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rails--rails/activerecord/test/models/author.rb
eileencodes de6b4efa3e
Add option to skip joins for associations.
In a multiple database application, associations can't join across
databases. When set, this option tells Rails to make 2 or more queries
rather than using joins for associations.

Set the option on a has many through association:

```ruby
class Dog
  has_many :treats, through: :humans, disable_joins: true
  has_many :humans
end
```

Then instead of generating join SQL, two queries are used for `@dog.treats`:

```
SELECT "humans"."id" FROM "humans" WHERE "humans"."dog_id" = ?  [["dog_id", 1]]
SELECT "treats".* FROM "treats" WHERE "treats"."human_id" IN (?, ?, ?)  [["human_id", 1], ["human_id", 2], ["human_id", 3]]
```

This code is extracted from a gem we use internally at GitHub which
means the implementation here is used in production daily and isn't
experimental.

I often get the question "why can't Rails do this automatically" so I
figured I'd include the answer in the commit. Rails can't do this
automatically because associations are lazily loaded. `dog.treats` needs
to load `Dog`, then `Human` and then `Treats`. When `dog.treats` is
called Rails pre-generates the SQL that will be run and puts that
information into a reflection object. Because the SQL parts are pre-generated,
as soon as `dog.treats` is loaded it's too late to skip a join. The join
is already available on the object and that join is what's run to load
`treats` from `dog` through `humans`. I think the only way to avoid setting
an option on the association is to rewrite how and when the SQL is
generated for associations which is a large undertaking. Basically the
way that Active Record associations are designed, it is currently
impossible to have Rails figure out to not join (loading the association
will cause the join to occur, and that join will raise an error if the
models don't live in the same db).

The original implementation was written by me and Aaron. Lee helped port
over tests, and I refactored the extraction to better match Rails style.

Co-authored-by: Lee Quarella <leequarella@gmail.com>
Co-authored-by: Aaron Patterson <aaron@rubyonrails.org>
2021-04-19 11:17:31 -04:00

