model-patterns

Name: model-patterns
Author: ThibautBaissac

635stars79forks

How to install model-patterns?

thibautbaissac/rails_ai_agents/model-patterns

$npx -y skills add ThibautBaissac/rails_ai_agents --skill model-patterns

Installs into the current project.

Summary

Builds rich domain models with business logic, concerns, and proper associations following the fat-models-over-service-objects philosophy. Use when creating models, adding validations, scopes, callbacks, business logic methods, or associations. WHEN NOT: Controller/routing work (

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SKILL.md

1	# Model Patterns (37signals)
2
3	Rich domain models over service objects. Business logic lives in models, not in separate service classes.
4
5	## Project knowledge
6
7	Tech Stack: Rails 8.2 (edge), UUIDs everywhere, database-backed everything (no Redis)
8	Patterns: Heavy use of concerns, default values via lambdas, Current for context
9
10	Commands:
11	```bash
12	bin/rails generate model Card title:string body:text board:references:uuid
13	bin/rails generate migration AddColorToCards color:string
14	bin/rails db:migrate
15	bin/rails test test/models/
16	bin/rails console
17	```
18
19	## Rich model vs service object
20
21	```ruby
22	# BAD -- service object
23	class CloseCardService
24	def initialize(card, user)
25	@card = card
26	@user = user
27	end
28
29	def call
30	ActiveRecord::Base.transaction do
31	@card.create_closure!(user: @user)
32	@card.track_event("card_closed", user: @user)
33	end
34	end
35	end
36
37	# GOOD -- rich model
38	class Card < ApplicationRecord
39	include Closeable
40
41	def close(user: Current.user)
42	create_closure!(user: user)
43	track_event "card_closed", user: user
44	notify_recipients_later
45	end
46	end
47
48	# Controller simply calls:
49	@card.close
50	```
51
52	## Model structure
53
54	Order within a model:
55
56	```ruby
57	class Card < ApplicationRecord
58	# 1. Concern includes
59	include Assignable, Closeable, Eventable, Searchable, Watchable
60
61	# 2. Associations
62	belongs_to :account, default: -> { board.account }
63	belongs_to :board, touch: true
64	belongs_to :column, touch: true
65	belongs_to :creator, class_name: "User", default: -> { Current.user }
66
67	has_many :comments, dependent: :destroy
68	has_many :assignments, dependent: :destroy
69	has_one :closure, dependent: :destroy
70
71	# 3. Validations
72	validates :title, presence: true
73	validates :status, inclusion: { in: %w[draft published archived] }
74
75	# 4. Enums
76	enum :status, { draft: "draft", published: "published", archived: "archived" }, default: :draft
77
78	# 5. Scopes
79	scope :recent, -> { order(created_at: :desc) }
80	scope :positioned, -> { order(:position) }
81	scope :active, -> { open.published.where.missing(:not_now) }
82
83	# 6. Delegations
84	delegate :name, to: :board, prefix: true, allow_nil: true
85
86	# 7. Callbacks (sparingly)
87	after_create_commit :broadcast_creation
88
89	# 8. Business logic methods
90	def publish
91	update!(status: :published)
92	track_event "card_published"
93	end
94
95	def move_to_column(new_column)
96	update!(column: new_column)
97	track_event "card_moved", particulars: {
98	from_column_id: column_id_before_last_save,
99	to_column_id: new_column.id
100	}
101	end
102
103	private
104
105	def broadcast_creation
106	broadcast_prepend_to board, :cards, target: "cards", partial: "cards/card"
107	end
108	end
109	```
110
111	## Association patterns
112
113	### belongs_to with defaults
114
115	```ruby
116	belongs_to :account, default: -> { board.account }
117	belongs_to :creator, class_name: "User", default: -> { Current.user }
118	belongs_to :board, touch: true # Updates parent's updated_at
119	```
120
121	### has_many / has_one
122
123	```ruby
124	has_many :comments, dependent: :destroy
125	has_many :assignees, through: :assignments, source: :assignee
126	has_one :closure, dependent: :destroy
127	```
128
129	### Polymorphic
130
131	```ruby
132	has_many :attachments, as: :attachable, dependent: :destroy
133	has_many :events, as: :eventable, dependent: :destroy
134	belongs_to :notifiable, polymorphic: true
135	```
136
137	### Counter caches
138
139	```ruby
140	belongs_to :card, counter_cache: :comments_count
141	belongs_to :board, counter_cache: :cards_count
142	```
143
144	## Scope patterns
145
146	```ruby
147	# Basic ordering
148	scope :recent, -> { order(created_at: :desc) }
149	scope :positioned, -> { order(:position) }
150
151	# With arguments
152	scope :by_creator, ->(user) { where(creator: user) }
153	scope :created_after, ->(date) { where("created_at > ?", date) }
154
155	# Joins and where.missing (key pattern for state records)
156	scope :assigned_to, ->(users) { joins(:assignments).where(assignments: { assignee: users }).distinct }
157	scope :open, -> { where.missing(:closure) }
158	scope :unassigned, -> { where.missing(:assignments) }
159
160	# Complex composed scopes
161	scope :entropic, -> {
162	open.published.where.missing(:not_now).where("updated_at < ?", 30.days.ago)
163	}
164	```
165
166	## Validation patterns
167
168	```ruby
169	validates :title, presence: true
170	validates :email, format: { with: URI::MailTo::EMAIL_REGEXP }
171	validates :email_address, uniqueness: { case_sensitive: false }
172	validates :user_id, uniqueness: { scope: :card_id } # Join tables
173	validates :card, uniqueness: true # has_one state records
174	validates :body, presence: true, if: :published? # Conditional
175	```
176
177	## Call

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Type

model-patterns

635stars79forks

View on GitHub

How to install model-patterns?

thibautbaissac/rails_ai_agents/model-patterns

$npx -y skills add ThibautBaissac/rails_ai_agents --skill model-patterns

Installs into the current project.

