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method

try

Importance_4
v3.1.0 - Show latest stable - 4 notes - Class: Object
try(*a, &b) public

Invokes the method identified by the symbol method, passing it any arguments and/or the block specified, just like the regular Ruby Object#send does.

Unlike that method however, a NoMethodError exception will not be raised and nil will be returned instead, if the receiving object is a nil object or NilClass.

If try is called without a method to call, it will yield any given block with the object.

Examples

Without try

@person && @person.name

or

@person ? @person.name : nil

With try

@person.try(:name)

try also accepts arguments and/or a block, for the method it is trying

Person.try(:find, 1)
@people.try(:collect) {|p| p.name}

Without a method argument try will yield to the block unless the receiver is nil.

@person.try { |p| "#{p.first_name} #{p.last_name}" }
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January 6, 2010
3 thanks

Doesn't return nil if the object you try from isn't nil.

Note that this doesn’t prevent a NoMethodError if you attempt to call a method that doesn’t exist on a valid object.

a = Article.new

a.try(:author) #=> #<Author ...>

nil.try(:doesnt_exist) #=> nil

a.try(:doesnt_exist) #=> NoMethodError: undefined method `doesnt_exist' for #<Article:0x106c7d5d8>

This is on Ruby 1.8.7 patchlevel 174

June 10, 2009
2 thanks

[:a, :b, :c].try([1]) ? The answer is No.

Correct way is this:

[:a, :b, :c].try(:at, 1)
January 6, 2010
0 thanks

Alternative:

without using at

[:a, :b, :c].try(:[], 1)
July 24, 2012
0 thanks

rest of code is in NilClass#try

If you click “Show source” here, you may get confused. The logic for #try is shared between this method and NilClass#try . Both versions are currently implemented in the file activesupport/lib/active_support/core_ext/object/try.rb .