Created
March 10, 2016 17:41
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Extends the functionality set forth in union_scope.rb, to include EXCEPT and INTERSECT operations
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module ActiveRecord | |
module Scopes | |
module SetOperations | |
extend ActiveSupport::Concern | |
class_methods do | |
def union_scope(*scopes) | |
apply_operation 'UNION', scopes | |
end | |
def intersect_scope(*scopes) | |
apply_operation 'INTERSECT', scopes | |
end | |
def except_scope(*scopes) | |
apply_operation 'EXCEPT', scopes | |
end | |
private | |
def apply_operation(operation, scopes) | |
id_column = "#{table_name}.#{primary_key}" | |
sub_query = scopes | |
.map { |s| s.select(id_column).to_sql } | |
.join(" #{operation} ") | |
where "#{id_column} IN (#{sub_query})" | |
end | |
end | |
end | |
end | |
end |
Less problems and easier to follow:
def union_scope(*scopes)
scopes.inject(self) { |all, scope| all.or(where(id: scope)) }
end
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For how to use it, please refer: https://stackoverflow.com/questions/6686920/activerecord-query-union
And you may need to change
def union_scope(*scopes)
todef union_scope(scopes)
to run it successfully.