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count_sql_for
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| module AssociationCounter | |
| def count_sql_for(association_sym) | |
| association_table_name = reflect_on_association(association_sym).klass.table_name | |
| select("count(#{association_table_name}.id) as #{association_sym}_count").joins(association_sym).to_sql | |
| end | |
| end | |
| ActiveRecord::Base.send(:extend, AssociationCounter) |
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| clas Bar < ActiveRecord::Base | |
| scope :no_foos, lambda{ joins(:foos).where("(#{count_sql_for(:foos)}) = 0") } | |
| end |
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you don't need to call #to_s inside the string interpolation. It will call it implicitly on a symbol.