95 lines
2.8 KiB
Ruby
95 lines
2.8 KiB
Ruby
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# == Default Values
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#
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# Allows default attributes values to be declared. The callback used to set the values can be controlled via options.
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#
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# The following option keys are allowed:
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# `:on`. If omitted, it defaults to :initialize.
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# :on may be one of the following: :initialize, :create, :update, :save
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#
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# `:empty`. If omitted, it defaults to only updating `nil` values
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# :empty should be a lambda (or proc) that accepts the current value of the attribute and returns true if the value
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# should be replaced by the default
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#
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# Examples:
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# Sets `attr` to 'default' and `attr2` to 'default' any time the class is instantiated
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# default_values {
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# attr: 'default',
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# attr2: 'default'
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# }
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#
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# Sets `roles` to [:super_admin] only when saving a new object and only if roles is an empty array (it will not update a nil value)
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# default_values({roles: [:super_admin]}, {on: :create, empty: ->(v) { v == [] }})
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#
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module DefaultValues
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extend ActiveSupport::Concern
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DEFAULT_OPTIONS = { on: :initialize }
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DefaultValue = Struct.new(:value, :options)
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included do
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class_attribute :_default_values
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self._default_values = {}
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after_initialize :set_default_values_initialize
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before_create :set_default_values_create
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before_update :set_default_values_update
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before_save :set_default_values_save
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end
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def set_default_values_initialize
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set_default_values(:initialize)
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end
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def set_default_values_create
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set_default_values(:create)
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end
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def set_default_values_update
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set_default_values(:update)
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end
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def set_default_values_save
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set_default_values(:save)
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end
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def set_default_values(on)
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_default_values.each do |k, dv|
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if dv.options[:on].to_sym == on
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v = dv.value
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v_lambda = Proc === v ? v : -> { v }
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tester = dv.options[:empty] || ->(x) { x.nil? }
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self.send("#{k}=", self.instance_exec(&v_lambda)) if self.respond_to?(k) && tester.call(self.send(k))
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end
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end
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end
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module ClassMethods
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# Copy defaults on inheritance.
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def inherited(base)
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base._default_values = _default_values.dup
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super
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end
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def default_values(defaults_hash, options = {})
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options = DEFAULT_OPTIONS.merge(options.symbolize_keys)
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valid_ons = [:initialize, :create, :update, :save]
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unless valid_ons.include? options[:on]
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raise "Invalid options[:on] value: [#{options[:on]}]. Must be one of these symbols: #{valid_ons.join(', ')}"
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end
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if options[:empty].present?
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proc = options[:empty]
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raise "Invalid options[:empty]. Must be a Proc or Lambda with an arity of 1" unless (proc.is_a?(Proc) && proc.arity == 1)
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end
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defaults_hash.each do |k, v|
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_default_values[k] = DefaultValue.new(v, options)
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end
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end
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end
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end
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