Bottle Py: Enabling CORS for jQuery AJAX requests

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Install a handler instead of a hook.

There are two complementary ways I’ve done this in the past: decorator, or Bottle plugin. I’ll show you both and you can decide whether one (or both) of them suit your needs. In both cases, the general idea is: a handler intercepts the response before it’s sent back to the client, inserts the CORS headers, and then proceeds to return the response.

Method 1: Install Per-route (Decorator)

This method is preferable when you only want to run the handler on some of your routes. Just decorate each route that you want it to execute on. Here’s an example:

import bottle
from bottle import response

# the decorator
def enable_cors(fn):
    def _enable_cors(*args, **kwargs):
        # set CORS headers
        response.headers['Access-Control-Allow-Origin'] = '*'
        response.headers['Access-Control-Allow-Methods'] = 'GET, POST, PUT, OPTIONS'
        response.headers['Access-Control-Allow-Headers'] = 'Origin, Accept, Content-Type, X-Requested-With, X-CSRF-Token'

        if bottle.request.method != 'OPTIONS':
            # actual request; reply with the actual response
            return fn(*args, **kwargs)

    return _enable_cors


app = bottle.app()

@app.route('/cors', method=['OPTIONS', 'GET'])
@enable_cors
def lvambience():
    response.headers['Content-type'] = 'application/json'
    return '[1]'

app.run(port=8001)

Method 2: Install Globally (Bottle Plugin)

This method is preferable if you want the handler to execute on all or most of your routes. You’ll just define a Bottle plugin once, and Bottle will automatically call it for you on every route; no need to specify a decorator on each one. (Note that you can use a route’s skip parameter to avoid this handler on a per-route basis.) Here’s an example that corresponds to the one above:

import bottle
from bottle import response

class EnableCors(object):
    name="enable_cors"
    api = 2

    def apply(self, fn, context):
        def _enable_cors(*args, **kwargs):
            # set CORS headers
            response.headers['Access-Control-Allow-Origin'] = '*'
            response.headers['Access-Control-Allow-Methods'] = 'GET, POST, PUT, OPTIONS'
            response.headers['Access-Control-Allow-Headers'] = 'Origin, Accept, Content-Type, X-Requested-With, X-CSRF-Token'

            if bottle.request.method != 'OPTIONS':
                # actual request; reply with the actual response
                return fn(*args, **kwargs)

        return _enable_cors


app = bottle.app()

@app.route('/cors', method=['OPTIONS', 'GET'])
def lvambience():
    response.headers['Content-type'] = 'application/json'
    return '[1]'

app.install(EnableCors())

app.run(port=8001)

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