304 lines
14 KiB
Ruby

# frozen_string_literal: true
class Author < ActiveRecord::Base
has_many :posts
has_many :serialized_posts
has_one :post
has_many :very_special_comments, through: :posts
has_many :posts_with_comments, -> { includes(:comments) }, class_name: "Post"
has_many :popular_grouped_posts, -> { includes(:comments).group("type").having("SUM(legacy_comments_count) > 1").select("type") }, class_name: "Post"
has_many :posts_with_comments_sorted_by_comment_id, -> { includes(:comments).order("comments.id") }, class_name: "Post"
has_many :posts_sorted_by_id, -> { order(:id) }, class_name: "Post"
has_many :posts_sorted_by_id_limited, -> { order("posts.id").limit(1) }, class_name: "Post"
has_many :posts_with_categories, -> { includes(:categories) }, class_name: "Post"
has_many :posts_with_comments_and_categories, -> { includes(:comments, :categories).order("posts.id") }, class_name: "Post"
has_many :posts_with_special_categorizations, class_name: "PostWithSpecialCategorization"
has_one :post_about_thinking, -> { where("posts.title like '%thinking%'") }, class_name: "Post"
has_one :post_about_thinking_with_last_comment, -> { where("posts.title like '%thinking%'").includes(:last_comment) }, class_name: "Post"
has_many :comments, through: :posts do
def ratings
Rating.joins(:comment).merge(self)
end
end
has_many :comments_with_order, -> { ordered_by_post_id }, through: :posts, source: :comments
has_many :no_joins_comments, through: :posts, disable_joins: :true, source: :comments
has_many :comments_with_foreign_key, through: :posts, source: :comments, foreign_key: :post_id
has_many :no_joins_comments_with_foreign_key, through: :posts, disable_joins: :true, source: :comments, foreign_key: :post_id
has_many :members,
through: :comments_with_order,
source: :origin,
source_type: "Member"
has_many :no_joins_members,
through: :comments_with_order,
source: :origin,
source_type: "Member",
disable_joins: true
has_many :ordered_members,
-> { order(id: :desc) },
through: :comments_with_order,
source: :origin,
source_type: "Member"
has_many :no_joins_ordered_members,
-> { order(id: :desc) },
through: :comments_with_order,
source: :origin,
source_type: "Member",
disable_joins: true
has_many :ratings, through: :comments
has_many :good_ratings,
-> { where("ratings.value > 5") },
through: :comments,
source: :ratings
has_many :no_joins_ratings, through: :no_joins_comments, disable_joins: :true, source: :ratings
has_many :no_joins_good_ratings,
-> { where("ratings.value > 5") },
through: :comments,
source: :ratings,
disable_joins: true
has_many :comments_containing_the_letter_e, through: :posts, source: :comments
has_many :comments_with_order_and_conditions, -> { order("comments.body").where("comments.body like 'Thank%'") }, through: :posts, source: :comments
has_many :comments_with_include, -> { includes(:post).where(posts: { type: "Post" }) }, through: :posts, source: :comments
has_many :comments_for_first_author, -> { for_first_author }, through: :posts, source: :comments
has_many :first_posts
has_many :comments_on_first_posts, -> { order("posts.id desc, comments.id asc") }, through: :first_posts, source: :comments
has_one :first_post
has_one :comment_on_first_post, -> { order("posts.id desc, comments.id asc") }, through: :first_post, source: :comments
has_many :thinking_posts, -> { where(title: "So I was thinking") }, dependent: :delete_all, class_name: "Post"
has_many :welcome_posts, -> { where(title: "Welcome to the weblog") }, class_name: "Post"
has_many :welcome_posts_with_one_comment,
-> { where(title: "Welcome to the weblog").where(comments_count: 1) },
class_name: "Post"
has_many :welcome_posts_with_comments,
-> { where(title: "Welcome to the weblog").where("legacy_comments_count > 0") },
class_name: "Post"
has_many :comments_desc, -> { order("comments.id DESC") }, through: :posts_sorted_by_id, source: :comments
has_many :unordered_comments, -> { unscope(:order).distinct }, through: :posts_sorted_by_id_limited, source: :comments
has_many :funky_comments, through: :posts, source: :comments
has_many :ordered_uniq_comments, -> { distinct.order("comments.id") }, through: :posts, source: :comments
has_many :ordered_uniq_comments_desc, -> { distinct.order("comments.id DESC") }, through: :posts, source: :comments
has_many :readonly_comments, -> { readonly }, through: :posts, source: :comments
