In this chapter, we will learn about the counter_culture gem which is more
beneficial than the default counter cache, offered by Rails, in some scenarios.
We had already seen the advantage of using counter_cache when we added a
column to the dashboard for displaying the number of comments under each task.
Although counter_cache can come in handy, there can be situations where you
might want to leverage the potential of counter_cache but cannot quite do so
because of business logic constraints. Let us delve into such a scenario and
understand why counter_culture can be useful in these cases.
Counter culture as an alternative to counter cache
Assume that in the future you are going to add an option to "star" comments in
the granite application. Let us say that the user requirements want you to
display the count of starred comments for each task under a new column
Starred Comments in the Dashboard. Using the default counter cache would be
difficult in such a scenario since this feature requires you to enforce some
conditions over a column like comments_count. The condition in this case would
be to check whether the comment is starred or not.
In such situations, the counter_culture gem can be of great help. The
counter_culture gem can be a useful alternative to using the counter cache
column if you want more control over which columns are updated and when.
You can set up counter_culture by adding the below text to your gem file and
running bundle install.
Now after adding the functionality to "star" comments, add a new column to your
tasks table with the name starred_comments_count. You can run the necessary
migrations, to achieve the same, as we saw in the
chapter
introducing counter_cache.
After adding the column, you can modify the Comment model in
app/models/comment.rb as follows:
Now, the Task model will keep the counter cache in starred_comments_count
up-to-date. Only comments where comment.starred? returns true will affect the
starred_comments_count.
counter_culture provides us additional functionalities like conditional
counter cache, customized column name and dynamic column name among others.
However, it does add some extra complexity to your application, and you should
consider whether it is the right solution for your particular use case.
You can learn more about counter_culture gem in the
official docs.
This is an in-depth chapter and you do not need to commit any changes.