Pactum

The HTTP-API specification sketchbook for pythonistas

pip install pactum

With Pactum you can specify HTTP-APIs using pure python.

Pactum is easy to use, easy to extend and easy to contribute:

Easy to use

The only requirements to start writing an API specification with pactum is pactum package itself and some knowledge of python.

import pactum

class MyAPI(pactum.API):
    name = 'My API'
    versions = [...]

Easy to extend

Using the visitor pattern you can create exporters and extensions for any format or service you want.

Take a look at pactum/exporters/openapi.py.

Architecture

Always keep this diagram in mind when defining your APIs.

Tutorial

Create a file called specs.py and start defining your API.

You can define a Resource object for your API.

from pactum import Action, API, Resource, Response, Version
from pactum import fields, verbs

class Order(Resource):
    fields = [
        fields.IntegerField(name='code', required=True),
        fields.TimestampField(name='created_at'),
        fields.StringField(name='item')
    ]
resource = Order()

error_resource = Resource(
    name = 'ErrorResource'
    fields = [fields.StringField(name='error', required=False)]
)

You can define any element of your specification by calling it directly as in error_resource or by class definition as in MyResource and then calling it.

List resources are definitions of lists of the same resource.

list_order_resource = ListResource(resource=resource)

You can define Response objects with status, description(optional) a header(optional) and a Resource/ListResource object as body (optionally)...

list_response = Response(
    status=200, description='Here is your orders list.', body=list_resource
)

detail_response = Response(
    status=200, description='Here is your order.', body=resource
)

error_response = Response(status=404, resource=error_resource, headers=[('Content-type': 'application-json')])

... and Request objects with verb, description, header(optional) and a Resource/ListResource object as payload.

get_request = Request(verb=verbs.GET)

An Action groups your request and a list of responses for a specified action passed in the description parameter.

list_action = Action(
    description='Returns a list of resources.',
    request=get_request,
    responses=[error_response, list_response]
)

detail_action = Action(
    description='Returns a resource based on its code.',
    request=get_request,
    responses=[error_response, detail_response]
)

The Action object, as all other elements in Pactum, receive a description string that sets the .__doc__ attribute and can be the docstring of the class if the object is defined by class definition.

A route can have a list of actions in an HTTP path.

class OrderListRoute(Route):
    path = '/orders'
    actions = [list_action]

list_route = OrderListRoute()

detail_route = OrderRoute(path='/orders/{code}', actions=detail_action)

Your routes can be grouped in API versions.

class V1(Version):
    name = 'V1'
    routes = [list_route, detail_route]

v1 = V1()

Then you can define your API. ;)

class OrdersAPI(API):
    name = 'Orders API'
    versions = [v1]

api = OrdersAPI()

Be happy and ready to export your specification to any format you want.

Exporting to openapi specs.

Pactum has a command that exports your specification to OpenAPI. You can call it by using:

pactum-openapi <spec_file.py> <output_file> [--format=<json or yaml>]

Road to version 1.

• Test elements .accept(visitor) methods.
• Support for version selectors (Versions should be specified on HTTP header, path, or custom fields)
• Stabilize the way we work with path parameters.
• Support for Authorization and Authentication Specifications.
• Support for extensions.
• Behaviors