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Fix "last equality wins" logic in relation merge

This is a real fix (as compared to the band-aid in b127d86), which uses
the recently-added equality methods for ARel nodes. It has the side
benefit of simplifying the merge code a bit.
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commit bf80522be4d7ac521fa3c30d889afa68450a0bc2 1 parent f9fc26e
@ernie ernie authored
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15 activerecord/lib/active_record/relation/merger.rb
@@ -97,18 +97,13 @@ def merged_wheres
merged_wheres = relation.where_values + values[:where]
unless relation.where_values.empty?
- # Remove duplicate ARel attributes. Last one wins.
- seen = Hash.new { |h,table| h[table] = {} }
+ # Remove equalities with duplicated left-hand. Last one wins.
+ seen = {}
merged_wheres = merged_wheres.reverse.reject { |w|
nuke = false
- # We might have non-attributes on the left side of equality nodes,
- # so we need to make sure they quack like an attribute.
- if w.respond_to?(:operator) && w.operator == :== &&
- w.left.respond_to?(:relation)
- name = w.left.name
- table = w.left.relation.name
- nuke = seen[table][name]
- seen[table][name] = true
+ if w.respond_to?(:operator) && w.operator == :==
+ nuke = seen[w.left]
+ seen[w.left] = true
end
nuke
}.reverse
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11 activerecord/test/cases/relations_test.rb
@@ -675,11 +675,14 @@ def test_relation_merging_with_arel_equalities_keeps_last_equality
assert_equal [developers(:poor_jamis)], devs.to_a
end
- def test_relation_merging_with_arel_equalities_with_a_non_attribute_left_hand_ignores_non_attributes_when_discarding_equalities
+ def test_relation_merging_with_arel_equalities_keeps_last_equality_with_non_attribute_left_hand
salary_attr = Developer.arel_table[:salary]
- devs = Developer.where(salary_attr.eq(80000)).merge(
- Developer.where(salary_attr.eq(9000)).
- where(Arel::Nodes::NamedFunction.new('abs', [salary_attr]).eq(9000))
+ devs = Developer.where(
+ Arel::Nodes::NamedFunction.new('abs', [salary_attr]).eq(80000)
+ ).merge(
+ Developer.where(
+ Arel::Nodes::NamedFunction.new('abs', [salary_attr]).eq(9000)
+ )
)
assert_equal [developers(:poor_jamis)], devs.to_a
end

2 comments on commit bf80522

@tjwallace

@ernie why is there "last equality wins" logic anyways? If a users generates a query with WHERE column = 1 AND column = 2, why not let it return no records? This is related to my question/bug #6596.

@ernie
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