editable.py

# Editable Folder
#
# Author: luke hubbard - http://twitter.com/lukeinth
# 
# Simple interface and handler to serve editable files out of memcache, db, or disk.
# 
# Usage:
#  - save this file as editable.py
#  - create a folder called 'editable' and place your default css / html files in there
#  - add handler to webapp or django or whatever framework you use
#  - note this uses gaerun, see http://bit.ly/gaerun (you can comment out if you like)  
# 
# Example:
# 
# import wsgiref.handlers
# from google.appengine.ext import webapp
# import editable
#    
# def main():
#   application = webapp.WSGIApplication([
#     ('/editable/(.*)', editable.Handler),
#     ],debug=True)
#   wsgiref.handlers.CGIHandler().run(application)
#  
# if __name__ == '__main__':
#   main()

import gaerun
import os, sys
from google.appengine.api import memcache
from google.appengine.ext import db
import logging
import md5

def editable_key_name(folder, path):
    return md5.new(os.path.join(folder,path)).hexdigest()

EDITABLE_DIR = 'editable'

class EditableFile(db.Model):
    created_at = db.DateTimeProperty(auto_now_add=True)
    updated_at = db.DateTimeProperty(auto_now=True)
    content = db.TextProperty(required=True)

def load(path, folder=EDITABLE_DIR):
    key_name = editable_key_name(folder,path)
    logging.debug("Load editable file: %s key_name: %s" % (path, key_name))
    content = memcache.get(key_name, None)
    if content: 
        logging.debug("Load from memcache")
        return content
    editable_file = EditableFile.get_by_key_name(key_name)
    if editable_file:
        logging.debug("Load from DB")
        memcache.set(key_name, editable_file.content)
        return editable_file.content
    dirname = os.path.dirname(__file__)
    file = os.path.join(dirname, folder, path)
    if os.path.exists(file):
        logging.debug("Load from file")
        f = open(file)
        content = f.read()  
        f.close()
        EditableFile(key_name=key_name, content=content).put()
        memcache.set(key_name, content)
        return content  
        
def save(path, content, folder=EDITABLE_DIR):
    key_name = editable_key_name(folder,path)
    logging.debug("Save editable file: %s key_name: %s" % (path, key_name))
    editable_file = EditableFile.get_by_key_name(key_name) 
    if editable_file:
        editable_file.content = content
    else:
        editable_file = EditableFile(key_name=key_name, content=content)
    editable_file.put()
    memcache.set(key_name, content)
       
def restore(path, folder=EDITABLE_DIR):
    key_name = editable_key_name(folder,path)
    logging.debug("Restore editable file: %s key_name: %s" % (path, key_name))
    editable_file = EditableFile.get_by_key_name(key_name)
    if editable_file:
        editable_file.delete()
    memcache.set(key_name, None)

from google.appengine.ext import webapp

class Handler(webapp.RequestHandler):

    def get(self, path):
        import mimetypes
        content = load(path)
        if not content:
            self.error(404)
            return 
        (type, encoding) = mimetypes.guess_type(path)
        if type: 
            self.response.headers["Content-Type"] = type
        if encoding: 
            self.response.headers["Content-Encoding"] = encoding
        self.response.out.write(content)

if __name__ == "__main__":
    original = load('style.css')
    print original
    modified = original + "\nh2{color:black;}"
    save('style.css', modified)
    changed = load('style.css')
    print changed
    restore('style.css')
    restored = load('style.css')
    print restored