Summary

Files · 1

View on GitHub

SKILL.md

1	# Model Patterns (37signals)
2
3	Rich domain models over service objects. Business logic lives in models, not in separate service classes.
4
5	## Project knowledge
6
7	Tech Stack: Rails 8.2 (edge), UUIDs everywhere, database-backed everything (no Redis)
8	Patterns: Heavy use of concerns, default values via lambdas, Current for context
9
10	Commands:
11	```bash
12	bin/rails generate model Card title:string body:text board:references:uuid
13	bin/rails generate migration AddColorToCards color:string
14	bin/rails db:migrate
15	bin/rails test test/models/
16	bin/rails console
17	```
18
19	## Rich model vs service object
20
21	```ruby
22	# BAD -- service object
23	class CloseCardService
24	def initialize(card, user)
25	@card = card
26	@user = user
27	end
28
29	def call
30	ActiveRecord::Base.transaction do
31	@card.create_closure!(user: @user)
32	@card.track_event("card_closed", user: @user)
33	end
34	end
35	end
36
37	# GOOD -- rich model
38	class Card < ApplicationRecord
39	include Closeable
40
41	def close(user: Current.user)
42	create_closure!(user: user)
43	track_event "card_closed", user: user
44	notify_recipients_later
45	end
46	end
47
48	# Controller simply calls:
49	@card.close
50	```
51
52	## Model structure
53
54	Order within a model:
55
56	```ruby
57	class Card < ApplicationRecord
58	# 1. Concern includes
59	include Assignable, Closeable, Eventable, Searchable, Watchable
60
61	# 2. Associations
62	belongs_to :account, default: -> { board.account }
63	belongs_to :board, touch: true
64	belongs_to :column, touch: true
65	belongs_to :creator, class_name: "User", default: -> { Current.user }
66
67	has_many :comments, dependent: :destroy
68	has_many :assignments, dependent: :destroy
69	has_one :closure, dependent: :destroy
70
71	# 3. Validations
72	validates :title, presence: true
73	validates :status, inclusion: { in: %w[draft published archived] }
74
75	# 4. Enums
76	enum :status, { draft: "draft", published: "published", archived: "archived" }, default: :draft
77
78	# 5. Scopes
79	scope :recent, -> { order(created_at: :desc) }
80	scope :positioned, -> { order(:position) }
81	scope :active, -> { open.published.where.missing(:not_now) }
82
83	# 6. Delegations
84	delegate :name, to: :board, prefix: true, allow_nil: true
85
86	# 7. Callbacks (sparingly)
87	after_create_commit :broadcast_creation
88
89	# 8. Business logic methods
90	def publish
91	update!(status: :published)
92	track_event "card_published"
93	end
94
95	def move_to_column(new_column)
96	update!(column: new_column)
97	track_event "card_moved", particulars: {
98	from_column_id: column_id_before_last_save,
99	to_column_id: new_column.id
100	}
101	end
102
103	private
104
105	def broadcast_creation
106	broadcast_prepend_to board, :cards, target: "cards", partial: "cards/card"
107	end
108	end
109	```
110
111	## Association patterns
112
113	### belongs_to with defaults
114
115	```ruby
116	belongs_to :account, default: -> { board.account }
117	belongs_to :creator, class_name: "User", default: -> { Current.user }
118	belongs_to :board, touch: true # Updates parent's updated_at
119	```
120
121	### has_many / has_one
122
123	```ruby
124	has_many :comments, dependent: :destroy
125	has_many :assignees, through: :assignments, source: :assignee
126	has_one :closure, dependent: :destroy
127	```
128
129	### Polymorphic
130
131	```ruby
132	has_many :attachments, as: :attachable, dependent: :destroy
133	has_many :events, as: :eventable, dependent: :destroy
134	belongs_to :notifiable, polymorphic: true
135	```
136
137	### Counter caches
138
139	```ruby
140	belongs_to :card, counter_cache: :comments_count
141	belongs_to :board, counter_cache: :cards_count
142	```
143
144	## Scope patterns
145
146	```ruby
147	# Basic ordering
148	scope :recent, -> { order(created_at: :desc) }
149	scope :positioned, -> { order(:position) }
150
151	# With arguments
152	scope :by_creator, ->(user) { where(creator: user) }
153	scope :created_after, ->(date) { where("created_at > ?", date) }
154
155	# Joins and where.missing (key pattern for state records)
156	scope :assigned_to, ->(users) { joins(:assignments).where(assignments: { assignee: users }).distinct }
157	scope :open, -> { where.missing(:closure) }
158	scope :unassigned, -> { where.missing(:assignments) }
159
160	# Complex composed scopes
161	scope :entropic, -> {
162	open.published.where.missing(:not_now).where("updated_at < ?", 30.days.ago)
163	}
164	```
165
166	## Validation patterns
167
168	```ruby
169	validates :title, presence: true
170	validates :email, format: { with: URI::MailTo::EMAIL_REGEXP }
171	validates :email_address, uniqueness: { case_sensitive: false }
172	validates :user_id, uniqueness: { scope: :card_id } # Join tables
173	validates :card, uniqueness: true # has_one state records
174	validates :body, presence: true, if: :published? # Conditional
175	```
176
177	## Call

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