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# frozen-string-literal: true
module Sequel
class Database
# ---------------------
# :section: 5 - Methods that set defaults for created datasets
# This methods change the default behavior of this database's datasets.
# ---------------------
# The class to use for creating datasets. Should respond to
# new with the Database argument as the first argument, and
# an optional options hash.
attr_reader :dataset_class
# If the database has any dataset modules associated with it,
# use a subclass of the given class that includes the modules
# as the dataset class.
def dataset_class=(c)
unless @dataset_modules.empty?
c = Class.new(c)
@dataset_modules.each{|m| c.send(:include, m)}
end
@dataset_class = c
reset_default_dataset
end
# Equivalent to extending all datasets produced by the database with a
# module. What it actually does is use a subclass of the current dataset_class
# as the new dataset_class, and include the module in the subclass.
# Instead of a module, you can provide a block that is used to create an
# anonymous module.
#
# This allows you to override any of the dataset methods even if they are
# defined directly on the dataset class that this Database object uses.
#
# If a block is given, a Dataset::DatasetModule instance is created, allowing
# for the easy creation of named dataset methods that will do caching.
#
# Examples:
#
# # Introspect columns for all of DB's datasets
# DB.extend_datasets(Sequel::ColumnsIntrospection)
#
# # Trace all SELECT queries by printing the SQL and the full backtrace
# DB.extend_datasets do
# def fetch_rows(sql)
# puts sql
# puts caller
# super
# end
# end
#
# # Add some named dataset methods
# DB.extend_datasets do
# order :by_id, :id
# select :with_id_and_name, :id, :name
# where :active, :active
# end
#
# DB[:table].active.with_id_and_name.by_id
# # SELECT id, name FROM table WHERE active ORDER BY id
def extend_datasets(mod=nil, &block)
raise(Error, "must provide either mod or block, not both") if mod && block
mod = Dataset::DatasetModule.new(&block) if block
if @dataset_modules.empty?
@dataset_modules = [mod]
@dataset_class = Class.new(@dataset_class)
else
@dataset_modules << mod
end
@dataset_class.send(:include, mod)
reset_default_dataset
end
private
# The default dataset class to use for the database
def dataset_class_default
Sequel::Dataset
end
# Reset the default dataset used by most Database methods that create datasets.
def reset_default_dataset
Sequel.synchronize{@symbol_literal_cache.clear}
@default_dataset = dataset
end
# Whether to quote identifiers by default for this database, true by default.
def quote_identifiers_default
true
end
end
end
|
