119 lines
4.1 KiB
Ruby
119 lines
4.1 KiB
Ruby
require 'minitest/autorun'
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require 'prism'
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require 'tmpdir'
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# Covers has_many :through where the through step is a belongs_to (the
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# owner holds the foreign key, so many owners can share one through
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# record) rather than a has_many/has_one (owner.id looked up by foreign
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# key on the through table). Both the lazy reader and the includes()
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# eager-load path need to handle this shape.
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class OrmHasManyThroughBelongsToTest < Minitest::Test
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def setup
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@dir = Dir.mktmpdir('prism-through-belongs-to-store')
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@store = CountingBelongsToThroughStore.new(File.join(@dir, 'test.pstore'))
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@store.create_table(:posts, %w[id title])
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@store.create_table(:comments, %w[id post_id body])
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post_class = Class.new(Prism::Orm::Model) do
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table_name :posts
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has_many :comments, class_name: 'Comment', foreign_key: 'post_id', dependent: :destroy
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end
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comment_class = Class.new(Prism::Orm::Model) do
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table_name :comments
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belongs_to :post, class_name: 'Post', foreign_key: 'post_id'
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has_many :co_comments, through: :post, source: :comments
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end
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[post_class, comment_class].each { |klass| klass.store = @store }
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Object.const_set(:Post, post_class)
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Object.const_set(:Comment, comment_class)
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end
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def teardown
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FileUtils.remove_entry(@dir)
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%i[Post Comment].each { |name| Object.send(:remove_const, name) if Object.const_defined?(name) }
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end
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def test_has_many_through_belongs_to_collects_source_records
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post = Post.create!(title: 'hello world')
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first = Comment.create!(post_id: post.id, body: 'first')
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second = Comment.create!(post_id: post.id, body: 'second')
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ids = first.co_comments.map(&:id).sort
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assert_equal [first.id, second.id].sort, ids
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end
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def test_has_many_through_belongs_to_scopes_to_own_post
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post_a = Post.create!(title: 'a')
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post_b = Post.create!(title: 'b')
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comment_a = Comment.create!(post_id: post_a.id, body: 'on a')
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Comment.create!(post_id: post_b.id, body: 'on b')
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assert_equal [comment_a.id], comment_a.co_comments.map(&:id)
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end
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def test_has_many_through_belongs_to_returns_empty_without_owner
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orphan = Comment.new(post_id: nil, body: 'no post')
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assert_equal [], orphan.co_comments
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end
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def test_includes_has_many_through_belongs_to_avoids_n_plus_one_queries
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3.times do |i|
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post = Post.create!(title: "post#{i}")
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2.times { |j| Comment.create!(post_id: post.id, body: "c#{i}-#{j}") }
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end
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@store.reset_query_count!
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comments = Comment.all.includes(:co_comments).to_a
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baseline = @store.query_count
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total = comments.sum { |comment| comment.co_comments.size }
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assert_equal baseline, @store.query_count,
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"expected preloaded #co_comments to be free, but it issued #{@store.query_count - baseline} more queries"
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assert_equal 12, total
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end
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def test_includes_has_many_through_belongs_to_shares_one_through_record
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post = Post.create!(title: 'shared')
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Comment.create!(post_id: post.id, body: 'x')
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Comment.create!(post_id: post.id, body: 'y')
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@store.reset_query_count!
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comments = Comment.all.includes(:co_comments).to_a
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# one query to load comments, one to batch-load its source comments by
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# post_id (no index on that column here, so still a real #all scan).
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# Batch-loading the (single, shared) through post by id is NOT a third
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# counted query: Store#lookup_by_index_in treats the primary key as
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# always indexed (#rows is already a Hash keyed by id) and this
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# counting store only wraps #all/#find, not the index lookup methods -
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# see Store#lookup_by_index_in.
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assert_equal 2, @store.query_count
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assert_equal [2, 2], comments.map { |comment| comment.co_comments.size }
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end
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end
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# Wraps Store#all/#find to count reads, mirroring
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# test_orm_has_many_through.rb's CountingThroughStore so this file has no
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# load-order dependency on it.
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class CountingBelongsToThroughStore < Prism::Orm::Store
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def initialize(*)
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super
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@query_count = 0
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end
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attr_reader :query_count
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def reset_query_count!
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@query_count = 0
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end
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def all(table)
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@query_count += 1
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super
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end
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def find(table, id)
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@query_count += 1
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super
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end
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end
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