Dojo's Industrial-Strength Grid Widget

Listing 4. An ultra-simple Web server that provides slices of a very large (mock) data source for a dojox.grid.Grid client that uses a dojox.data.QueryReadStore to page the data on demand.

import cherrypy #do an "easy_install cherrypy" to get it
from cherrypy.lib.static import serve_file

import demjson #do an "easy_install demjson" to get it
import os
from random import randint #for building up mock data

json = demjson.JSON(compactly=False)
jsonify = json.encode

NUM_ITEMS = 1000000

class Content:
    def __init__(self):
        """
        Maybe you would call out to a db with some sql to get some 
        data based on the query string that comes into /data. For 
        now, we'll build up some static data to use.
        """

        self.items = []

        possible_item_labels = ["foo", "bar", "baz", "qux"]
        id=0
        for i in xrange(NUM_ITEMS):
            self.items.append({
                    'id' : id,
                    'label' : possible_item_labels[randint(0,3)]
            })
            id +=1

        #keep track of sort order b/c sorting is expensive...
        self.current_sort_order = ""

    @cherrypy.expose
    def data(self, **kw):
        """
        Serve up the data via http://localhost:8000/data

        kw will contain whatever is in your store's query. 
        By default the query string will come across as 
        something like:
        ?name=*&start=0&count=20 to populate the table

        Note: you may get into trouble if you have multiple users
        trying to access this url and changing the sort order of 
        items all at the same time (but relax, this is just 
        a little demo.)
        """

        #sorting the items by values for a given dictionary key...
        if kw.get('sort') and self.current_sort_order != kw.get('sort'):
            if kw['sort'][0] == '-': #descending order, slice off the -
                self.items.sort(lambda m,n:cmp(m.get(kw['sort'][1:]), \
                n.get(kw['sort'][1:])),reverse=True)
            else: #ascending order
                self.items.sort(lambda m,n:cmp(m.get(kw['sort']), \
                n.get(kw['sort'])))
            self.current_sort_order = kw['sort']

        #slicing the data...
        start = int(kw['start'])
        end = start + int(kw['count'])

        #serving up the slice of interest as well as the total size
        return jsonify({
            'numRows':NUM_ITEMS,
            'items':self.items[start:end],
            'identifier' : 'id'
        })

    @cherrypy.expose
    def index(self, **kw):
        """
        Serve up the web page through http://localhost:8000/
        """
        return serve_file(os.path.join(os.getcwd(), 'page.html')) 
        #the page containing the grid

cherrypy.server.socket_port = 8000
cherrypy.quickstart(Content(),'/')