class Object
Borrowed and modified from {github.com/rails/rails/blob/master/activesupport/lib/active_support/core_ext/object/blank.rb}
Borrowed and modified from {github.com/rails/rails/blob/master/activesupport/lib/active_support/core_ext/object/try.rb}
Public Instance Methods
An object is blank if it's false, empty, or a whitespace string. For example, '', ' ', nil
, [], and {} are all blank.
This simplifies:
if address.nil? || address.empty?
…to:
if address.blank?
# File lib/buff/extensions/object/blank.rb, line 15 def blank? respond_to?(:empty?) ? empty? : !self end
Returns object if it's present?
otherwise returns nil
. object.presence
is equivalent to object.present? ? object : nil
.
This is handy for any representation of objects where blank is the same as not present at all. For example, this simplifies a common check for HTTP POST/query parameters:
state = params[:state] if params[:state].present? country = params[:country] if params[:country].present? region = state || country || 'US'
…becomes:
region = params[:state].presence || params[:country].presence || 'US'
# File lib/buff/extensions/object/blank.rb, line 38 def presence self if present? end
An object is present if it's not blank?
.
# File lib/buff/extensions/object/blank.rb, line 20 def present? !blank? end
Invokes the public method whose name goes as first argument just like public_send
does, except that if the receiver does not respond to it the call returns nil
rather than raising an exception.
This method is defined to be able to write
@person.try(:name)
instead of
@person ? @person.name : nil
try
returns nil
when called on nil
regardless of whether it responds to the method:
nil.try(:to_i) # => nil, rather than 0
Arguments and blocks are forwarded to the method if invoked:
@posts.try(:each_slice, 2) do |a, b| ... end
The number of arguments in the signature must match. If the object responds to the method the call is attempted and ArgumentError
is still raised otherwise.
If try
is called without arguments it yields the receiver to a given block unless it is nil
:
@person.try do |p| ... end
Please also note that try
is defined on Object
, therefore it won't work with instances of classes that do not have Object
among their ancestors, like direct subclasses of BasicObject
. For example, using try
with SimpleDelegator
will delegate try
to the target instead of calling it on delegator itself.
# File lib/buff/extensions/object/try.rb, line 44 def try(*a, &b) if a.empty? && block_given? yield self else public_send(*a, &b) if respond_to?(a.first) end end
Same as try
, but will raise a NoMethodError exception if the receiving is not nil and does not implemented the tried method.
# File lib/buff/extensions/object/try.rb, line 54 def try!(*a, &b) if a.empty? && block_given? yield self else public_send(*a, &b) end end