[RailsConf 2023] Rails as a piece of cake

Transcript

1. Vladimir Dementyev
   Evil Martians
   RAILS AS A PIECE
   OF BIRTHDAY CAKE
   

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2. palkan_tula
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   2
   guides.rubyonrails.org
   

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3. palkan_tula
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   –Application Programming in
   Smalltalk-80 (TM), Steve Burbeck, 1987
   “In the MVC paradigm the user input, the
   modeling of the external world, and the visual
   feedback to the user are explicitly separated
   and handled by three types of object, each
   specialized for its task.”
   3
   

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4. The model class
   concerns itself only
   with the application's
   state and logic
   

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5. The view class
   concerns itself only
   with creating the user
   interface
   

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6. The controller class is
   occupied solely with
   translating user input
   into updates that it
   passes to the model
   

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7. palkan_tula
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   5
   Rails vs MVC
   Model
   View
   Controller
   

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8. palkan_tula
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   5
   Rails vs MVC
   Model
   View
   Controller
   

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9. palkan_tula
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   6
   Rails vs MVC
   View
   Controller
   Model
   

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10. palkan_tula
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    6
    Rails vs MVC
    View
    Controller
    Model
    Un-separation of
    concerns
    

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11. 7
    

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12. palkan_tula
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    8
    MVC cake
    

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13. palkan_tula
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    Mature MVC cake
    8
    

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14. palkan_tula
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    9
    Beyond MVC cake
    

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15. palkan_tula
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    10
    github.com/palkan
    

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16. palkan_tula
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    11
    github.com/palkan
    

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17. 12
    

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18. 13
    

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19. evilmartians.com/events
    

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20. Layers on Rails
    

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21. palkan_tula
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    16
    Rails Way
    Request
    Response
    

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22. palkan_tula
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    17
    Rails Way
    Model
    Controller View
    Request
    Response
    

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23. palkan_tula
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    18
    Extended Rails Way
    Model
    Controller View
    ?
    Request
    Response
    

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24. palkan_tula
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    19
    Maintainability
    Readability
    Testability
    Coupling
    Cohesion
    Extensibility
    Flexibility Complexity
    Reusability
    

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25. 20
    

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26. palkan_tula
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    21
    Bad abstractions Good abstractions
    

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27. Abstractions
    on Rails
    Railroad at Murnau, Wassily Kandinsky
    

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28. 23
    Abstraction layer for Rails cake
    

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29. palkan_tula
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    24
    Abstraction
    Generalization
    Encapsulation
    Loose Coupling
    Testability Centralization
    Simplification Single Responsibility
    Reusability
    

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30. palkan_tula
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    25
    Rails Abstraction
    Generalization
    Encapsulation
    Loose Coupling
    Testability Centralization
    Simplification
    Single Responsibility
    Reusability
    Conventions
    

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31. 26
    Abstraction layer for Rails cake
    1. Rails conventions Learn how Rails work, re-use
    patterns and building blocks.
    

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32. palkan_tula
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    27
    Layered Architecture
    Presentation
    Application
    Domain
    Infrastructure
    

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33. palkan_tula
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    28
    Layered Architecture
    Presentation
    Application
    Domain
    Infrastructure
    !
    

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34. 29
    

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35. palkan_tula
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    30
    Layered Architecture
    Presentation
    Application
    Domain
    Infrastructure
    

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36. palkan_tula
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    30
    Layered Architecture
    Presentation
    Application
    Domain
    Infrastructure
    

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37. Controllers
    Presentation
    Channels
    Views
    Application Jobs
    Mailers
    Domain
    Infrastructure
    Models
    Adapters (DB, mail)
    API clients
    

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38. palkan_tula
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    32
    class Authenticator
    def call(request)
    auth_header = request.headers["Authorization"]
    raise "Missing auth header" unless auth_header
    token = auth_header.split(" ").last
    raise "No token found" unless token
    JWT.decode(
    token,
    Rails.application.secrets.secret_key_base
    ).then do
    User.find(_1["user_id"]) if _1["user_id"]
    end
    end
    end
    Layer: ?
    

