105 lines
2.8 KiB
Ruby
105 lines
2.8 KiB
Ruby
module Gitlab
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# Retrieving of parent or child groups based on a base ActiveRecord relation.
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#
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# This class uses recursive CTEs and as a result will only work on PostgreSQL.
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class GroupHierarchy
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attr_reader :base, :model
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# base - An instance of ActiveRecord::Relation for which to get parent or
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# child groups.
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def initialize(base)
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@base = base
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@model = base.model
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end
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# Returns a relation that includes the base set of groups and all their
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# ancestors (recursively).
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def base_and_ancestors
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return model.none unless Group.supports_nested_groups?
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base_and_ancestors_cte.apply_to(model.all)
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end
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# Returns a relation that includes the base set of groups and all their
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# descendants (recursively).
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def base_and_descendants
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return model.none unless Group.supports_nested_groups?
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base_and_descendants_cte.apply_to(model.all)
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end
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# Returns a relation that includes the base groups, their ancestors, and the
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# descendants of the base groups.
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#
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# The resulting query will roughly look like the following:
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#
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# WITH RECURSIVE ancestors AS ( ... ),
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# descendants AS ( ... )
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# SELECT *
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# FROM (
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# SELECT *
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# FROM ancestors namespaces
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#
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# UNION
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#
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# SELECT *
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# FROM descendants namespaces
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# ) groups;
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#
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# Using this approach allows us to further add criteria to the relation with
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# Rails thinking it's selecting data the usual way.
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def all_groups
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return base unless Group.supports_nested_groups?
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ancestors = base_and_ancestors_cte
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descendants = base_and_descendants_cte
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ancestors_table = ancestors.alias_to(groups_table)
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descendants_table = descendants.alias_to(groups_table)
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union = SQL::Union.new([model.unscoped.from(ancestors_table),
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model.unscoped.from(descendants_table)])
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model.
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unscoped.
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with.
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recursive(ancestors.to_arel, descendants.to_arel).
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from("(#{union.to_sql}) #{model.table_name}")
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end
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private
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def base_and_ancestors_cte
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cte = SQL::RecursiveCTE.new(:base_and_ancestors)
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cte << base.except(:order)
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# Recursively get all the ancestors of the base set.
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cte << model.
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from([groups_table, cte.table]).
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where(groups_table[:id].eq(cte.table[:parent_id])).
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except(:order)
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cte
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end
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def base_and_descendants_cte
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cte = SQL::RecursiveCTE.new(:base_and_descendants)
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cte << base.except(:order)
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# Recursively get all the descendants of the base set.
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cte << model.
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from([groups_table, cte.table]).
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where(groups_table[:parent_id].eq(cte.table[:id])).
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except(:order)
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cte
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end
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def groups_table
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model.arel_table
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end
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end
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end
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