Bottle-powered version of OSM XML → JSON proxy

gistfile1.py

#!/usr/bin/env python

import json
import urlparse

import bottle
import requests

from bottle import request, response, route
from bottle import install, uninstall
from lxml import etree


from json import dumps as json_dumps


class JSONAPIPlugin(object):
    name = 'jsonapi'
    api = 1

    def __init__(self, json_dumps=json_dumps):
        uninstall('json')
        self.json_dumps = json_dumps

    def apply(self, callback, context):
        dumps = self.json_dumps
        if not dumps: return callback
        def wrapper(*a, **ka):
            r = callback(*a, **ka)

            # Attempt to serialize, raises exception on failure
            json_response = dumps(r)

            # Set content type only if serialization succesful
            response.content_type = 'application/json'

            # Wrap in callback function for JSONP
            callback_function = request.query.get('callback')
            if callback_function:
                json_response = ''.join([callback_function, '(', json_response, ')'])

            return json_response
        return wrapper


install(JSONAPIPlugin())


@route('/<type>/<id:int>')
def fetch(type, id):
    if type not in ('node', 'way', 'relation'):
        abort('500', 'Primitive must be node, way, or relation')

    r = _fetch(type, id)

    if r is None:
        abort('404', 'Object not found')

    return r

def _fetch(item_type, item_id):

    url = 'http://api.openstreetmap.org/api/0.6/%s/%d' % (item_type, item_id)
    headers = {'user-agent': 'OSMPlaces JSON API Proxy (Contact: http://samat.org/contact.html)'}

    response = requests.get(url, headers=headers)

    # Request failed; may not exist, server error, etc
    if response.status_code != requests.codes.ok:
        return None

    out = {}
    root = etree.fromstring(response.content.encode('utf-8'))
    
    i = root[0] # Skip <osm/>; should we be iterating over all children here?
    out['type'] = i.tag # Save whether node, way, relation
    
    # Copy attributes on node/way/relation tag
    for k, v in i.items():
        # Store certain keys as int, float, bool, etc
        if k in ('changeset', 'uid', 'version', 'id'):
            v = int(v)
        if k in ('lat', 'lon'):
            v = float(v)
        if k in ('visible',):
            v = True if v.lower() == 'true' else 'false'
        out[k] = v
    
    # Copy tags
    tags = {}
    for t in i.iterfind('tag'):
        k, v = t.get('k'), t.get('v')
        tags[k] = v
    if tags:
        out['tags'] = tags

    # Create list of nodes for ways
    nodes = []
    for t in i.iterfind('nd'):
        nodes.append(int(t.get('ref')))
    if nodes:
        out['nodes'] = nodes
    
    # Copy members for relations
    members = []
    for t in i.iterfind('member'):
        a = {}
        for k, v in t.items():
            if k in ('ref',):
                v = int(v)
            a[k] = v
        members.append(a)
    if members:
        out['members'] = members

    return out

application = bottle.default_app()

if __name__ == '__main__':
    from bottle import run
    run(reloader=True)