diff options
| -rw-r--r-- | activesupport/CHANGELOG.md | 2 | ||||
| -rw-r--r-- | activesupport/lib/active_support/core_ext/hash/keys.rb | 43 | ||||
| -rw-r--r-- | activesupport/test/core_ext/hash_ext_test.rb | 15 | ||||
| -rw-r--r-- | guides/source/active_support_core_extensions.textile | 32 |
4 files changed, 74 insertions, 18 deletions
diff --git a/activesupport/CHANGELOG.md b/activesupport/CHANGELOG.md index dace2f81f5..b2bacde799 100644 --- a/activesupport/CHANGELOG.md +++ b/activesupport/CHANGELOG.md @@ -1,5 +1,7 @@ ## Rails 4.0.0 (unreleased) ## +* Add `Hash#transform_keys` and `Hash#transform_keys!`. *Mark McSpadden* + * Changed xml type `datetime` to `dateTime` (with upper case letter `T`). *Angelo Capilleri* * Add `:instance_accessor` option for `class_attribute`. *Alexey Vakhov* diff --git a/activesupport/lib/active_support/core_ext/hash/keys.rb b/activesupport/lib/active_support/core_ext/hash/keys.rb index be4d611ce7..8b24ef3350 100644 --- a/activesupport/lib/active_support/core_ext/hash/keys.rb +++ b/activesupport/lib/active_support/core_ext/hash/keys.rb @@ -1,46 +1,53 @@ class Hash - # Return a new hash with all keys converted to strings. + # Return a new hash with all keys converted using the block operation. # - # { :name => 'Rob', :years => '28' }.stringify_keys - # #=> { "name" => "Rob", "years" => "28" } - def stringify_keys + # { :name => 'Rob', :years => '28' }.transform_keys{ |key| key.to_s.upcase } + # # => { "NAME" => "Rob", "YEARS" => "28" } + def transform_keys result = {} keys.each do |key| - result[key.to_s] = self[key] + result[yield(key)] = self[key] end result end - # Destructively convert all keys to strings. Same as - # +stringify_keys+, but modifies +self+. - def stringify_keys! + # Destructively convert all keys using the block operations. + # Same as transform_keys but modifies +self+ + def transform_keys! keys.each do |key| - self[key.to_s] = delete(key) + self[yield(key)] = delete(key) end self end + # Return a new hash with all keys converted to strings. + # + # { :name => 'Rob', :years => '28' }.stringify_keys + # #=> { "name" => "Rob", "years" => "28" } + def stringify_keys + transform_keys{ |key| key.to_s } + end + + # Destructively convert all keys to strings. Same as + # +stringify_keys+, but modifies +self+. + def stringify_keys! + transform_keys!{ |key| key.to_s } + end + # Return a new hash with all keys converted to symbols, as long as # they respond to +to_sym+. # # { 'name' => 'Rob', 'years' => '28' }.symbolize_keys # #=> { :name => "Rob", :years => "28" } def symbolize_keys - result = {} - keys.each do |key| - result[(key.to_sym rescue key)] = self[key] - end - result + transform_keys{ |key| key.to_sym rescue key } end alias_method :to_options, :symbolize_keys # Destructively convert all keys to symbols, as long as they respond # to +to_sym+. Same as +symbolize_keys+, but modifies +self+. def symbolize_keys! - keys.each do |key| - self[(key.to_sym rescue key)] = delete(key) - end - self + transform_keys!{ |key| key.to_sym rescue key } end alias_method :to_options!, :symbolize_keys! diff --git a/activesupport/test/core_ext/hash_ext_test.rb b/activesupport/test/core_ext/hash_ext_test.rb index 0b0e7da4a5..b13ee4c9ff 100644 --- a/activesupport/test/core_ext/hash_ext_test.rb +++ b/activesupport/test/core_ext/hash_ext_test.rb @@ -28,10 +28,13 @@ class HashExtTest < ActiveSupport::TestCase @mixed = { :a => 1, 'b' => 2 } @fixnums = { 0 => 1, 1 => 2 } @illegal_symbols = { [] => 3 } + @upcase_strings = { 'A' => 1, 'B' => 2 } end def test_methods h = {} + assert_respond_to h, :transform_keys + assert_respond_to h, :transform_keys! assert_respond_to h, :symbolize_keys assert_respond_to h, :symbolize_keys! assert_respond_to h, :stringify_keys @@ -40,6 +43,18 @@ class HashExtTest < ActiveSupport::TestCase assert_respond_to h, :to_options! end + def test_transform_keys + assert_equal @upcase_strings, @strings.transform_keys{ |key| key.to_s.upcase } + assert_equal @upcase_strings, @symbols.transform_keys{ |key| key.to_s.upcase } + assert_equal @upcase_strings, @mixed.transform_keys{ |key| key.to_s.upcase } + end + + def test_transform_keys! + assert_equal @upcase_strings, @symbols.dup.transform_keys!{ |key| key.to_s.upcase } + assert_equal @upcase_strings, @strings.dup.transform_keys!{ |key| key.to_s.upcase } + assert_equal @upcase_strings, @mixed.dup.transform_keys!{ |key| key.to_s.upcase } + end + def test_symbolize_keys assert_equal @symbols, @symbols.symbolize_keys assert_equal @symbols, @strings.symbolize_keys diff --git a/guides/source/active_support_core_extensions.textile b/guides/source/active_support_core_extensions.textile index 80faffa49c..1f92d9d5f5 100644 --- a/guides/source/active_support_core_extensions.textile +++ b/guides/source/active_support_core_extensions.textile @@ -2549,6 +2549,38 @@ There's also the bang variant +except!+ that removes keys in the very receiver. NOTE: Defined in +active_support/core_ext/hash/except.rb+. +h5. +transform_keys+ and +transform_keys!+ + +The method +transform_keys+ accepts a block and returns a hash that has applied the block operations to each of the keys in the receiver: + +<ruby> +{nil => nil, 1 => 1, :a => :a}.transform_keys{ |key| key.to_s.upcase } +# => {"" => nil, "A" => :a, "1" => 1} +</ruby> + +The result in case of collision is undefined: + +<ruby> +{"a" => 1, :a => 2}.transform_keys{ |key| key.to_s.upcase } +# => {"A" => 2}, in my test, can't rely on this result though +</ruby> + +This method may be useful for example to build specialized conversions. For instance +stringify_keys+ and +symbolize_keys+ use +transform_keys+ to perform their key conversions: + +<ruby> +def stringify_keys + transform_keys{ |key| key.to_s } +end +... +def symbolize_keys + transform_keys{ |key| key.to_sym rescue key } +end +</ruby> + +There's also the bang variant +transform_keys!+ that applies the block operations to keys in the very receiver. + +NOTE: Defined in +active_support/core_ext/hash/keys.rb+. + h5. +stringify_keys+ and +stringify_keys!+ The method +stringify_keys+ returns a hash that has a stringified version of the keys in the receiver. It does so by sending +to_s+ to them: |