instance method `set_callback`

Ruby on Rails 4.1.16

Since v3.0.20

Available in: v3.0.20 v3.1.12 v3.2.22.5 v4.0.13 v4.1.16 v4.2.9 v5.2.8.1 v6.0.6 v6.1.7.10 v7.0.10 v7.1.6 v7.2.3 v8.0.4 v8.1.2

Compare with:

set_callback(name, *filter_list, &block)

Install a callback for the given event.

set_callback :save, :before, :before_meth
set_callback :save, :after,  :after_meth, if: :condition
set_callback :save, :around, ->(r, &block) { stuff; result = block.call; stuff }

The second arguments indicates whether the callback is to be run :before, :after, or :around the event. If omitted, :before is assumed. This means the first example above can also be written as:

set_callback :save, :before_meth

The callback can be specified as a symbol naming an instance method; as a proc, lambda, or block; as a string to be instance evaluated; or as an object that responds to a certain method determined by the :scope argument to define_callbacks.

If a proc, lambda, or block is given, its body is evaluated in the context of the current object. It can also optionally accept the current object as an argument.

Before and around callbacks are called in the order that they are set; after callbacks are called in the reverse order.

Around callbacks can access the return value from the event, if it wasn’t halted, from the yield call.

Options

:if - A symbol naming an instance method or a proc; the callback will be called only when it returns a true value.
:unless - A symbol naming an instance method or a proc; the callback will be called only when it returns a false value.
:prepend - If true, the callback will be prepended to the existing chain rather than appended.

Parameters

name req
filter_list rest
block block

Source

# File activesupport/lib/active_support/callbacks.rb, line 642
      def set_callback(name, *filter_list, &block)
        type, filters, options = normalize_callback_params(filter_list, block)
        self_chain = get_callbacks name
        mapped = filters.map do |filter|
          Callback.build(self_chain, filter, type, options)
        end

        __update_callbacks(name) do |target, chain|
          options[:prepend] ? chain.prepend(*mapped) : chain.append(*mapped)
          target.set_callbacks name, chain
        end
      end

Defined in activesupport/lib/active_support/callbacks.rb line 642 · View on GitHub · Improve this page · Find usages on GitHub

Defined in ActiveSupport::Callbacks::ClassMethods

Signature

Options

Parameters