Is this caching correct in Rails?

Question

Ruby on Rails

I'm trying to cache through the standard gem - cache_digest, but the application still creates queries to the database:

- cache @bgroups do
            - @bgroups.each do |bgroup|
              .bgroup
                = link_to bgroup.name, bgroup_vacancy_path(bgroup)

Console:

Bgroup Load (0.3ms) SELECT "bgroups".* FROM "bgroups" LIMIT 20
Cache digest for app/views/home/index.html.haml: f62c6ca48d18920cf265aa17882d6e1a
Read fragment views/bgroups/1/bgroups/2/bgroups/3/ bgroups/4/bgroups/5/bgroups/6/bgroups/7/bgroups/8/bgroups/9/bgroups/10/bgroups/11/bgroups/12/bgroups/13/bgroups/14/bgroups/15/bgroups/ 16/bgroups/17/bgroups/18/bgroups/19/bgroups/20/f62c6ca48d18920cf265aa17882d6e1a (0.0ms)

As far as I understand, there should not be a request to the database at all if the information in the database has not changed, otherwise what is the point of such caching? What is the error then?

Answer 1

1) you need to cache an object that has an updated_at method
2) caching is usually turned off in the development environment

- @bgroups.each do |bgroup|
  = cache bgroup do
    .bgroup
       = link_to bgroup.name, bgroup_vacancy_path(bgroup)