def merge(r)
return self unless r
return to_a & r if r.is_a?(Array)
merged_relation = clone
r = r.with_default_scope if r.default_scoped? && r.klass != klass
Relation::ASSOCIATION_METHODS.each do |method|
value = r.send("#{method}_values""#{method}_values")
unless value.empty?
if method == :includes
merged_relation = merged_relation.includes(value)
else
merged_relation.send("#{method}_values=""#{method}_values=", value)
end
end
end
(Relation::MULTI_VALUE_METHODS - [:joins, :where, :order]).each do |method|
value = r.send("#{method}_values""#{method}_values")
merged_relation.send("#{method}_values=""#{method}_values=", merged_relation.send("#{method}_values""#{method}_values") + value) if value.present?
end
merged_relation.joins_values += r.joins_values
merged_wheres = @where_values + r.where_values
unless @where_values.empty?
seen = Hash.new { |h,table| h[table] = {} }
merged_wheres = merged_wheres.reverse.reject { |w|
nuke = false
if w.respond_to?(:operator) && w.operator == :==
name = w.left.name
table = w.left.relation.name
nuke = seen[table][name]
seen[table][name] = true
end
nuke
}.reverse
end
merged_relation.where_values = merged_wheres
(Relation::SINGLE_VALUE_METHODS - [:lock, :create_with, :reordering]).each do |method|
value = r.send("#{method}_value""#{method}_value")
merged_relation.send("#{method}_value=""#{method}_value=", value) unless value.nil?
end
merged_relation.lock_value = r.lock_value unless merged_relation.lock_value
merged_relation = merged_relation.create_with(r.create_with_value) unless r.create_with_value.empty?
if (r.reordering_value)
merged_relation.reordering_value = true
merged_relation.order_values = r.order_values
else
merged_relation.order_values += r.order_values
end
merged_relation.send :apply_modules, r.extensions
merged_relation
end