How do I query for an Activity that has 3 tags?

Question

I have the following models:

activity.rb

tag.rb

tagging.rb

Tagging is a join model for activity and tag.

I would like to search an Activity that has 2 or more tags. How do I do this in rails?

For example:

I have tag1 = Christmas, tag2 = Florida, tag3 = John

I want to find the Activity where tag1, tag2 and tag3 are present if it exists.

[EDIT]

What I ended up doing:

tags = [tag1, tag2, tag3]

activities = []
tags.each do |tag|
  activities << tag.activities
end

activities.flatten.group_by { |activity| activity.id }

If any of the groups values' size is equal to tags.size then that activity contains all tags.

Answer 1

If you want to have those activities where a particular tags should exist then try out teh following command

selected_activity = Activity.all.select do |activity|
                      %w(Christmas Florida John).all? do |name|
                        activity.tags.include?(name)
                      end 
                    end

Once it runs we can always refactor it so as to reduce the number of queries which are fired...

Answer 2

Not sure but this should be a better performant way to achieve it. But there should be an even better way

tags_ids = [tag1, tag2, tag3].map(&:id)
ativities_ids = Tagging.where(tag_id: tags_ids).group("activity_id having count(tag_id) = #{tags_ids.size}").select('activity_id').map(&:activity_id)
Activity.find(activities_id)

This will get activities that have those tags, but they can have others too.