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# frozen-string-literal: true
#
# The implicit_subquery extension changes most dataset methods that
# return modified datasets to implicitly call from_self if the database
# currently uses raw SQL. Sequel's by default does not do this:
#
# DB["SELECT * FROM table"].select(:column).sql
# # => "SELECT * FROM table"
#
# With this extension, datasets that use raw SQL are implicitly wrapped
# in a subquery:
#
# DB["SELECT * FROM table"].select(:column).sql
# # => "SELECT column FROM (SELECT * FROM table) AS t1"
#
# To add this extension to an existing dataset:
#
# ds = ds.extension(:implicit_subquery)
#
# To set this as the default behavior for all datasets on a single database:
#
# DB.extension(:implicit_subquery)
#
# Related module: Sequel::Dataset::ImplicitSubquery
#
module Sequel
class Dataset
module ImplicitSubquery
exceptions = [:add_graph_aliases, :filter, :from, :from_self, :naked, :or, :order_more,
:qualify, :reverse, :reverse_order, :select_all, :select_more, :server,
:set_graph_aliases, :unfiltered, :ungraphed, :ungrouped, :unlimited, :unordered,
:with_sql]
additions = [:join_table]
(Dataset::QUERY_METHODS - Dataset::JOIN_METHODS - exceptions + additions).each do |meth|
define_method(meth) do |*a, &b|
if opts[:sql]
from_self.public_send(meth, *a, &b)
else
super(*a, &b)
end
end
end
end
register_extension(:implicit_subquery, ImplicitSubquery)
end
end
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