[英]Does Ruby have syntax for safe navigation operator of nil values, like in Groovy?
In Groovy, there is a nice syntax for working with null values. 在Groovy中,有一个很好的语法来处理null值。
For example, I can do an if statement: 例如,我可以做一个if语句:
if (obj1?.obj2?.value) {
}
This will not throw a NullPointerException even if obj1 is null (it will evaluate to false). 即使obj1为null(它将评估为false),也不会抛出NullPointerException。
This is something that's very convenient, so wondering if there is a Ruby equivalent I missed. 这是非常方便的,所以想知道我是否错过了Ruby等价物。
In a rails app there is Object#try
在rails应用程序中有
Object#try
So you can do 所以你可以做到
obj1.try(:obj2).try(:value)
or with a block (as said on comments bellow) 或者用一个块(如下面的评论所述)
obj.try {|obj| obj.value}
UPDATE UPDATE
In ruby 2.3 there is operator for this: 在ruby 2.3中有运算符:
obj&.value&.foo
Which is the same as obj && obj.value && obj.value.foo
这与
obj && obj.value && obj.value.foo
This has been added to Ruby 2.3. 这已被添加到Ruby 2.3中。
The syntax is obj1&.meth1&.meth2
. 语法是
obj1&.meth1&.meth2
。
Ruby 2.3 will have support for the safe navigation operator: Ruby 2.3将支持安全导航操作员:
obj1&.obj2&.value
https://www.ruby-lang.org/en/news/2015/11/11/ruby-2-3-0-preview1-released/ https://www.ruby-lang.org/en/news/2015/11/11/ruby-2-3-0-preview1-released/
try
was the only standard way to do this before Ruby 2.3. try
是在Ruby 2.3之前执行此操作的唯一标准方法。 With Ruby 2.3 you can do: 使用Ruby 2.3,您可以:
if obj1&.obj2&.value
end
Also, if you have a hash structure, you can use the _.
此外,如果您有哈希结构,则可以使用
_.
operator with Hashie : Hashie的运营商:
require 'hashie'
myhash = Hashie::Mash.new({foo: {bar: "blah" }})
myhash.foo.bar
=> "blah"
myhash.foo?
=> true
# use "underscore dot" for multi-level testing
myhash.foo_.bar?
=> true
myhash.foo_.huh_.what?
=> false
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