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# frozen-string-literal: true
require 'delegate'
module Sequel
module Plugins
# The defaults_setter plugin makes the column getter methods return the default
# values for new objects, if the values have not already been set. Example:
#
# # column a default NULL
# # column b default 2
# album = Album.new
# album.a # => nil
# album.b # => 2
# album = Album.new(a: 1, b: 3)
# album.a # => 1
# album.b # => 3
#
# You can manually set default values as well:
#
# Album.default_values[:a] = 4
# Album.new.a # => 4
#
# You can also provide procs to set default values:
#
# Album.default_values[:a] = lambda{Date.today}
# Album.new.a # => Date.today
#
# If the proc accepts a single argument, it is passed the instance, allowing
# default values to depend on instance-specific state:
#
# Album.default_values[:a] = lambda{|album| album.b + 1}
# Album.new(b: 10).a # => 11
#
# By default, default values returned are not cached:
#
# Album.new.a.equal?(Album.new.a) # => false
#
# However, you can turn on caching of default values:
#
# Album.plugin :defaults_setter, cache: true
# Album.new.a.equal?(Album.new.a) # => false
#
# Note that if the cache is turned on, the cached values are stored in
# the values hash:
#
# Album.plugin :defaults_setter, cache: true
# album = Album.new
# album.values # => {}
# album.a
# album.values # => {:a => Date.today}
#
# Usage:
#
# # Make all model subclass instances set defaults (called before loading subclasses)
# Sequel::Model.plugin :defaults_setter
#
# # Make the Album class set defaults
# Album.plugin :defaults_setter
module DefaultsSetter
# Set the default values based on the model schema. Options:
# :cache :: Cache default values returned in the model's values hash.
def self.configure(model, opts=OPTS)
model.instance_exec do
set_default_values
@cache_default_values = opts[:cache] if opts.has_key?(:cache)
end
end
module ClassMethods
# The default values to use for this model. A hash with column symbol
# keys and default values. If the default values respond to +call+, it will be called
# to get the value, otherwise the value will be used directly. You can manually modify
# this hash to set specific default values, by default the ones will be parsed from the database.
attr_reader :default_values
Plugins.after_set_dataset(self, :set_default_values)
Plugins.inherited_instance_variables(self, :@default_values=>:dup, :@cache_default_values=>nil)
# Whether default values should be cached in the values hash after being retrieved.
def cache_default_values?
@cache_default_values
end
# Freeze default values when freezing model class
def freeze
@default_values.freeze
super
end
private
# Parse the cached database schema for this model and set the default values appropriately.
def set_default_values
h = {}
if @db_schema
@db_schema.each do |k, v|
if v[:callable_default]
h[k] = v[:callable_default]
elsif !v[:ruby_default].nil?
h[k] = convert_default_value(v[:ruby_default])
end
end
end
@default_values = h.merge!(@default_values || OPTS)
end
# Handle the CURRENT_DATE and CURRENT_TIMESTAMP values specially by returning an appropriate Date or
# Time/DateTime value.
def convert_default_value(v)
case v
when Sequel::CURRENT_DATE
lambda{Date.today}
when Sequel::CURRENT_TIMESTAMP
lambda{dataset.current_datetime}
when Hash, Array
v = Marshal.dump(v).freeze
lambda{Marshal.load(v)}
when Delegator
# DelegateClass returns an anonymous case, which cannot be marshalled, so marshal the
# underlying object and create a new instance of the class with the unmarshalled object.
klass = v.class
case o = v.__getobj__
when Hash, Array
v = Marshal.dump(o).freeze
lambda{klass.new(Marshal.load(v))}
else
v
end
else
v
end
end
end
module InstanceMethods
# Use default value for a new record if values doesn't already contain an entry for it.
def [](k)
if new? && !values.has_key?(k)
v = model.default_values.fetch(k){return}
if v.respond_to?(:call)
v = if v.respond_to?(:arity) && v.arity == 1
v.call(self)
else
v.call
end
end
values[k] = v if model.cache_default_values?
v
else
super
end
end
end
end
end
end
|
