MongoPopulator

mongo_populator populates a MongoDB database with placeholder data. It is built upon populator by Ryan Bates, but it works with the mongo gem in standalone scripts, and is not tied to any particular framework.

Installation

gem install mongo_populator

Usage

This gem adds a "populate" method to a Mongo::Collection. Pass the number of documents you want to create along with a block. In the block you can set the field values for each document.

require 'rubygems'
require 'mongo_populator'

db = Mongo::Connection.new("localhost", 27017).db("test-db")    

article_collection = db.collection('articles')
article_collection.populate(100) do |article|
  article.title       = MongoPopulator.words(4..6).capitalize
  article.slug        = article.title.downcase.tr(' ','-')
  article.published   = true
  article.created_at  = (Time.now - 604800)..Time.now
  article.body        = MongoPopulator.paragraphs(5..7)
end

Relationships

Unlike the original Populator, we are letting MongoDB set each ObjectId. This makes setting up relationships only slightly more laborious.

article_collection = db.collection('articles')
article_collection.populate(100) do |article|
  ...
end

# create array of article _ids to select from
article_ids = db.collection('article').distinct('_id')

comment_collection = db.collection('comments')
comment_collection.populate(1000) do |comment|
  ...
  comment.article = article_ids
end

That will create an average of 10 related comments for each article.

Shuffle through set of values

Passing a range or array of values will randomly select one.

...
person.gender = ['male', 'female']
...

This will create 1000 to 5000 men or women with the annual income between 10,000 and 200,000.

Fake values

If you need to generate fake data, there are a few methods to do this.

MongoPopulator.words(3) # generates 3 random words separated by spaces
MongoPopulator.words(10..20) # generates between 10 and 20 random words
MongoPopulator.sentences(5) # generates 5 sentences
MongoPopulator.paragraphs(3) # generates 3 paragraphs

For fancier data generation, try the Faker gem.

JSON-specific structures

To persist arrays in your documents, use either #items to save a certain number of items randomly selected from a set, or #array to save a specific array.

MongoPopulator.items(1..5, %w(ape bear cat dog elephant firefox)) # populates array with provided terms
MongoPopulator.items(10..20) # populates array with random words
MongoPopulator.array('red', 'green', 'blue') # saves `['red', 'green', 'blue']` exactly

Setting an attribute to nil prevents that attribute being set.

...
address.state = nil if address.country != "United States"
...

So, to support conditional setting of an attribute, pass it an array with one or more nils as elements.

...
user.creds = ['M.D.', 'J.D.', 'N.D.', nil, nil]  
...

~40% of users will not have credentials.

TODO

• Support singular and multiple embedded documents

Development

Problems or questions? Add an issue on GitHub or fork the project and send a pull request.

Special Thanks

MongoPopulator is highly derivative of, and heavily reuses, the work of Ryan Bates via Populator. Thanks, Ryan.

Special Thanks for the original Populator

Special thanks to Zach Dennis for his ar-extensions gem which some of this code is based on. Also many thanks to the contributors. See the CHANGELOG for the full list.