Class: Hash

Inherits:
Object
  • Object
show all
Defined in:
lib/activerecord-update/core_ext/hash/slice.rb

Instance Method Summary collapse

Instance Method Details

#extract!(*keys) ⇒ Object

Removes and returns the key/value pairs matching the given keys.

{ a: 1, b: 2, c: 3, d: 4 }.extract!(:a, :b) # => {:a=>1, :b=>2}
{ a: 1, b: 2 }.extract!(:a, :x)             # => {:a=>1}



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# File 'lib/activerecord-update/core_ext/hash/slice.rb', line 45

def extract!(*keys)
  keys.each_with_object(self.class.new) { |key, result| result[key] = delete(key) if has_key?(key) }
end

#slice(*keys) ⇒ Object

Slices a hash to include only the given keys. Returns a hash containing the given keys.

{ a: 1, b: 2, c: 3, d: 4 }.slice(:a, :b)
# => {:a=>1, :b=>2}

This is useful for limiting an options hash to valid keys before passing to a method:

def search(criteria = {})
  criteria.assert_valid_keys(:mass, :velocity, :time)
end

search(options.slice(:mass, :velocity, :time))

If you have an array of keys you want to limit to, you should splat them:

valid_keys = [:mass, :velocity, :time]
search(options.slice(*valid_keys))



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# File 'lib/activerecord-update/core_ext/hash/slice.rb', line 21

def slice(*keys)
  keys.map! { |key| convert_key(key) } if respond_to?(:convert_key, true)
  keys.each_with_object(self.class.new) { |k, hash| hash[k] = self[k] if has_key?(k) }
end

#slice!(*keys) ⇒ Object

Replaces the hash with only the given keys. Returns a hash containing the removed key/value pairs.

{ a: 1, b: 2, c: 3, d: 4 }.slice!(:a, :b)
# => {:c=>3, :d=>4}



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# File 'lib/activerecord-update/core_ext/hash/slice.rb', line 31

def slice!(*keys)
  keys.map! { |key| convert_key(key) } if respond_to?(:convert_key, true)
  omit = slice(*self.keys - keys)
  hash = slice(*keys)
  hash.default      = default
  hash.default_proc = default_proc if default_proc
  replace(hash)
  omit
end