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To add a new pair to Hash I do:
{:a => 1, :b => 2}.merge!({:c => 3}) #=> {:a => 1, :b => 2, :c => 3} Is there a similar way to delete a key from Hash ?
This works:
{:a => 1, :b => 2}.reject! { |k| k == :a } #=> {:b => 2} but I would expect to have something like:
{:a => 1, :b => 2}.delete!(:a) #=> {:b => 2} It is important that the returning value will be the remaining hash, so I could do things like:
foo(my_hash.reject! { |k| k == my_key }) in one line.
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hash.fetch(key) { | key | block } Returns a value from hash for the given key. If the key can't be found, and there are no other arguments, it raises an IndexError exception; if default is given, it is returned; if the optional block is specified, its result is returned.
The contents of a certain hash can be replaced in Ruby by using the replace() method. It replaces the entire contents of a hash with the contents of another hash.
Overview. We can check if a particular hash contains a particular key by using the method has_key?(key) . It returns true or false depending on whether the key exists in the hash or not.
Rails has an except/except! method 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 If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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