How to query MongoDB directly from Ruby instead of using Mongoid?

Question

I am writing a migration for a Rails application that uses MongoDB and Mongoid. My migration currently uses my models that use Mongoid to query and update records, but the performance is sub-par. I am essentially updating all records in a large collection and making n+20 queries. I killed the migration after taking an hour to run locally (and didn't finish). I would like to be able to run raw queries to mongo without too much effort. I'm assuming there is some way to access a mongo driver from Mongoid since Mongoid has already loaded a connection to the database. How can I access the database to run my update queries direcly?

Answer 1

If you're using Mongoid 3, it provides easy access to its MongoDB driver: Moped. Here's an example of accessing some raw data without using Models to access the data:

db = Mongoid::Sessions.default  # inserting a new document collection = db[:collection_name] collection.insert(name: 'my new document')  # finding a document doc = collection.find(name: 'my new document').first  # iterating over all documents in a collection collection.find.each do |document|   puts document.inspect end 

Answer 2

For Mongoid 5:

db = Mongoid::Clients.default  collection = db[:collection_name] 

Now we can perform queries on the collection

Answer 3

Here how you do it (This would work for 2+ and 3+ as well)

1) All your Model exhibit this behavior you have include Mongoid::Document inside all your model so technically each document is mapped in monogodb thru moped or mongodb-ruby driver via mongoid

so If you have model Like

class PerformerSource 
  include Mongoid::Document
  ## Definition

end

Now you can run Mongo Query using the driver (Moped or Mongodb-ruby driver) like this

PerformerSource.collection.insert("something")
## where something is json document you want to insert

This would give u the moped (if using mongoid 3) connection for that document

2) You can also do it something like this

 Mongoid::Sessions.default.collections.find { |document| document.name == "performer_sources"}.insert("something")

How to more on mongo query and how mongoid map those using moped u can follow this section of querying where it describe how query is acheived internally via moped

Hope this help

Answer 4

For Mongoid 6:

db = Mongoid::default_client
collection = db[:collection_name]