has_many :special_posts
has_many :special_post_comments, through: :special_posts, source: :comments
has_many :special_posts_with_default_scope, class_name: "SpecialPostWithDefaultScope"
has_many :sti_posts, class_name: "StiPost"
has_many :sti_post_comments, through: :sti_posts, source: :comments
has_many :special_nonexistent_posts, -> { where("posts.body = 'nonexistent'") }, class_name: "SpecialPost"
has_many :special_nonexistent_post_comments, -> { where("comments.post_id" => 0) }, through: :special_nonexistent_posts, source: :comments
has_many :nonexistent_comments, through: :posts
has_many :hello_posts, -> { where "posts.body = 'hello'" }, class_name: "Post"
has_many :hello_post_comments, through: :hello_posts, source: :comments
has_many :posts_with_no_comments, -> { where("comments.id" => nil).includes(:comments) }, class_name: "Post"
has_many :posts_with_no_comments_2, -> { left_joins(:comments).where("comments.id": nil) }, class_name: "Post"
has_many :hello_posts_with_hash_conditions, -> { where(body: "hello") }, class_name: "Post"
has_many :hello_post_comments_with_hash_conditions, through: :hello_posts_with_hash_conditions, source: :comments
has_many :other_posts, class_name: "Post"
has_many :posts_with_callbacks, class_name: "Post", before_add: :log_before_adding,
after_add: :log_after_adding,
before_remove: :log_before_removing,
after_remove: :log_after_removing
has_many :posts_with_thrown_callbacks, class_name: "Post", before_add: :throw_abort,
after_add: :ensure_not_called,
before_remove: :throw_abort,
after_remove: :ensure_not_called
has_many :posts_with_proc_callbacks, class_name: "Post",
before_add: Proc.new { |o, r| o.post_log << "before_adding#{r.id || '<new>'}" },
after_add: Proc.new { |o, r| o.post_log << "after_adding#{r.id || '<new>'}" },
before_remove: Proc.new { |o, r| o.post_log << "before_removing#{r.id}" },
after_remove: Proc.new { |o, r| o.post_log << "after_removing#{r.id}" }
has_many :posts_with_multiple_callbacks, class_name: "Post",
before_add: [:log_before_adding, Proc.new { |o, r| o.post_log << "before_adding_proc#{r.id || '<new>'}" }],
after_add: [:log_after_adding, Proc.new { |o, r| o.post_log << "after_adding_proc#{r.id || '<new>'}" }]
has_many :unchangeable_posts, class_name: "Post", before_add: :raise_exception, after_add: :log_after_adding
has_many :categorizations, -> { }
has_many :categories, through: :categorizations
has_many :named_categories, through: :categorizations
has_many :special_categorizations
has_many :special_categories, through: :special_categorizations, source: :category
has_one :special_category, through: :special_categorizations, source: :category
has_many :general_categorizations, -> { joins(:category).where("categories.name": "General") }, class_name: "Categorization"
has_many :general_posts, through: :general_categorizations, source: :post
has_many :special_categories_with_conditions, -> { where(categorizations: { special: true }) }, through: :categorizations, source: :category
has_many :nonspecial_categories_with_conditions, -> { where(categorizations: { special: false }) }, through: :categorizations, source: :category
has_many :categories_like_general, -> { where(name: "General") }, through: :categorizations, source: :category, class_name: "Category"
has_many :categorized_posts, through: :categorizations, source: :post
has_many :unique_categorized_posts, -> { distinct }, through: :categorizations, source: :post
has_many :nothings, through: :kateggorisatons, class_name: "Category"
has_many :author_favorites
has_many :favorite_authors, -> { order("name") }, through: :author_favorites
has_many :taggings, through: :posts, source: :taggings
has_many :taggings_2, through: :posts, source: :tagging
has_many :tags, through: :posts
has_many :ordered_tags, through: :posts
has_many :post_categories, through: :posts, source: :categories
has_many :tagging_tags, through: :taggings, source: :tag
has_many :similar_posts, -> { distinct }, through: :tags, source: :tagged_posts
has_many :ordered_posts, -> { distinct }, through: :ordered_tags, source: :tagged_posts
has_many :distinct_tags, -> { select("DISTINCT tags.*").order("tags.name") }, through: :posts, source: :tags
has_many :tags_with_primary_key, through: :posts
has_many :books
has_many :published_books, class_name: "PublishedBook"
