How to check if a specific key is present in a hash or not

Question

I want to check whether the  user  key is present or not in the session hash  How can I do this   Note that I don t want to check whether the key s value is nil or not  I just want to check whether the  user  key is present

User · Answer

You can always use Hash key  to check if the key is present in a hash or not    If not it will return you false  hash      one  1  two 2    hash key   one     gt  true  hash key   four     gt  false

User · Answer

In latest Ruby versions Hash instance has a key  method    a  1  key   a    gt  true   Be sure to use the symbol key or a string key depending on what you have in your hash     a    gt  2  key   a    gt  false

User · Answer

Hash s key  method tells you whether a given key is present or not   session key   user

User · Answer

You can use    hash keys include  key  irb main  001 0 gt  hash     quot pot quot    gt  1   quot tot quot    gt  2   quot not quot    gt  3    gt    quot pot quot   gt 1   quot tot quot   gt 2   quot not quot   gt 3  irb main  002 0 gt  key    quot not quot    gt   quot not quot  irb main  003 0 gt  hash keys include  key    gt  true

User · Answer

Another way is here  hash    one  1  two  2   hash member   one     gt  true  hash member   five     gt  false

User · Answer

It is very late but preferably symbols should be used as key   my hash      my hash  my key     value   my hash has key   my key      gt  false  my hash has key   my key  to sym     gt  true   my hash2      my hash2  my key      value   my hash2 has key   my key      gt  true  my hash2 has key   my key  to sym     gt  false    But when creating hash if you pass string as key then it will search for the string in keys   But when creating hash you pass symbol as key then has key  will search the keys by using symbol     If you are using Rails  you can use Hash with indifferent access to avoid this  both hash  my key  and hash  my key   will point to the same record

User · Answer

While Hash has key  gets the job done  as Matz notes here  it has been deprecated in favour of Hash key    hash key  some key

User · Answer

In Rails 5  the has key  method checks if key exists in hash  The syntax to use it is   YourHash has key   yourkey

[ruby] How to check if a specific key is present in a hash or not?

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