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limbo

Factory/Loader of mongoose

Deal with what

A rpc server for querying mongodb.
Exchange data/message cross applications.
Listen for the data's change and emit events.

Providers

mongo query via mongoose api
rpc query via rpc methods

Overwrite the mongoose model methods

AFAIK, we can use hooks or so called middlewares to modify the mongoose model object before save and remove functions, but it does not works on update function. There was even leaded to an argument on github, but the maintainers still don't pay their attension on this issue. So I decide to use some tricks to overwrite the mongoose model methods, and make the hooks work. For example, we have an update function in model, we need update the updatedAt key when we save data by update function, we can overwrite this function.

_update = UserModel.update
UserModel.update = (conditions, update) ->
  update.updatedAt or= new Date
  _update.apply this, arguments

In limbo, we supply an overwrite function to help you overwrite the same name function of each model.

limbo = require 'limbo'
db = limbo.use 'test',
  conn: mongoose.createConnection 'mongodb://localhost/test'
# Overwrite the update function
db.loadOverwrite 'update', (_update) ->
  (conditions, update) ->
    update or= new Date
    _update.apply this, arguments
# Load schemas
db.loadSchema 'User', UserSchema
# Then each update function will auto update the updateAt key when executed
db.user.update()

We use a currying way to ensure your function recieve the exactly arguments by the user given. So the origin function of model will give you in the wrapper function (in this example, it is _update).

As the same as loadStatics and loadMethods in limbo, the loadOverwrite function also have a plural version: loadOverwrites, you can pass a group of overwrite function to it.

Dependencies

axon/axon-rpc limbo use axon as message-oriented middleware, and use axon as rpc middleware.

Example

Attention!

Some methods in rpc provider is not enabled, here is some examples:

method chain cross functions is not allowed:
db.user.find({}).limit(1).exec(callback) => db.user.find({}, {limit: 1}, callback)
RegExp in conditions is not allowed:
db.user.find({email: /gmail.com/}, {limit: 1}, callback) => db.user.aggregate([{$match: {'email': {$regex: 'gmail.com'}}}, {$limit: 1}])
aggregate function in mongoose do not auto cast variables to ObjectId or anything else, so you should take case of these variables and do not use them in the rpc provider. (for the reason JSON only accept data)