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Diffstat (limited to 'app/models/concerns/subquery.rb')
| -rw-r--r-- | app/models/concerns/subquery.rb | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/app/models/concerns/subquery.rb b/app/models/concerns/subquery.rb new file mode 100644 index 00000000000..ae92d2137c1 --- /dev/null +++ b/app/models/concerns/subquery.rb @@ -0,0 +1,24 @@ +# frozen_string_literal: true + +# Distinguish between a top level query and a subselect. +# +# Retrieve column values when the relation has already been loaded, otherwise reselect the relation. +# Useful for preload query patterns where the typical Rails #preload does not fit. Such as: +# +# projects = Project.where(...) +# projects.load +# ... +# options[members] = ProjectMember.where(...).where(source_id: projects.select(:id)) +module Subquery + extend ActiveSupport::Concern + + class_methods do + def subquery(*column_names, max_limit: 5_000) + if current_scope.loaded? && current_scope.size <= max_limit + current_scope.pluck(*column_names) + else + current_scope.reselect(*column_names) + end + end + end +end |