Routing mechanism implemented in python

This is an experimental project about how to approach routing implementation.

Routing consists of two parts, one is the route register which used to declare paths with lambdas and methods and, optionally, query params. The other one is the processor which parse the url, takes the params out of it and returns the result.

Define a route

register function is available for registering routes. It has four params, which are the followings:

• route: define route that can be seen like: /, /users, /users/, /users/{id}/details/{address_id}/
• callback: lambda function which is executed if request falls on the route
• method: can be one of the well-known methods. Default to GET
• params: list of queryparams as a whitelist. Other queryparams wont be processed. Pathparams are optional here.

routing.register(route='/users', 
                 callback=(lambda name, email: users.create_user(name, email)),
                 method=routing.Methods.POST,
                 params={'name', 'email'})

routing.register(route='/users/{id}', 
                 callback=(lambda id: users.get_user(id)), 
                 method=routing.Methods.GET)

Process a call

process function takes the following three params and process it. The return value is the result of the executed lambda belongs to the route.

• path: the route
• query string params: dict of query params with their values
• method: the method of the call

resp_body = routing.process(event.get('path'), 
                            event.get('queryStringParameters'), 
                            event.get('httpMethod'))

process raises different kind of errors depending on the error in the path, query or method.

The following errors can be raised in case of failures.

• NoRouteFoundError: raised in case of no registered route found
• NoMethodFoundError: raised in case of no registered route found with the method
• RouteNotValidError: raised when route contains invalid chars
• QueryNotValidError: raised when query contains invalid chars

Response

The response body is the return value of the process function which can be an object or None in case of void return.

Entrypoint of a call

Considered as one entrypoint given, called handler, which requires two params, an event object which contains the abovementioned key-value pairs and a context.

It returns a response object which body is serialized by json.dump. Also contains status code and encoding.