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39. palkan_tula
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    33
    class Authenticator
    def call(request)
    auth_header = request.headers["Authorization"]
    raise "Missing auth header" unless auth_header
    token = auth_header.split(" ").last
    raise "No token found" unless token
    JWT.decode(
    token,
    Rails.application.secrets.secret_key_base
    ).then do
    User.find(_1["user_id"]) if _1["user_id"]
    end
    end
    end
    Presentation
    Layer: Presentation
    

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40. palkan_tula
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    34
    class Authenticator
    def call(request)
    auth_header = request.headers["Authorization"]
    raise "Missing auth header" unless auth_header
    token = auth_header.split(" ").last
    raise "No token found" unless token
    JWT.decode(
    token,
    Rails.application.secrets.secret_key_base
    ).then do
    User.find(_1["user_id"]) if _1["user_id"]
    end
    end
    end
    Presentation
    Infrastructure
    Layer: Presentation ???
    

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41. palkan_tula
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    35
    class Authenticator
    def call(token)
    raise "No token found" unless token
    JWT.decode(
    token,
    Rails.application.secrets.secret_key_base
    ).then do
    User.find(_1["user_id"]) if _1["user_id"]
    end
    end
    end
    Layer: Application
    

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42. palkan_tula
    palkan
    An object belongs to the highest architecture
    layer among all its inputs and dependencies
    36
    

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43. 37
    Abstraction layer for Rails cake
    1. Rails conventions Learn how Rails work, re-use
    patterns and building blocks.
    2. Layered architecture ideas Identify the target arch. layer;
    avoid mixing too many layers.
    

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44. palkan_tula
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    How to choose new abstractions?
    38
    

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45. palkan_tula
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    How to choose new extract abstractions?
    39
    

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46. 40
    Abstraction layer for Rails cake
    1. Rails conventions Learn how Rails work, re-use
    patterns and building blocks.
    2. Layered architecture ideas Identify the target arch. layer;
    avoid mixing too many layers.
    3. Сodebase extracts, no
    artificial concepts
    Perform complexity analysis,
    analyze and extract abstractions.
    

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47. Extraction
    Time
    

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48. class GithooksController < ApplicationController
    def create
    event = JSON.parse(request.raw_post, symbolize_names: true)
    login = event.dig(:issue, :user, :login) ||
    event.dig(:pull_request, :user, :login)
    User.find_by(gh_id: login)
    &.handle_github_event(event) if login
    head :ok
    end
    end
    42
    Case #1: Models vs. webhooks
    

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49. class User < ApplicationRecord
    def handle_github_event(event)
    case event
    in type: "issue", action: "opened",
    issue: {user: {login:}, title:, body:}
    issues.create!(title:, body:)
    in type: "pull_request", action: "opened",
    pull_request: {
    user: {login:}, base: {label:}, title:, body:
    }
    pull_requests.create!(title:, body:, branch:)
    end
    end
    end
    43
    

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50. class User < ApplicationRecord
    def handle_github_event(event)
    case event
    in type: "issue", action: "opened",
    issue: {user: {login:}, title:, body:}
    issues.create!(title:, body:)
    in type: "pull_request", action: "opened",
    pull_request: {
    user: {login:}, base: {label:}, title:, body:
    }
    pull_requests.create!(title:, body:, branch:)
    end
    end
    end
    Hash originated in
    the outer world
    43
    

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51. class GitHubEvent
    def self.parse(raw_event)
    parsed = JSON.parse(raw_event, symbolize_names: true)
    case parsed[:type]
    when "issue"
    Issue.new(
    # ...
    )
    when "pull_request"
    PR.new(
    # ...
    )
    end
    rescue JSON::ParserError
    nil
    end
    Issue = Data.define(:user_id, :action, :title, :body)
    PR = Data.define(:user_id, :action, :title, :body, :branch)
    end
    44
    

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52. class GithooksController < ApplicationController
    def create
    event = GitHubEvent.parse(request.raw_post)
    User.find_by(gh_id: event.user_id)
    &.handle_github_event(event) if event
    head :ok
    end
    end
    45
    

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53. class User < ApplicationRecord
    def handle_github_event(event)
    case event
    in GitHubEvent::Issue[action: "opened", title:, body:]
    issues.create!(title:, body:)
    in GitHubEvent::PR[
    action: "opened", title:, body:, branch:
    ]
    pull_requests.create!(title:, body:, branch:)
    end
    end
    end
    46
    

