Refactor Collection concern to optimize database queries

[kanejamison]

Description

The Collection concern's load_collection and load_post methods make multiple database calls per request, including repeated PostType.find_by lookups that aren't cached. This creates unnecessary database load, especially for high-traffic collections.

Current code

lib/bunko/controllers/collection.rb:49-50:

@post_type = PostType.find_by(name: @collection_name)  # DB call #1
# ...
base_query = post_model.published.by_post_type(@collection_name)  # DB call #2 (joins post_types)

Problems this causes

1. Multiple database calls in a single action
2. PostType lookup happens on every request (these rarely change)
3. No guidance on N+1 prevention for associations
4. Unnecessary JOIN in by_post_type scope when we already have the PostType
5. Could be slow for high-traffic sites

Pros of refactoring

• Fewer database queries per request
• Better performance for high-traffic collections
• Lower database load
• Potential for significant speedup with caching
• Better example for users building on top of Bunko

Cons of refactoring

• Adds complexity with caching
• Need to handle cache invalidation
• May need configuration for cache strategy

Recommended approach

Option A - Cache PostType lookups:

def find_post_type(name)
  Rails.cache.fetch("bunko/post_type/#{name}", expires_in: 1.hour) do
    PostType.find_by(name: name)
  end
end

Option B - Use post_type_id once we have it:

@post_type = PostType.find_by(name: @collection_name)
base_query = post_model.published.where(post_type_id: @post_type.id)

Option C - Combine both approaches for maximum performance

Also consider adding documentation or helper methods for eager loading common associations to prevent N+1s.

References

• lib/bunko/controllers/collection.rb:49-50
• lib/bunko/controllers/collection.rb:92-98