Use different mongodb instances in mongoid

By default, we save all the collections in one mongodb instance, or replicate/shard all of them into different mongodb instances. But what if saving a special collection into one mongodb instance, and the other collections into the other mongodb instance?

This is what I need to do with a mongoid project several weeks before. In common we just define a mongodb instance in the config/mongoid.yml, yep, you can define only one instance for one environment just like activerecord, the define the different mongodb instance in model.

class Ad
  include Mongoid::Document

  collection.master = Mongoid::Collections::Master.new(
    Mongo::Connection.new(AD_DB_HOST, AD_DB_PORT).db(AD_DB_NAME),
    AD_COLLECTION_NAME
  )
end

change the AD_DB_HOST, AD_DB_PORT, AD_DB_NAME and AD_COLLECTION_NAME with your mongodb configuration, the following is my configuration,

AD_DB_HOST => 'localhost'
AD_DB_PORT => 27018
AD_DB_NAME => 'ad_developmet'
AD_COLLECTION_NAME => 'ads'

and it would be better move these configurations into a config file.

Now when saving or reading the ads collection, it uses localhost:27018/ad_development, and the other collections use localhost:27017/project_development.

Posted in  mongodb mongoid

Comments

14 Jan 2011

Drop tmp collections in Mongodb

I'm trying mongodb map/reduce functionality with mongoid these days. I find there is a tmp.mr.mapreduce_ddd_ddd collection created after each map/reduce operation, it's ok that these tmp collections are used to hold output of map/reduce operation.

From mongodb document, it's said the temp collections will be cleaned up when the client connection closes or when explicitly dropped. But I never see these temp collections are dropped, when I print show collections, there are too many temp collections annoyed me, I decided to drop these temp collections explicitly.

db.system.namespaces.find({name: /tmp.mr/}).forEach(function(z) {
  try{
    db.getMongo().getCollection( z.name ).drop();
  } catch(err) {}
});

It finds all the namespaces whose names contain tmp.mr, if so, drop the collections.

Posted in  mongodb

Comments

06 Jan 2011

JQuery Plugin Template

JQuery is one of the most important javascript framework I used, besides default jquery apis, I use a lot of jquery plugins to improve the web interactive, such as auto complete, dropdown menu, chart and so on.

I will be likely to write some jquery plugins or hack others' jquery plugins, The following is the template for a jquery plugin that I learned from "jQuery 1.4 Plugin Development"

(function($) {
  $.fn.pluginName = function(options) {
    var defaults = {
      ......
    }

    var o = $.extend({}, defaults, options);

    return this.each(function() {
      var e = $(this);
      ......
    });
  }
})(jQuery);

the structure (function($) {...})(jQuery) can protected the conflict of $ sign which is used by other javascript framework.

$.extend({}, defaults, options) provides a flexible way to tweak your plugin, options can override defaults, but not change the value of defaults.

return this.each(function() {...}) promises your plugin functions are chainable, like the default jquery apis.

Posted in  jquery

Comments

20 Dec 2010

盛大创新院分享

昨天去盛大创新院做分享，主要是介绍我目前正在做的网站，rails-bestpractices.com

Rails bestpractices.com

盛大创新院还是很不错的地方，只可惜昨天他们一些做rails的牛人都在开会，失去了一个被拍砖的机会

Posted in  presentation

Comments

12 Aug 2010

将table的数据导出为csv

项目中经常会有这样的usecase，把一个table中的数据导出为csv，用fastercsv这个gem可以快速完成这个功能。

首先放一个导出csv的链接

= link_to 'Export to CSV', participants_path(:format => :csv)

然后在controller中生成相应的csv，并发送给用户

def index
  @participants = Participant.all

  respond_to do |format|
    format.csv {
      participants_csv = FasterCSV.generate do |csv|
        csv  ["First Name", "Last Name", "Age", "Gender", "Address", "Phone", "Email"]
        @participants.each do |p|
          csv  [p.first_name, p.last_name, p.age, p.gender, p.address, p.phone, p.email]
        end
      end
      send_data participants_csv, :type => 'text/csv', :filename => 'participants.csv'
    }
  end
end

其中用FasterCSV快速创建好csv数据，再通过send_data发送给客户端就可以了

Posted in  rails

Comments

20 Jul 2010

Fork me on GitHub