Decouple your models with form objects

Forms are a crucial part of every app and Rails has good defaults for building them—unless you need something complicated. Maybe you want a multi-step wizard? Or maybe you'd like to pluck attributes from any model? Validation becomes a pain point. So you introduce a state machine, or nest your models, or do some other calisthenic to get everything working. Thankfully there's a better way! This talk takes a complicated wizard and converts it into a few simple form objects—it's a deep dive on decoupling models and how you can leverage Trailblazer's Reform gem to make it even easier.

Transcript

1. FORM OBJECTS Decouple your models with
3. data model == form
4. data model == form accepts_nested_attributes_for
5. store data 
 in the session session[:user_attributes] = @user.all_the_attributes
7. state machine
8. nested models class Dog::BreedDetails < Dog
9. view > model VIEW MODEL
10. Let’s not do it!
11. Form Objects
12. F O R M O B J E C T 3 What is a 
 form object?
13. F O R M O B J E C T 3 What is a 
 form object? <%= form_for(@person) do |f| %> <%= f.input :name %> <%= f.button :submit, 'Submit' %> <% end %>
14. F O R M O B J E C T 3
15. F O R M O B J E C T 3
17. DATA MODEL Company Phone Address User Account name time_zone number address city state zip country_code first_name last_name subscription_type kind Form 1 - Nested Data
18. DATA MODEL Company Phone Address User Account name time_zone number address city state zip country_code first_name last_name subscription_type kind Form 2 - Custom Logic
19. DATA MODEL Company Phone Address User Account name time_zone number address city state zip country_code first_name last_name subscription_type kind Form 3 - Data Scatter
20. F O R M O B J E C T 3
88. F O R M O B J E C T 3
89. F O R M O B J E C T 3
98. F O R M O B J E C T 3
106. Prepopulators Populators
107. Prepopulators Populators called manually with .prepopulate! prepares the form for rendering can fill out fields in the form :new, :edit
108. Prepopulators Populators called manually with .prepopulate! called every time when you .validate prepares the form for rendering prepares the form for validating cares about matching the right data to the right model can fill out fields in the form :new, :edit :create, :update
113. DATA MODEL Company Phone Address User Account name time_zone number address city state zip country_code first_name last_name subscription_type kind Form 1 - Nested Data
116. F O R M O B J E C T 3
141. F O R M O B J E C T 3
143. DATA MODEL Company Phone Address User Account name time_zone number address city state zip country_code first_name last_name subscription_type kind Form 3 - Data Scatter
165. A D VA N TA G E S 4 Advantages
166. A D VA N TA G E S 4 Form 
 Objects ‣ Model agnostic ‣ Validation is context-specific ‣ RESTful ‣ Easy to test ‣ Easy to extend and modify ‣ Use when you need to
167. A D VA N TA G E S 4 Form 
 Objects ‣ Model agnostic ‣ Validation is context-specific ‣ RESTful ‣ Easy to test ‣ Easy to extend and modify ‣ Use when you need to
168. A D VA N TA G E S 4 Form 
 Objects ‣ Model agnostic ‣ Validation is context-specific ‣ RESTful ‣ Easy to test ‣ Easy to extend and modify ‣ Use when you need to
169. A D VA N TA G E S 4 Form 
 Objects ‣ Model agnostic ‣ Validation is context-specific ‣ RESTful ‣ Easy to test ‣ Easy to extend and modify ‣ Use when you need to
170. A D VA N TA G E S 4 Form 
 Objects ‣ Model agnostic ‣ Validation is context-specific ‣ RESTful ‣ Easy to test ‣ Easy to extend and modify ‣ Use when you need to
171. A D VA N TA G E S 4 Form 
 Objects ‣ Model agnostic ‣ Validation is context-specific ‣ RESTful ‣ Easy to test ‣ Easy to extend and modify ‣ Use when you need to
172. The end.
173. attributes H T T P S : / / F O R U M . U P C A S E . C O M / T / F O R M - O B J E C T S / 2 2 6 7 H T T P S : / / R O B O T S . T H O U G H T B O T. C O M / A C T I V E M O D E L - F O R M - O B J E C T S H T T P : / / C O N F R E A K S . T V / V I D E O S / R A I L S C O N F 2 0 1 4 - U LT R A - L I G H T- A N D - M A I N TA I N A B L E - R A I L S - W I Z A R D S H T T P : / / T R A I L B L A Z E R . T O H T T P : / / T R A I L B L A Z E R . T O / G E M S / R E F O R M H T T P : / / J E R O M E D A L B E RT. C O M / H O W- D H H - O R G A N I Z E S - H I S - R A I L S - C O N T R O L L E R S /
174. @andrewmarkle H T T P S : / / I N D U S T R I A L A G E N C Y. C A