instance method
set_callback
Ruby on Rails 5.1.7
Since v3.0.20Signature
set_callback(name, *filter_list, &block)Install a callback for the given event.
set_callback :save, :before, :before_method
set_callback :save, :after, :after_method, if: :condition
set_callback :save, :around, ->(r, block) { stuff; result = block.call; stuff }
The second argument 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_method
The callback can be specified as a symbol naming an instance method; as a proc, lambda, or block; 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, a string (deprecated) or an array of symbols, each naming an instance method or a proc; the callback will be called only when they all return a true value. -
:unless- A symbol, a string (deprecated) or an array of symbols, each naming an instance method or a proc; the callback will be called only when they all return a false value. -
:prepend- Iftrue, the callback will be prepended to the existing chain rather than appended.
Parameters
-
namereq -
filter_listrest -
blockblock
Source
# File activesupport/lib/active_support/callbacks.rb, line 662
def set_callback(name, *filter_list, &block)
type, filters, options = normalize_callback_params(filter_list, block)
if options[:if].is_a?(String) || options[:unless].is_a?(String)
ActiveSupport::Deprecation.warn(<<-MSG.squish)
Passing string to be evaluated in :if and :unless conditional
options is deprecated and will be removed in Rails 5.2 without
replacement. Pass a symbol for an instance method, or a lambda,
proc or block, instead.
MSG
end
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 662
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Defined in ActiveSupport::Callbacks::ClassMethods