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54. palkan_tula
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    Maintainability "
    — Controller: not ad-hoc hacks, less churn
    — Model: no knowledge of the outer world
    — Webhook payload access is encapsulated
    and localized
    47
    

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55. palkan_tula
    palkan
    Should a model be responsible for handling
    webhooks at all?
    48
    

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56. 49
    

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57. Controllers
    Presentation
    Channels
    Views
    Application Jobs
    Mailers
    Domain
    Infrastructure
    Models
    Adapters (DB, mail)
    API clients
    

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58. Controllers
    Presentation
    Channels
    Views
    Application Jobs
    Mailers
    Domain
    Infrastructure
    Models
    Adapters (DB, mail)
    Service Objects
    

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59. palkan_tula
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    Service Objects
    — Pseudo abstraction layer (generalization,
    consistency)
    51
    

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60. palkan_tula
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    Service Objects
    — Pseudo abstraction layer (generalization,
    consistency)
    — "app/services"—bag of random objects
    51
    

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61. palkan_tula
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    Service Objects
    — Pseudo abstraction layer (generalization,
    consistency)
    — "app/services"—bag of random objects
    —Intermediate stage until the final
    abstraction emerges
    51
    

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62. palkan_tula
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    52
    Service objects ~ waiting room
    sms_sender.rb
    rss_service.rb
    remind_user.rb
    auth_service.rb post/publish.rb
    

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63. palkan_tula
    palkan
    To "app/services" or not to
    "app/services"?
    — Don't start early with abstractions →
    better generalization requires a bit of
    aging
    — Don't overcrowd "app/services"
    53
    

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64. class GithooksController < ApplicationController
    def create
    event = GitHubEvent.parse(request.raw_post)
    GithubEventHandler.call(event) if event
    head :ok
    end
    end
    54
    

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65. class GithubEventHandler
    def self.call(event)
    user = User.find_by(gh_id: event.user_id)
    return false unless user
    case event
    in GitHubEvent::Issue[action: "opened", title:, body:]
    user.issues.create!(title:, body:)
    in GitHubEvent::PR[
    action: "opened", title:, body:, branch:
    ]
    user.pull_requests.create!(title:, body:, branch:)
    else
    # ignore unknown events
    end
    true
    end
    end
    55
    

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66. 56
    

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67. palkan_tula
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    57
    Case #2: Models vs. forms
    

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68. 58
    class User < ApplicationRecord
    attribute :should_send_invitation, :boolean
    after_commit :send_invitation, if: :should_send_invitation,
    on: :create
    def send_invitation
    UserMailer.invite(self).deliver_later
    end
    end
    

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69. 59
    class User < ApplicationRecord
    attribute :should_send_invitation, :boolean
    after_commit :send_invitation, if: :should_send_invitation,
    on: :create
    def send_invitation
    UserMailer.invite(self).deliver_later
    end
    end
    Layered Arch: Sending emails from models? Is it even legal #
    

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70. 60
    class User < ApplicationRecord
    attribute :should_send_invitation, :boolean
    after_commit :send_invitation, if: :should_send_invitation,
    on: :create
    def send_invitation
    UserMailer.invite(self).deliver_later
    end
    end
    Layered Arch: Sending emails from models? Is it even legal #
    Context-specific information now a part of the domain model
    

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71. 61
    class User < ApplicationRecord
    attribute :should_send_invitation, :boolean
    after_commit :send_invitation, if: :should_send_invitation,
    on: :create
    def send_invitation
    UserMailer.invite(self).deliver_later
    end
    end
    >= Application Layer
    

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72. class InvitationsController < ApplicationController
    def create
    @user = User.new(params.require(:user).permit(:email))
    @user.should_send_invitation = true
    if @user.save
    if params[:send_copy] == "1"
    UserMailer.invite_copy(current_user, @user)
    .deliver_later
    end
    redirect_to root_path, notice: "Invited!"
    else
    render :new
    end
    end
    end
    62
    

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73. class InvitationsController < ApplicationController
    def create
    @user = User.new(params.require(:user).permit(:email))
    @user.should_send_invitation = true
    if @user.save
    if params[:send_copy] == "1"
    UserMailer.invite_copy(current_user, @user)
    .deliver_later
    end
    redirect_to root_path, notice: "Invited!"
    else
    render :new
    end
    end
    end
    63
    Leaking abstraction $
    

