Cache in production

Question

I'm currently testing the caches in my app (Dalli gem). And a weird thing is happening. I'm caching a list related with the current_user. But when I test the app with different account (with different browsers), the caches are mixed.

For example: I run an action which change the caches of User1 , and those caches are applied to the account of User2.

So I would like to know if this problem is happening only because I'm doing it on development on the same computer, or if I should improve my cache system ?

Note: I've skip the digest to make it work, I'm not really sure of their needs. So i'm not really sure if that can be the starting point of my problem.

I share my code if you want more details of what I'm doing.

My code :

User (model):

class User < ApplicationRecord
  has_many :users_group, dependent: :destroy
  has_many :groups, through: :users_group
  has_many :favorit_groups, dependent: :destroy
  has_many :fav_groups, through: :favorit_groups, class_name: "Group", source: :group

  def cached_favgroups
    Rails.cache.fetch([self, "fav_groups"]) {fav_groups.to_a}
  end

  def cached_groups
    Rails.cache.fetch([self, "groups"]) {groups.to_a}
  end

View (sidenav):

<li class="list_groups_favorit">
<% cache 'cache_groups_fav_all', skip_digest: true do %>
  <% current_user.cached_favgroups.each do |group| %>
    <% cache group, skip_digest: true do %>
      <%= render 'groups/group', group: group%>
    <% end %>
  <% end %>
<% end %>
</li>
<li class="list_groups">
<% cache 'cache_groups_all', skip_digest: true do %>
  <% current_user.cached_groups.each do |group| %>
    <% cache group, skip_digest: true do %>
      <%= render 'groups/group', group: group%>
    <% end %>
  <% end %>
<% end %>
</li>

GroupController :

def favorit
  FavoritGroup.where(group_id: @group.id).where(user_id: current_user.id).first_or_create
  # Cache 
  Rails.cache.delete(current_user.cache_key+"/fav_groups")
  Rails.cache.delete(current_user.cache_key+"/groups")
  expire_fragment('cache_groups_fav_all')
  expire_fragment('cache_groups_all')
  expire_fragment(@group)
  # Cache
  respond_to do |format|
    format.html { redirect_back }
    format.js { render 'groups/js/favorit' }
  end 
end 

def unfavorit
  FavoritGroup.where(group_id: @group.id).where(user_id: current_user.id).delete_all
  # Cache
  Rails.cache.delete(current_user.cache_key+"/fav_groups")
  Rails.cache.delete(current_user.cache_key+"/groups")
  expire_fragment('cache_groups_fav_all')
  expire_fragment('cache_groups_all')
  expire_fragment(@group)
  # Cache
  respond_to do |format|
    format.html { redirect_back }
    format.js { render 'groups/js/unfavorit' }
  end
end