open_struct_values.rb

module Sequel
  module OpenStructValues
    # Set overrides/defaults for inserting Openstruct
    def insert_sql(*values)
      p "Should get called"
    end
  end

  Dataset.register_extension(:open_struct_values, OpenStructValues)
end

# ...

dataset = @db[:posts]
dataset.extension(:open_struct_values)

dataset.insert(foo: 'bar') # => Nothing gets printed.