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74. palkan_tula
    palkan
    Where can we localize
    the invitation form logic?
    64
    

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75. Jobs
    Service Objects
    Application
    Mailers
    Domain
    Infrastructure
    Models
    DB / API / etc
    Controllers
    Presentation
    Channels
    Views
    

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76. Jobs
    Service Objects
    Application
    Mailers
    Domain Models
    Form objects
    Controllers
    Presentation
    Channels
    Views
    

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77. class UserInvitationForm
    attr_reader :user, :send_copy, :sender
    def initialize(email, send_copy: false, sender: nil)
    @user = User.new(email:)
    @send_copy = send_copy.in?(%w[1 t true])
    @sender = sender
    end
    def save
    return false unless user.valid?
    user.save!
    deliver_notifications!
    true
    end
    def deliver_notifications!
    UserMailer.invite(user).deliver_later
    if send_copy
    UserMailer.invite_copy(sender, user).deliver_later
    end
    end
    end
    

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78. class UserInvitationForm
    attr_reader :user, :send_copy, :sender
    def initialize(email, send_copy: false, sender: nil)
    @user = User.new(email:)
    @send_copy = send_copy.in?(%w[1 t true])
    @sender = sender
    end
    def save
    return false unless user.valid?
    user.save!
    deliver_notifications!
    true
    end
    def deliver_notifications!
    UserMailer.invite(user).deliver_later
    if send_copy
    UserMailer.invite_copy(sender, user).deliver_later
    end
    end
    end
    Manual type-casting
    

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79. palkan_tula
    palkan
    class InvitationsController < ApplicationController
    def create
    form = UserInvitationForm.new(
    params.require(:user).permit(:email)[:email],
    params[:send_copy],
    current_user
    )
    if form.save
    redirect_to root_path, notice: "Invited!"
    else
    @user = form.user
    render :new
    end
    end
    end
    68
    

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80. class InvitationsController < ApplicationController
    def create
    form = UserInvitationForm.new(
    params.require(:user).permit(:email)[:email],
    params[:send_copy],
    current_user
    )
    if form.save
    redirect_to root_path, notice: "Invited!"
    else
    @user = form.user
    render :new
    end
    end
    end
    69
    Two sets of params
    Hack to re-use templates +
    leaking internals
    

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81. class InvitationsController < ApplicationController
    def create
    form = UserInvitationForm.new(
    params.require(:user).permit(:email)[:email],
    params[:send_copy],
    current_user
    )
    if form.save
    redirect_to root_path, notice: "Invited!"
    else
    @user = form.user
    render :new
    end
    end
    end
    70
    Two sets of params
    Hack to re-use templates +
    leaking internals
    

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82. palkan_tula
    palkan
    — Type casting, validations
    — Trigger side actions on successful
    submission
    — Compatibility with the view layer
    71
    Form object → Rails abstraction
    

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83. palkan_tula
    palkan
    Form object → Rails abstraction
    — Type casting, validations → ActiveModel::API
    + ActiveModel::Attributes
    — Trigger side actions on successful
    submission → ActiveSupport::Callbacks
    — Compatibility with the view layer →
    ActiveModel::Name + conventions
    72
    

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84. class InvitationForm < ApplicationForm
    attribute :email
    attribute :send_copy, :boolean
    attr_accessor :sender
    validates :email, presence: true
    after_commit :deliver_invitation
    after_commit :deliver_invitation_copy, if: :send_copy
    def submit!
    @user = User.new(email:)
    @user.save!
    end
    def deliver_invitation
    UserMailer.invite(@user).deliver_later
    end
    def deliver_invitation_copy
    UserMailer.invite_copy(sender, @user).deliver_later if sender
    end
    end
    

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85. class InvitationForm < ApplicationForm
    attribute :email
    attribute :send_copy, :boolean
    attr_accessor :sender
    validates :email, presence: true
    after_commit :deliver_invitation
    after_commit :deliver_invitation_copy, if: :send_copy
    def submit!
    @user = User.new(email:)
    @user.save!
    end
    def deliver_invitation
    UserMailer.invite(@user).deliver_later
    end
    def deliver_invitation_copy
    UserMailer.invite_copy(sender, @user).deliver_later if sender
    end
    end
    Form fields (w/types)
    

