Rails - How to refresh an association after a save

Question

I have a category with a list of items. The items have a position and the category has a relationship has_many :items, :order => "position". When a user updates a position value, I want to see its position. My position is a float to allow moving between rounded numbers.

pos=item.category.items.map(&:id) current_position=pos.index(id.to_i) item.save # want to refresh the relationship here pos_new=item.categoty.items.map(&:id) # grabbing this since just accessing item isn't updated if positioning has changed item_new=Item.find(id) pos_new=item_new.category.items.map(&:id) new_position=pos_new.index(id) if current_position!=new_position   is_moved=true # sent back in JSON to propagate a dynamic change. end 

The above works but it seems really verbose. Is there a way for me to tell on item save that the category relationship needs to be refreshed since the order could be changed?

Answer 1

For single-item associations:

book.reload_author 

For other associations:

author.books.reload 

http://guides.rubyonrails.org/association_basics.html#controlling-caching

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In older versions of rails, before Rails 5, you could pass true to an association method as the first parameter to make it reload: author.books(true).