Add Classifications and Resource validations

- Turn `has_and_belongs_to_many` into `has_many :through`: now,
resources and sections are related through Classifications.
- Refactor usage of jsonb column to use ActiveRecord validations
- Attention! store_accessor:

NOTE: If you are using structured database data types (eg. PostgreSQL hstore/json, or MySQL 5.7+ json) there is no need for the
serialization provided by .store. Simply use .store_accessor instead to generate the accessor methods. Be aware that these
columns use a string keyed hash and do not allow access using a symbol.

NOTE: The default validations with the exception of uniqueness will work. For example, if you want to check for uniqueness with
hstore you will need to use a custom validation to handle it.

https://api.rubyonrails.org/classes/ActiveRecord/Store.html

1 files changed, 3 insertions, 2 deletions

diff --git a/app/models/section.rb b/app/models/section.rb
index 6cfeb38..7d26882 100644
--- a/app/models/section.rb
+++ b/app/models/section.rb
@@ -1,11 +1,12 @@
 class Section < ApplicationRecord
   belongs_to :category
   has_one :taxonomy, through: :category
-  has_and_belongs_to_many :resources
+  has_many :classifications
+  has_many :resources, through: :classifications
 
   acts_as_list column: :rank, scope: :category
 
   validates :name,
             uniqueness: { scope: :category_id },
-            length: 3..64
+            length: { in: 3..64 }
 end