8a72f5c427
This commit adds the module `FromUnion`, which provides the class method
`from_union`. This simplifies the process of selecting data from the
result of a UNION, and reduces the likelihood of making mistakes. As a
result, instead of this:
union = Gitlab::SQL::Union.new([foo, bar])
Foo.from("(#{union.to_sql}) #{Foo.table_name}")
We can now write this instead:
Foo.from_union([foo, bar])
This commit also includes some changes to make this new setup work
properly. For example, a bug in Rails 4
(https://github.com/rails/rails/issues/24193) would break the use of
`from("sub-query-here").includes(:relation)` in certain cases. There was
also a CI query which appeared to repeat a lot of conditions from an
outer query on an inner query, which isn't necessary.
Finally, we include a RuboCop cop to ensure developers use this new
module, instead of using Gitlab::SQL::Union directly.
Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/51307
40 lines
1,006 B
Ruby
40 lines
1,006 B
Ruby
# frozen_string_literal: true
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require 'spec_helper'
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describe FromUnion do
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describe '.from_union' do
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let(:model) do
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Class.new(ActiveRecord::Base) do
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self.table_name = 'users'
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include FromUnion
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end
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end
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it 'selects from the results of the UNION' do
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query = model.from_union([model.where(id: 1), model.where(id: 2)])
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expect(query.to_sql).to match(/FROM \(SELECT.+UNION.+SELECT.+\) users/m)
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end
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it 'supports the use of a custom alias for the sub query' do
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query = model.from_union(
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[model.where(id: 1), model.where(id: 2)],
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alias_as: 'kittens'
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)
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expect(query.to_sql).to match(/FROM \(SELECT.+UNION.+SELECT.+\) kittens/m)
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end
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it 'supports keeping duplicate rows' do
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query = model.from_union(
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[model.where(id: 1), model.where(id: 2)],
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remove_duplicates: false
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)
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expect(query.to_sql)
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.to match(/FROM \(SELECT.+UNION ALL.+SELECT.+\) users/m)
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end
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end
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end
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