Cruet is a simple toolkit for building microservices with flask. It works with both, function based and class based views.
It is built on top of:
- flask
- marshmallow
- webargs
from flask import Flask
from marshmallow import fields
from cruet import Cruet, use_args, ApiError, ApiResponse
app = Flask(__name__)
cruet = Cruet(app)
@app.route('/')
@use_args({'name': fields.Str(required=True)})
def index(args):
if len(args['name']) < 3:
raise ApiError('Name has to be at least 3 characters', 400)
return ApiResponse({'msg': 'Hello ' + args['name']})
if __name__ == '__main__':
app.run()
# curl http://localhost:5000/?name='World'
# {"data": {"msg": "Hello World"}}
Cruet is available from PyPi
pip install cruet
Cruet provides the ApiResponse
class for building json responses that are formatted consistently across all endpoints.
Cruet provides the ApiError
exception class for raising an exception and returning a formatted json response with the error message.
Cruet uses the excellent webargs library for validating HTTP requests. It integrates the library in a very transparent way, which doesn't change the way webargs is being used and their documentation should be used as the reference. Cruet only adds its own error handling to webargs and provides convenient decorators for different HTTP request input types.
For general use, the use_args
and use_kwargs
decorators can be used. The example above uses use_args
to check for a parameter called name
. The webargs library uses the concept of locations to define where it should look for the HTTP request data.
Cruet provides a few convenient decorators for the most common locations.
The query
decorator looks for the data as part of the arguments in the URL query string.
from cruet import query
@app.route('/')
@query({'name': fields.Str(required=True)})
def index(args):
if len(args['name']) < 3:
raise ApiError('Name has to be at least 3 characters', 400)
return ApiResponse({'msg': 'Hello ' + args["name"]})
# curl http://localhost:5000/?name='World'
# {"data": {"msg": "Hello World"}}
The body
decorator looks for json formatted data in the request body.
from cruet import body
@app.route('/', methods=['POST'])
@body({'name': fields.Str(required=True)})
def index(args):
if len(args['name']) < 3:
raise ApiError('Name has to be at least 3 characters', 400)
return ApiResponse({'msg': 'Hello ' + args["name"]})
# curl -d '{"name":"World"}' -H "Content-Type: application/json" -X POST http://localhost:5000
# {"data": {"msg": "Hello World"}}
The form
decorator looks for form-urlencoded data.
from cruet import form
@app.route('/', methods=['POST'])
@form({'name': fields.Str(required=True)})
def index(args):
if len(args['name']) < 3:
raise ApiError('Name has to be at least 3 characters', 400)
return ApiResponse({'msg': 'Hello ' + args["name"]})
# curl -d "name=World" -X POST http://localhost:5000
# {"data": {"msg": "Hello World"}}