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@lsiden
Last active February 7, 2018 17:53
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module ActiveRecord::UnionScope
#https://gist.github.com/tlowrimore/5162327
#http://stackoverflow.com/a/15413611/270511
module ActiveRecord::UnionScope
def self.included(base)
base.send :extend, ClassMethods
end
module ClassMethods
def union_scope(*scopes)
id_column = "#{table_name}.id"
if (sub_query = scopes.reject { |sc| sc.count == 0 }.map { |s| s.select(id_column).to_sql }.join(" UNION ")).present?
where "#{id_column} IN (#{sub_query})"
else
none
end
end
end
end
@lsiden
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lsiden commented Jul 24, 2014

Just fixed this by counting the scopes that actually return something. The previous way failed sometimes.

@lsiden
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lsiden commented Jul 25, 2014

Even better!

@abdul-shajin
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If my scopes accept arguments, will it work ??

@bogdanRada
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this is correct but needs just small change:

This code:

 map { |s| s.select(id_column).to_sql }

should be replaced with this:

.map { |s|   "(#{s.select(id_column).to_sql})" }

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