How to remove a key from Hash and get the remaining hash in Ruby/Rails?

It's was great if delete return the delete pair of the hash.
I'm doing this:

hash = {a: 1, b: 2, c: 3}
{b: hash.delete(:b)} # => {:b=>2}
hash # => {:a=>1, :c=>3}

Multiple ways to delete Key in Hash.
you can use any Method from below

hash = {a: 1, b: 2, c: 3}
hash.except!(:a) # Will remove *a* and return HASH
hash # Output :- {b: 2, c: 3}

hash = {a: 1, b: 2, c: 3}
hash.delete(:a) # will remove *a* and return 1 if *a* not present than return nil

So many ways is there, you can look on Ruby doc of Hash [here](

[To see links please register here]

).

Thank you

There are many ways to remove a key from a hash and get the remaining hash in Ruby.

1. `.slice` => It will return selected keys and not delete them from the original hash. Use `slice!` if you want to remove the keys permanently else use simple `slice`.

2.2.2 :074 > hash = {"one"=>1, "two"=>2, "three"=>3}
=> {"one"=>1, "two"=>2, "three"=>3}
2.2.2 :075 > hash.slice("one","two")
=> {"one"=>1, "two"=>2}
2.2.2 :076 > hash
=> {"one"=>1, "two"=>2, "three"=>3}

2. `.delete` => It will delete the selected keys from the original hash(it can accept only one key and not more than one).

2.2.2 :094 > hash = {"one"=>1, "two"=>2, "three"=>3}
=> {"one"=>1, "two"=>2, "three"=>3}
2.2.2 :095 > hash.delete("one")
=> 1
2.2.2 :096 > hash
=> {"two"=>2, "three"=>3}

3. `.except` => It will return the remaining keys but not delete anything from the original hash. Use `except!` if you want to remove the keys permanently else use simple `except`.

2.2.2 :097 > hash = {"one"=>1, "two"=>2, "three"=>3}
=> {"one"=>1, "two"=>2, "three"=>3}
2.2.2 :098 > hash.except("one","two")
=> {"three"=>3}
2.2.2 :099 > hash
=> {"one"=>1, "two"=>2, "three"=>3}


4. `.delete_if` => In case you need to remove a key based on a value. It will obviously remove the matching keys from the original hash.

2.2.2 :115 > hash = {"one"=>1, "two"=>2, "three"=>3, "one_again"=>1}
=> {"one"=>1, "two"=>2, "three"=>3, "one_again"=>1}
2.2.2 :116 > value = 1
=> 1
2.2.2 :117 > hash.delete_if { |k,v| v == value }
=> {"two"=>2, "three"=>3}
2.2.2 :118 > hash
=> {"two"=>2, "three"=>3}

5. `.compact` => It is used to remove all `nil` values from the hash. Use `compact!` if you want to remove the `nil` values permanently else use simple `compact`.

2.2.2 :119 > hash = {"one"=>1, "two"=>2, "three"=>3, "nothing"=>nil, "no_value"=>nil}
=> {"one"=>1, "two"=>2, "three"=>3, "nothing"=>nil, "no_value"=>nil}
2.2.2 :120 > hash.compact
=> {"one"=>1, "two"=>2, "three"=>3}

Results based on Ruby 2.2.2.

Try the `except!` method.

{:a => 1, :b => 2}.except!(:a) #=> {:b => 2}

Why not just use:

hash.delete(key)

`hash` is now the "remaining hash" you're looking for.

## Hash#except (Ruby 3.0+)

Starting from Ruby 3.0, [Hash#except](

[To see links please register here]

) is a build-in method.

As a result, there is no more need to depend on ActiveSupport or write monkey-patches in order to use it.

```ruby
h = { a: 1, b: 2, c: 3 }
p h.except(:a) #=> {:b=>2, :c=>3}
```

**Sources:**

- [Hash#except](

[To see links please register here]

) from official Ruby docs.
- [Link to the PR](

[To see links please register here]

).
- [Ruby 3.0 adds Hash#except and ENV.except](

[To see links please register here]

).

For those of you who just came here to know how to delete a key/value pair from a hash, you can use:<br>
`hash.delete(key)`

For the rest of you who came here to read a wall of text about something entirely different, you can read the rest of this answer:

[Rails has an except/except! method][1] that returns the hash with those keys removed. If you're already using Rails, there's no sense in creating your own version of this.

class Hash
# Returns a hash that includes everything but the given keys.
# hash = { a: true, b: false, c: nil}
# hash.except(:c) # => { a: true, b: false}
# hash # => { a: true, b: false, c: nil}
#
# This is useful for limiting a set of parameters to everything but a few known toggles:
# @person.update(params[:person].except(:admin))
def except(*keys)
dup.except!(*keys)
end

# Replaces the hash without the given keys.
# hash = { a: true, b: false, c: nil}
# hash.except!(:c) # => { a: true, b: false}
# hash # => { a: true, b: false }
def except!(*keys)
keys.each { |key| delete(key) }
self
end
end

[1]:

[To see links please register here]

Use `delete`, `except`, or `except!`

`sample_hash = {hey: 'hey', hello: 'hello'}`

Delete:
```
sample_hash.delete(:hey)
=> 'hey'

sample_hash
=> {hello: 'hello'}
```
Returns value of the key and deletes the key in the original object, returns nil if no such key

Except:
```
sample_hash.except(:hey)
=> {hello: 'hello'}

sample_hash
=> {hey: 'hey', hello: 'hello'}
```
Returns the entire hash without the specified keys, but does not update the original hash

Except!:
`except!` is the same as except but it permanently changes the state of the original hash like all bang operated methods do

```
sample_hash.except!(:hey)
=> {hello: 'hello'}

sample_hash
=> {hello: 'hello'}
```