Send a pull-request