CODEWITHSUNDEEP
ruby-on-railsmongodbmongoid
crazybob
crazybob

Reputation: 2317

Mongoid - get a field from document

I have the following model

class MyModel
  field :title,           type: String
  field :url,             type: String
end

I would like to make a query that will return only the title field for each document.

How can I do it?

Upvotes: 0

Views: 141

Answers (1)

mu is too short
mu is too short

Reputation: 434665

Use only or without:

Queryable#only

Limit the fields that are returned to the provided fields.

Queryable#without

Limit the fields that are returned everything except the provided fields.

So you'd say:

MyModel.query_method_calls.only(:title)
# or
MyModel.query_method_calls.without(:url)

Note that only will make a mess of things if you're using Mongoid3 with the Identity Map enabled, you'll get half-formed objects stuck in the identity map cache and end up wondering where all the strange nil attributes are coming from. If this applies to you then bypass Mongoid and use the underlying Moped interface:

Query#select

Select the fields you want returned.

This approach would look like:

MyModel.collection.find(...).select(:title => 1)

You'd be working with hashes instead of Mongoid objects in this case.

Upvotes: 1

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