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# frozen-string-literal: true
#
# The identifier_mangling extension adds support for to change
# the default identifier mangling for datasets, as well as all
# datasets for a given database.
#
# # Use uppercase identifiers in database, and lowercase in ruby.
# # Default behavior of Sequel, as the SQL standard behavior
# # folds unquoted identifiers to uppercase.
# DB.identifier_input_method = :upcase
# DB.identifier_output_method = :downcase
#
# # Don't modify identifiers.
# # Default behavior of Sequel on PostgreSQL, MySQL, SQLite,
# # as they fold unquoted identifiers to lowercase.
# DB.identifier_input_method = nil
# DB.identifier_output_method = nil
#
# You can also choose to turn on or off identifier quoting:
#
# # Quote identifiers. Sequel's default behavior.
# DB.quote_identifiers = true
#
# # Don't quote identifiers. Sequel's default behavior on DB2.
# DB.quote_identifiers = false
#
# To modify the identifiers on a per-dataset basis:
#
# ds = DB[:a].with_input_indentifier(:upcase).
# with_output_identifier(:downcase).
# with_quote_identifiers(true)
#
# To load the extension into the database:
#
# DB.extension :identifier_mangling
#
# Related modules: Sequel::IdentifierMangling::DatabaseMethods,
# Sequel::IdentifierMangling::DatasetMethods
#
module Sequel
module IdentifierMangling
module DatabaseMethods
def self.extended(db)
db.instance_exec do
@identifier_input_method = nil
@identifier_output_method = nil
@quote_identifiers = nil
reset_identifier_mangling
extend_datasets(DatasetMethods)
end
end
# The identifier input method to use by default for this database (default: adapter default)
attr_reader :identifier_input_method
# The identifier output method to use by default for this database (default: adapter default)
attr_reader :identifier_output_method
# Set the method to call on identifiers going into the database:
#
# DB[:items] # SELECT * FROM items
# DB.identifier_input_method = :upcase
# DB[:items] # SELECT * FROM ITEMS
def identifier_input_method=(v)
reset_default_dataset
@identifier_input_method = v
end
# Set the method to call on identifiers coming from the database:
#
# DB[:items].first # {:id=>1, :name=>'foo'}
# DB.identifier_output_method = :upcase
# DB[:items].first # {:ID=>1, :NAME=>'foo'}
def identifier_output_method=(v)
reset_default_dataset
@identifier_output_method = v
end
# Set whether to quote identifiers (columns and tables) for this database:
#
# DB[:items] # SELECT * FROM items
# DB.quote_identifiers = true
# DB[:items] # SELECT * FROM "items"
def quote_identifiers=(v)
reset_default_dataset
@quote_identifiers = v
end
# Returns true if the database quotes identifiers.
def quote_identifiers?
@quote_identifiers
end
private
# Return a dataset that uses the default identifier input and output methods
# for this database. Used when parsing metadata so that column symbols are
# returned as expected.
def _metadata_dataset
super.
with_identifier_input_method(identifier_input_method_default).
with_identifier_output_method(identifier_output_method_default)
end
# Upcase identifiers on input if database folds unquoted identifiers to
# uppercase.
def identifier_input_method_default
return super if defined?(super)
:upcase if folds_unquoted_identifiers_to_uppercase?
end
# Downcase identifiers on output if database folds unquoted identifiers to
# uppercase.
def identifier_output_method_default
return super if defined?(super)
:downcase if folds_unquoted_identifiers_to_uppercase?
end
# Reset the identifier mangling options. Overrides any already set on
# the instance. Only for internal use by shared adapters.
def reset_identifier_mangling
@quote_identifiers = @opts.fetch(:quote_identifiers, quote_identifiers_default)
@identifier_input_method = @opts.fetch(:identifier_input_method, identifier_input_method_default)
@identifier_output_method = @opts.fetch(:identifier_output_method, identifier_output_method_default)
reset_default_dataset
end
end
module DatasetMethods
# The String instance method to call on identifiers before sending them to
# the database.
def identifier_input_method
@opts.fetch(:identifier_input_method, db.identifier_input_method)
end
# The String instance method to call on identifiers before sending them to
# the database.
def identifier_output_method
@opts.fetch(:identifier_output_method, db.identifier_output_method)
end
# Check with the database to see if identifier quoting is enabled
def quote_identifiers?
@opts.fetch(:quote_identifiers, db.quote_identifiers?)
end
# Return a modified dataset with identifier_input_method set.
def with_identifier_input_method(meth)
clone(:identifier_input_method=>meth, :skip_symbol_cache=>true)
end
# Return a modified dataset with identifier_output_method set.
def with_identifier_output_method(meth)
clone(:identifier_output_method=>meth)
end
private
# Convert the identifier to the version used in the database via
# identifier_input_method.
def input_identifier(v)
(i = identifier_input_method) ? v.to_s.public_send(i) : v.to_s
end
# Modify the identifier returned from the database based on the
# identifier_output_method.
def output_identifier(v)
v = 'untitled' if v == ''
(i = identifier_output_method) ? v.to_s.public_send(i).to_sym : v.to_sym
end
def non_sql_option?(key)
super || key == :identifier_input_method || key == :identifier_output_method
end
end
end
Database.register_extension(:identifier_mangling, IdentifierMangling::DatabaseMethods)
end
|
