CODEWITHSUNDEEP
ruby-on-railscachingmongodbmongoid
Kirill
Kirill

Reputation: 3737

Caching parent classes in mongodb

This is my data structure.

Foo  
  has_many: bar

Bar  
  belongs_to: Foo

I am trying to write a caching method for Bar that will pull out only "featured" entries.

def self.get_featured  
  Rails.cache.fetch("featured", :expires_in => 1.day) do  
    self.where(:featured=>true)   
  end  
end

That works. However, the views which display this data also call for information such as featured.foo.title which is not cached as part of the .get_featured method.

Every time I call something like that, the db gets hit again, which happens >40 times per page, thus causing the db to implode a little.

Question, how can I cache filtered Bar AND Foo information for all the filtered records of this Bar?

Upvotes: 0

Views: 189

Answers (1)

RameshVel
RameshVel

Reputation: 65857

You can use mongoid includes to eager load the data by specifying the relation names. But currently it is limited to 1 level deep. So i believe it will eager load the foo along with featured, but not sure about the bar. You can try it yourself

def self.get_featured  
  Rails.cache.fetch("featured", :expires_in => 1.day) do  
    self.includes(:foo,:bar).where(:featured=>true)   
  end  
end

In order to make it work, the Mongoid identity map must be enabled in the mongoid.yml like this

identity_map_enabled: true

Upvotes: 2

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