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86. class InvitationForm < ApplicationForm
    attribute :email
    attribute :send_copy, :boolean
    attr_accessor :sender
    validates :email, presence: true
    after_commit :deliver_invitation
    after_commit :deliver_invitation_copy, if: :send_copy
    def submit!
    @user = User.new(email:)
    @user.save!
    end
    def deliver_invitation
    UserMailer.invite(@user).deliver_later
    end
    def deliver_invitation_copy
    UserMailer.invite_copy(sender, @user).deliver_later if sender
    end
    end
    Form fields (w/types)
    Core logic
    

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87. class InvitationForm < ApplicationForm
    attribute :email
    attribute :send_copy, :boolean
    attr_accessor :sender
    validates :email, presence: true
    after_commit :deliver_invitation
    after_commit :deliver_invitation_copy, if: :send_copy
    def submit!
    @user = User.new(email:)
    @user.save!
    end
    def deliver_invitation
    UserMailer.invite(@user).deliver_later
    end
    def deliver_invitation_copy
    UserMailer.invite_copy(sender, @user).deliver_later if sender
    end
    end
    Form fields (w/types)
    Core logic
    Trigger actions
    

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88. palkan_tula
    palkan
    74
    class InvitationsController < ApplicationController
    def new
    @invitation_form = InvitationForm.new
    end
    def create
    @invitation_form = InvitationForm.new(
    params.require(:invitation).permit(:email, :send_copy)
    )
    @invitation_form.sender = current_user
    if @invitation_form.save
    redirect_to root_path
    else
    render :new, status: :unprocessable_entity
    end
    end
    end
    

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89. palkan_tula
    palkan
    75
    <%= form_for(@invitation_form) do |form| %>
    <%= form.label :email %>
    <%= form.text_field :email %>
    <%= form.label :send_copy, "Send me the copy" %>
    <%= form.check_box :send_copy %>
    <%= form.submit "Invite" %>
    <% end %>
    
    

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90. class ApplicationForm
    include ActiveModel::API
    include ActiveModel::Attributes
    define_callbacks :save, only: :after
    define_callbacks :commit, only: :after
    def save
    return false unless valid?
    with_transaction do
    AfterCommitEverywhere.after_commit { run_callbacks(:commit) }
    run_callbacks(:save) { submit! }
    end
    end
    def model_name
    ActiveModel::Name.new(nil, nil, self.class.name.sub(/Form$/, ""))
    end
    private
    def with_transaction(&) = ApplicationRecord.transaction(&)
    def submit!
    raise NotImplementedError
    end
    end
    

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91. class ApplicationForm
    include ActiveModel::API
    include ActiveModel::Attributes
    define_callbacks :save, only: :after
    define_callbacks :commit, only: :after
    def save
    return false unless valid?
    with_transaction do
    AfterCommitEverywhere.after_commit { run_callbacks(:commit) }
    run_callbacks(:save) { submit! }
    end
    end
    def model_name
    ActiveModel::Name.new(nil, nil, self.class.name.sub(/Form$/, ""))
    end
    private
    def with_transaction(&) = ApplicationRecord.transaction(&)
    def submit!
    raise NotImplementedError
    end
    end
    Types and validations
    

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92. class ApplicationForm
    include ActiveModel::API
    include ActiveModel::Attributes
    define_callbacks :save, only: :after
    define_callbacks :commit, only: :after
    def save
    return false unless valid?
    with_transaction do
    AfterCommitEverywhere.after_commit { run_callbacks(:commit) }
    run_callbacks(:save) { submit! }
    end
    end
    def model_name
    ActiveModel::Name.new(nil, nil, self.class.name.sub(/Form$/, ""))
    end
    private
    def with_transaction(&) = ApplicationRecord.transaction(&)
    def submit!
    raise NotImplementedError
    end
    end
    Types and validations
    Callbacks
    

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93. class ApplicationForm
    include ActiveModel::API
    include ActiveModel::Attributes
    define_callbacks :save, only: :after
    define_callbacks :commit, only: :after
    def save
    return false unless valid?
    with_transaction do
    AfterCommitEverywhere.after_commit { run_callbacks(:commit) }
    run_callbacks(:save) { submit! }
    end
    end
    def model_name
    ActiveModel::Name.new(nil, nil, self.class.name.sub(/Form$/, ""))
    end
    private
    def with_transaction(&) = ApplicationRecord.transaction(&)
    def submit!
    raise NotImplementedError
    end
    end
    Types and validations
    Callbacks
    Transaction-awareness
    

