CODEWITHSUNDEEP
ruby-on-railsrubymongodbmongoid
gcstr
gcstr

Reputation: 1547

Mongoid Tags - Gather unique array items from model

I'm build a Rails application with Mongoid and I need tags in one of my models.

class Question
  include Mongoid::Document
  include Mongoid::Timestamps

  has_many :options
  belongs_to :user

  field :title, type: String
  field :options_count, type: Fixnum, default: 0
  field :tags, type: Array
end

It works well and I can get all Question's tags using any_in

Question.any_in(tags:'foo')

But how can I get all tags from all documents in Question?

I'm trying to use map/reduce but it looks like I'm just sweeping all documents and treating the arrays in Ruby and it just doesn't feel right.

map = %Q{
  function() {
    emit(this.title, {tags: this.tags});
  }
}

reduce = %Q{
  function(key, values) {
    var result = [];
    values.forEach(function(value) {
      result.push(value.tags);
    });
    return result.toString();
  }
}

map_reduce(map, reduce).out(inline: true).each do |doc|
  p doc['value']
end

Upvotes: 2

Views: 155

Answers (1)

victorkt
victorkt

Reputation: 14572

You can use db.collection.distinct for this. In your case, using Mongoid:

Question.distinct(:tags)

This will return an array of all tags in all documents with no repeated values.

Upvotes: 1

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