michael schurter

import os
import pymongo
import pkg_resources
 
# Relative to distribution's root
SCRIPT_DIR = os.path.join('model', 'js')
 
def init_js(db):
    '''Initializes server-side javascript functions'''
    scripts = filter(
            lambda f: f.endswith('.js'),
            pkg_resources.resource_listdir(__name__, SCRIPT_DIR)
        )
    for script in scripts:
        # Name the function after the script name
        func_name, _ = script.split('.', 1)
        script_path = os.path.join(SCRIPT_DIR, script)
 
        # Create a pymongo Code object
        # otherwise it will be stored as a string
        code = pymongo.code.Code(
                pkg_resources.resource_string(__name__, script_path))
 
        # Upsert the function
        db.system.js.save({ '_id': func_name, 'value': code, })

function(x, y) {
    return x + y;
}

var1 = 1
var2 = 2
result = db.eval(pymongo.code.Code('add(a, b)', {'a': var1, 'b': var2,}))
assert result == 3

var1 = 1
var2 = 2
result = db.add(var1, var2)
assert result == 3

import string
 
from pymongo.code import Code
 
class ServerSideFunctions(object):
    def __init__(self, db):
        self.db = db
 
    def func_wrapper(self, func):
        '''Returns a closure for calling a server-side function.'''
        params = [] # To keep params ordered
        kwargs = {}
        def server_side_func(*args):
            '''Calls server side function with positional arguments.'''
            # Could be removed with better param generating logic
            if len(args) > len(string.letters):
                raise TypeError('%s() takes at most %d arguments (%d given)'
                        % (func, len(string.letters), len(args)))
 
            # Prepare arguments
            for k, v in zip(string.letters, args):
                kwargs[k] = v
                params.append(k) 
 
            # Prepare code object
            code = Code('%s(%s)' % (func, ', '.join(params)), kwargs)
 
            # Return result of server-side function
            return self.db.eval(code)
        return server_side_func
 
    def __getattr__(self, func):
        '''Return a closure for calling server-side function named `func`'''
        return self.func_wrapper(func)
 
dbjs = ServerSideFunctions('foo')
var1 = 1
var2 = 2
result = dbjs.add(var1, var2)
assert result == 3

assert db.js.add(1,2) == 3