[Rails] How to search across columns of related models (parent or child) in ransack

What you want to achieve

I want to search even the columns of the model related (nested) to one model

Specifically, I would like to search not only the store name of the used clothing store but also the area name (one-to-many) and the brand name (many-to-many).

Conclusion

** Specify related model name_related model column name as the element name of the form tag **

The related model is to 1 (belongs_to: hoge, and has_one: fuga)

For example, when you want to use the area name of the area model associated with the shop model as a search condition. = f. Form helper: Let element name of element name be ʻarea_name_cont`.

When disassembled area → Related model name name → Column name of the related model cont → Predicate that specifies a partial match

It will be.

= search_form_for(@q, url: shop_search_path) do |f|
  = f.text_field :area_name_cont
  #Area name of the area model associated with the shop model(name)

Related models are to many (has_many: hoges, etc.)

For example, when you want to use the brand name of the brands model associated with the shop model as a search condition. = f. Form helper: Let element name of element name be brands_name_cont.

When disassembled brands → Related model name * shop has_many: brands, so plural name → Column name of the related model cont → Predicate that specifies a partial match

It will be.

= search_form_for(@q, url: shop_search_path) do |f|
  = f.text_field :brands_name_or_genres_name_cont
  #Brand name of the brand model associated with the shop model(name)
  #The genre name of the genre model associated with the shop model(name)
  #* Note that when there are multiple linked models, the model name will be plural.

By the way, you can search multiple columns by connecting column names with _or_ etc.

For the actual usage of ransack, please refer to articles such as [Rails] Summary of various search form creation methods using ransack.

Association between models

• Only relevant parts are listed

shop.rb

#shop model
  belongs_to :area, optional: true
  has_many :shop_genres
  has_many :shop_brands
  has_many :genres, through: :shop_genres
  has_many :brands, through: :shop_brands

area.rb

#area model
  has_many :shops

brand.rb

#brand model
  has_many :shop_brands
  has_many :shops, through: :shop_brands

shop_brand.rb

# shop_brand model
  belongs_to :shop
  belongs_to :brand

shop_genre.rb

# shop_genre model
  belongs_to :shop
  belongs_to :genre

How to find out the association

It is convenient to use a method called ransackable_associations.

** 1. Rails c ** in the application directory

terminal

#Run in the appropriate application directory

$ rails c
Running via Spring preloader in process 61541
Loading development environment (Rails 5.0.7.2)
[1] pry(main)> 

** 2. Execute model name.ransackable_associations **

terminal

#This time I want to investigate the relationship with the Shop model, so Shop.ransackable_If you say associations
The model associated with the Shop model is displayed
[1] pry(main)> Shop.ransackable_associations
=> ["user", "area", "shop_genres", "shop_brands", "genres", "brands"]
[2] pry(main)> 

reference

[73 recipes to easily create a search form with Ransack -026 related](http://nekorails.hatenablog.com/entry/2017/05/31/173925#026-%E9%96%A2%E9%80% A3) How to search multiple columns in parent table and child table with Ransack