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94. class ApplicationForm
    include ActiveModel::API
    include ActiveModel::Attributes
    define_callbacks :save, only: :after
    define_callbacks :commit, only: :after
    def save
    return false unless valid?
    with_transaction do
    AfterCommitEverywhere.after_commit { run_callbacks(:commit) }
    run_callbacks(:save) { submit! }
    end
    end
    def model_name
    ActiveModel::Name.new(nil, nil, self.class.name.sub(/Form$/, ""))
    end
    private
    def with_transaction(&) = ApplicationRecord.transaction(&)
    def submit!
    raise NotImplementedError
    end
    end
    Types and validations
    Callbacks
    Transaction-awareness
    Action View compatibility
    (InvitationForm → /invitations)
    

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95. class ApplicationForm
    include ActiveModel::API
    include ActiveModel::Attributes
    define_callbacks :save, only: :after
    define_callbacks :commit, only: :after
    def save
    return false unless valid?
    with_transaction do
    AfterCommitEverywhere.after_commit { run_callbacks(:commit) }
    run_callbacks(:save) { submit! }
    end
    end
    def model_name
    ActiveModel::Name.new(nil, nil, self.class.name.sub(/Form$/, ""))
    end
    private
    def with_transaction(&) = ApplicationRecord.transaction(&)
    def submit!
    raise NotImplementedError
    end
    end
    Types and validations
    Callbacks
    Transaction-awareness
    Action View compatibility
    (InvitationForm → /invitations)
    Interface
    

    View Slide

96. class ApplicationForm
    include ActiveModel::API
    include ActiveModel::Attributes
    define_callbacks :save, only: :after
    define_callbacks :commit, only: :after
    def save
    return false unless valid?
    with_transaction do
    AfterCommitEverywhere.after_commit { run_callbacks(:commit) }
    run_callbacks(:save) { submit! }
    end
    end
    def model_name
    ActiveModel::Name.new(nil, nil, self.class.name.sub(/Form$/, ""))
    end
    private
    def with_transaction(&) = ApplicationRecord.transaction(&)
    def submit!
    raise NotImplementedError
    end
    end
    Types and validations
    Callbacks
    Transaction-awareness
    Action View compatibility
    Interface
    

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97. palkan_tula
    palkan
    — Type casting, validations ✅
    — Trigger side actions on successful submission ✅
    — Compatibility with the view layer ✅
    — Strong parameters compatibility
    — DX (test matchers, generators)
    78
    Form object → Rails abstraction
    

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98. 79
    Abstraction layer for Rails cake
    1. Rails conventions Learn how Rails work, re-use
    patterns and building blocks.
    2. Layered architecture ideas Identify the target arch. layer;
    avoid mixing too many layers.
    3. Сodebase extracts, no
    artificial concepts
    Perform complexity analysis,
    analyze and extract abstractions.
    

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99. 79
    Abstraction layer for Rails cake
    1. Rails conventions Learn how Rails work, re-use
    patterns and building blocks.
    2. Layered architecture ideas Identify the target arch. layer;
    avoid mixing too many layers.
    3. Сodebase extracts, no
    artificial concepts
    Perform complexity analysis,
    analyze and extract abstractions.
    Feel free to experiment and add ingredients from other
    paradigms and ecosystems!
    

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100. palkan_tula
     palkan
     How many layers is enough?
     80
     

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101. Controllers
     Channels
     Presentation
     Views
     Application
     Jobs
     Presenters
     Form objects
     Filter objects
     Deliveries
     Authorization Policies
     Event Listeners
     Interactors
     

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102. Mailers
     Domain
     Infrastructure
     Models
     Adapters (DB, mail)
     API clients
     Deliveries
     Notifiers
     Interactors
     Query objects
     Configuration objects
     Value objects
     Service objects
     

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103. 84
     

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104. The Book
     Coming Oct 2023
     

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105. @palkan
     @palkan_tula
     evilmartians.com
     @evilmartians
     Thanks!
     

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