Ruby-on-rails 如何检查哈希中是否存在特定值？

How to check if specific value is present in a hash?

提问by tyronegcarter

I'm using Rails and I have a hash object. I want to search the hash for a specific value. I don't know the keys associated with that value.

我正在使用 Rails 并且我有一个哈希对象。我想在哈希中搜索特定值。我不知道与该值关联的键。

How do I check if a specific value is present in a hash? Also, how do I find the key associated with that specific value?

如何检查哈希中是否存在特定值？另外，如何找到与该特定值关联的键？

回答by rkb

Hash includes Enumerable, so you can use the many methods on that module to traverse the hash. It also has this handy method:

Hash 包括Enumerable，因此您可以使用该模块上的许多方法来遍历哈希。它还有这个方便的方法：

hash.has_value?(value_you_seek)

To find the key associated with that value:

要查找与该值关联的键：

hash.key(value_you_seek)

This API documentation for Ruby (1.9.2)should be helpful.

Ruby (1.9.2) 的这个API 文档应该会有所帮助。

回答by Anton Orel

The simplest way to check multiple values are present in a hash is:

检查散列中是否存在多个值的最简单方法是：

h = { a: :b, c: :d }
h.values_at(:a, :c).all? #=> true
h.values_at(:a, :x).all? #=> false

In case you need to check also on blank values in Rails with ActiveSupport:

如果您还需要使用 ActiveSupport 检查 Rails 中的空白值：

h.values_at(:a, :c).all?(&:present?)

or

或者

h.values_at(:a, :c).none?(&:blank?)

The same in Ruby without ActiveSupport could be done by passing a block:

在没有 ActiveSupport 的 Ruby 中，同样可以通过传递一个块来完成：

h.values_at(:a, :c).all? { |i| i && !i.empty? }

回答by Val Akkapeddi

Hash.has_value?and Hash.key.

Hash.has_value？和Hash.key。

回答by d1jhoni1b

Imagine you have the following Arrayof hashes

想象一下你有以下Array哈希值

available_sports = [{name:'baseball', label:'MLB Baseball'},{name:'tackle_football', label:'NFL Football'}]

available_sports = [{name:'baseball', label:'MLB Baseball'},{name:'tackle_football', label:'NFL Football'}]

Doing something like this will do the trick

做这样的事情会成功

available_sports.any? {|h| h['name'] == 'basketball'}

available_sports.any? {|h| h['name'] == 'basketball'}

=> false

=> false

---

---

available_sports.any? {|h| h['name'] == 'tackle_football'}

available_sports.any? {|h| h['name'] == 'tackle_football'}

=> true

=> true

回答by siame

The class Hashhas the selectmethod which will return a new hash of entries for which the block is true;

该类Hash具有select方法，该方法将返回块为真的条目的新散列；

h = { "a" => 100, "b" => 200, "c" => 300 }
h.select {|k,v| v == 200}  #=> {"b" => 200}

This way you'll search by value, and get your key!

这样你就可以按值搜索，并得到你的钥匙！

回答by Subhash Chandra

While Hash#has_key?works but, as Matz wrote here, it has been deprecated in favour of Hash#key?.

虽然Hash#has_key?有效，但正如 Matz 在这里所写的那样，它已被弃用而支持Hash#key?.

Hash's key?method tells you whether a given key is present or not.

Hash的key?方法告诉您给定的键是否存在。

hash.key?(:some_key)

回答by Fellow Stranger

If you do hash.values, you now have an array.

如果你这样做hash.values，你现在有一个数组。

On arrays you can utilize the Enumerable search method include?

在数组上，您可以使用 Enumerable 搜索方法包括？

hash.values.include?(value_you_seek)

回答by hidace

An even shorter version that you could use would be hash.values

您可以使用的更短的版本是 hash.values