has_many :unpublished_books, -> { where(status: [:proposed, :written]) }, class_name: "Book"
has_many :subscriptions, through: :books
has_many :subscribers, -> { order("subscribers.nick") }, through: :subscriptions
has_many :distinct_subscribers, -> { select("DISTINCT subscribers.*").order("subscribers.nick") }, through: :subscriptions, source: :subscriber
has_one :essay, primary_key: :name, as: :writer
has_one :essay_category, through: :essay, source: :category
has_one :essay_owner, through: :essay, source: :owner
has_one :essay_2, primary_key: :name, class_name: "Essay", foreign_key: :author_id
has_one :essay_category_2, through: :essay_2, source: :category
has_many :essays, primary_key: :name, as: :writer
has_many :essay_categories, through: :essays, source: :category
has_many :essay_owners, through: :essays, source: :owner
has_many :essays_2, primary_key: :name, class_name: "Essay", foreign_key: :author_id
has_many :essay_categories_2, through: :essays_2, source: :category
belongs_to :owned_essay, primary_key: :name, class_name: "Essay"
has_one :owned_essay_category, through: :owned_essay, source: :category
belongs_to :author_address, dependent: :destroy
belongs_to :author_address_extra, dependent: :delete, class_name: "AuthorAddress"
has_many :category_post_comments, through: :categories, source: :post_comments
has_many :misc_posts, -> { where(posts: { title: ["misc post by bob", "misc post by mary"] }) }, class_name: "Post"
has_many :misc_post_first_blue_tags, through: :misc_posts, source: :first_blue_tags
has_many :misc_post_first_blue_tags_2, -> { where(posts: { title: ["misc post by bob", "misc post by mary"] }) },
through: :posts, source: :first_blue_tags_2
has_many :posts_with_default_include, class_name: "PostWithDefaultInclude"
has_many :comments_on_posts_with_default_include, through: :posts_with_default_include, source: :comments
has_many :posts_with_signature, ->(record) { where("posts.title LIKE ?", "%by #{record.name.downcase}%") }, class_name: "Post"
has_many :posts_mentioning_author, ->(record = nil) { where("posts.body LIKE ?", "%#{record&.name&.downcase}%") }, class_name: "Post"
has_one :recent_post, -> { order(id: :desc) }, class_name: "Post"
has_one :recent_response, through: :recent_post, source: :comments
has_many :posts_with_extension, -> { order(:title) }, class_name: "Post" do
def extension_method; end
end
has_many :posts_with_extension_and_instance, ->(record) { order(:title) }, class_name: "Post" do
def extension_method; end
end
has_many :top_posts, -> { order(id: :asc) }, class_name: "Post"
has_many :other_top_posts, -> { order(id: :asc) }, class_name: "Post"
has_many :topics, primary_key: "name", foreign_key: "author_name"
has_many :topics_without_type, -> { select(:id, :title, :author_name) },
class_name: "Topic", primary_key: "name", foreign_key: "author_name"
has_many :lazy_readers_skimmers_or_not, through: :posts
has_many :lazy_readers_skimmers_or_not_2, through: :posts_with_no_comments, source: :lazy_readers_skimmers_or_not
has_many :lazy_readers_skimmers_or_not_3, through: :posts_with_no_comments_2, source: :lazy_readers_skimmers_or_not
attr_accessor :post_log
after_initialize :set_post_log
def set_post_log
@post_log = []
end
def label
"#{id}-#{name}"
end
def social
%w(twitter github)
end
validates_presence_of :name
private
def throw_abort(_)
throw(:abort)
end
def ensure_not_called(_)
raise
end
def log_before_adding(object)
@post_log << "before_adding#{object.id || '<new>'}"
end
def log_after_adding(object)
@post_log << "after_adding#{object.id}"
end
def log_before_removing(object)
@post_log << "before_removing#{object.id}"
end
def log_after_removing(object)
@post_log << "after_removing#{object.id}"
end
def raise_exception(object)
raise Exception.new("You can't add a post")
end
end
class AuthorAddress < ActiveRecord::Base
has_one :author
def self.destroyed_author_address_ids
@destroyed_author_address_ids ||= []
end
before_destroy do |author_address|
AuthorAddress.destroyed_author_address_ids << author_address.id
end
end
class AuthorFavorite < ActiveRecord::Base
belongs_to :author
belongs_to :favorite_author, class_name: "Author"
end
class AuthorFavoriteWithScope < ActiveRecord::Base
self.table_name = "author_favorites"
default_scope { order(id: :asc) }
belongs_to :author
belongs_to :favorite_author, class_name: "Author"
end