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# frozen-string-literal: true
#
# The constant_sql_override extension allows you to change the SQL
# generated for Sequel constants.
#
# One possible use-case for this is to have Sequel::CURRENT_TIMESTAMP use UTC time when
# you have Sequel.database_timezone = :utc, but the database uses localtime when
# generating CURRENT_TIMESTAMP.
#
# You can set SQL overrides with Database#set_constant_sql:
#
# DB.set_constant_sql(Sequel::CURRENT_TIMESTAMP, "CURRENT_TIMESTAMP AT TIME ZONE 'UTC'")
#
# Now, using Sequel::CURRENT_TIMESTAMP will use your override instead:
#
# Album.where(released_at: Sequel::CURRENT_TIMESTAMP).sql
# # => SELECT "albums.*" FROM "albums" WHERE ("released_at" = CURRENT_TIMESTAMP AT TIME ZONE 'UTC')
#
# To use this extension, first load it into your Sequel::Database instance:
#
# DB.extension :constant_sql_override
#
# Related module: Sequel::ConstantSqlOverride
#
module Sequel
module ConstantSqlOverride
module DatabaseMethods
# Create the initial empty hash of constant sql overrides.
def self.extended(db)
db.instance_exec do
@constant_sqls ||= {}
extend_datasets(DatasetMethods)
end
end
# Hash mapping constant symbols to SQL. For internal use only.
attr_reader :constant_sqls # :nodoc:
# Set the SQL to use for the given Sequel::SQL::Constant
def set_constant_sql(constant, override)
@constant_sqls[constant.constant] = override
end
# Freeze the constant_sqls hash to prevent adding new overrides.
def freeze
@constant_sqls.freeze
super
end
end
module DatasetMethods
# Use overridden constant SQL
def constant_sql_append(sql, constant)
if constant_sql = db.constant_sqls[constant]
sql << constant_sql
else
super
end
end
end
end
Database.register_extension(:constant_sql_override, ConstantSqlOverride::DatabaseMethods)
end
|
