Datetime with Mongodb/Mongoid and Rails 3 Not Populating

DateTime with MongoDB/Mongoid and Rails 3 Not Populating

Mongoid does not handle multiparameter attributes like Date yet, so you need to do the following:

# copied from: https://gist.github.com/315227
# add this to a new file in your lib directory
module MultiParameterAttributes
  def filter_time(attributes, name)
     attrs = attributes.collect do |key, value|
       if key =~ /^#{Regexp.escape(name.to_s)}\((\d+)(\w)\)$/
         [$1.to_i, value.send("to_#$2")]
       end
     end.compact.sort_by(&:first).map(&:last)
     Time.zone.local(*attrs) unless attrs.empty?
  end
end

# include the module above in your application_controller.rb
class ApplicationController < ActionController::Base
  include MultiParameterAttributes
end

# and in the controller action where you process the form params, use filter_time
class YourController < ApplicationController
  def your_action
    time = filter_time(params, :my_time_attribute_name)
  end
end

Some more info here:
http://groups.google.com/group/mongoid/browse_thread/thread/f83cbdd641581912

Mongoid document Time to Live

MongoDB (version 2.2 and up) actually has a special index type that allows you to specify a TTL on a document (see http://docs.mongodb.org/manual/tutorial/expire-data/). The database removes expired documents for you--no need for cron jobs or anything.

Mongoid supports this feature as follows:

index({created_at: 1}, {expire_after_seconds: 1.week})

The created_at field must hold date/time information. Include Mongoid::Timestamps in your model to get that for free.

UPDATE:

If you want to expire only a subset of documents, then you can create a special date/time field that is only populated for that subset. Documents with no value or a non-date/time value in the indexed field will never expire. For example:

# Special date/time field to base expirations on.
field :expirable_created_at, type: Time

# TTL index on the above field.
index({expirable_created_at: 1}, {expire_after_seconds: 1.week})

# Callback to set `expirable_created_at` only for guest roles.
before_create :set_expire, if: "role == :guest"
def set_expire
  self.expirable_created_at = Time.now
  return true
end

Emulating join behavior with Rails and Mongoid

I will start from the end:

I guess the attractiveness of mongodb is its javascript syntax and
similarity to json :)

Not only this, and json style is not main advantage. Main advantages of mongodb is ability to embedd documents, high performance and full scalability, full index support, map/reduce, etc.

So if I wanted flexibility and needed my data to join multiple times,
should I go with Postgresql?

It depends on concrete task, for example if you designing report system i prefer to use some relational database. But sometimes instead of joins and separate collections you can embedd documents + mongodb good fit for the data denormalization ( and in many situations you can denormalize in background to avoid joins )

I know mongodb has fast reads / writes but needs to query multiple
times to emulate joins. So when would this become a performance hit?

If you will use mongodb as regular relational database (without embedding and denormaliztion) you never achieve best performance.

Does mongodb limit your ability to create new complex relationships on
your data that did not previously exist?

No mongodb not limit you, because of it does not contains any constraints between collections like foreign key in any sql database + it allow embedd and easy denormalize data to fit your business needs and achieve best performance.

Rails 4 & Mongoid : date helpers

Arf, just found this question that mentions it has been removed in mongoid 4. I'll use this gem then

https://github.com/netguru/mongoid-sadstory

But if you have other alternatives....

Timestamp not updating in RoR application

My guess would be that you need to change the default value into a Proc.

In development mode, your models are being reloaded every request, so DateTime.now is always current. In production, however, the class is only loaded once (per dyno) during app startup, and DateTime.now results in a static value.

field :added_on, :type => DateTime, :default => Proc.new { DateTime.now }

should be what you want.

Rails 4/Devise/MongoDB: Unpermitted parameters using custom properties and strong parameters

I had the exact same issue and overriding sign_up_params did work for me

def sign_up_params
   params.require(:user).permit(:email, :password, :password_confirmation, :other, :etc)
end

of course, the difference is in that mine are just scalar values, while you're trying to mass assign a relation... I guess that's where you should look for.

By the way, the documentations is still inexistint in this topic (too new), and code commnents suggest to override devise_parameter_sanitizer, which isn't necessary.

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