Allow keeping unmapped keys

README.md

@@ -7,7 +7,7 @@
 ## DESCRIPTION:
 
 Maps values from hashes with different structures and/or key names. Ideal for normalizing arbitrary data to be consumed by your applications, or to prepare your data for different display formats (ie. json).
- 
+
 Tiny module that allows you to easily adapt from one hash structure to another with a simple declarative DSL.
 
 ## FEATURES/PROBLEMS:
@@ -61,7 +61,7 @@ You can use HashMapper in your own little hash-like objects:
 class NiceHash
   include Enumerable
   extend HashMapper
-  
+
   map from('/names/first'), to('/first_name')
   map from('/names/last'), to('/last_name')
 
@@ -89,7 +89,7 @@ end
 
 #### Coercing values
 
-You want to make sure an incoming value gets converted to a certain type, so 
+You want to make sure an incoming value gets converted to a certain type, so
 
 ```ruby
 {'one' => '1', 'two' => '2'}
@@ -152,6 +152,51 @@ map from('/names'), to('/user') do |names|
 end
 ```
 
+#### Keeping unmapped keys as is
+
+You want unmapped keys from the input to be transmitted to the output, use the `keep_unmapped_keys` option on the `normalize` or `denormalize` methods.
+
+Usage exemple:
+```ruby
+class ManyLevels
+  extend HashMapper
+  map from('/name'),            to('/tag_attributes/name')
+  map from('/properties/type'), to('/tag_attributes/type')
+  map from('/tagid'),           to('/tag_id')
+  map from('/properties/egg'),  to('/chicken')
+end
+
+input =   {
+{
+  :name => 'ismael',
+  :tag => ["Ruby"],
+  :tagid => 1,
+  :properties => {
+    :type => 'BLAH',
+    :egg => 33,
+    :thing => "thingy"
+  }
+}
+
+ManyLevels.normalize(input, keep_unmapped_keys: true)
+
+# outputs:
+  {
+    :tag_id => 1,
+    :tag => ["Ruby"],
+    :chicken => 33,
+    :properties => {
+      :thing => "thingy"
+    },
+    :tag_attributes => {
+      :name => 'ismael',
+      :type => 'BLAH'
+    }
+  }
+```
+
+Keys `:tag` and `:properties/:thing` are kept without even being declared in the Mapper.
+
 ### Mapping in reverse
 
 Cool, you can map one hash into another, but what if I want the opposite operation?
@@ -165,9 +210,9 @@ output = NameMapper.normalize(input) # => {:first_name => 'Mark', :last_name =>
 
 NameMapper.denormalize(output) # => input
 ```
-	
+
 This will work with your block filters and even nested mappers (see below).
-	
+
 ### Advanced usage
 #### Array access
 You want:
@@ -252,7 +297,7 @@ end
 
 But HashMapper's nested mappers will actually do that for you if a value is an array, so:
 
-```ruby	
+```ruby
 map from('/employees'),	to('employees'), using: UserMapper
 ```
 ... Will map each employee using UserMapper.
@@ -268,12 +313,12 @@ They all yield a block with 2 arguments - the hash you are mapping from and the
 ```ruby
 class EggMapper
   map from('/raw'), to('/fried')
-  
+
   before_normalize do |input, output|
-    input['raw'] ||= 'please'     # this will give 'raw' a default value 
+    input['raw'] ||= 'please'     # this will give 'raw' a default value
     input
   end
-  
+
   after_denormalize do |input, output|
     output.to_a        # the denormalized object will now be an array, not a hash!!
   end
@@ -290,12 +335,12 @@ You can pass one extra argument to before and after filters if you need to:
 ```ruby
 class EggMapper
   map from('/raw'), to('/fried')
-  
+
   before_normalize do |input, output, opts|
-    input['raw'] ||= 'please' unless opts[:no_default] # this will give 'raw' a default value 
+    input['raw'] ||= 'please' unless opts[:no_default] # this will give 'raw' a default value
     input
   end
-  
+
   after_denormalize do |input, output, opts|
     output.to_a        # the denormalized object will now be an array, not a hash!!
   end
@@ -306,7 +351,7 @@ EggMapper.normalize({}, no_default: true)
 EggMapper.denormalize({fried: 4})
 ```
 
-   
+
 ## REQUIREMENTS:
 
 ## TODO:

hash_mapper.gemspec

@@ -8,7 +8,7 @@ Gem::Specification.new do |s|
   s.authors     = ['Ismael Celis']
   s.description = %q{Tiny module that allows you to easily adapt from one hash structure to another with a simple declarative DSL.}
   s.email       = %q{ismaelct@gmail.com}
-  
+
   s.files         = `git ls-files`.split("\n")
   s.homepage      = %q{http://github.com/ismasan/hash_mapper}
   s.rdoc_options  = ['--charset=UTF-8']
@@ -17,13 +17,15 @@ Gem::Specification.new do |s|
   s.test_files    = `git ls-files -- {test,spec,features}/*`.split("\n")
   s.executables   = `git ls-files -- bin/*`.split("\n").map{ |f| File.basename(f) }
   s.require_paths = ['lib']
-  
+
   if Gem::Version.new(Gem::VERSION) >= Gem::Version.new('1.2.0') then
     s.add_runtime_dependency("activesupport", ">= 4")
+    s.add_runtime_dependency("ruby_dig")
   else
     s.add_dependency("activesupport", ">= 4")
+    s.add_dependency("ruby_dig")
   end
-  
+
   # specify any dependencies here; for example:
   s.add_development_dependency 'rspec'
   s.add_development_dependency 'rake'

lib/hash_mapper.rb

@@ -1,4 +1,5 @@
 require 'hash_mapper/version'
+require 'ruby_dig'
 
 $:.unshift(File.dirname(__FILE__)) unless
 $:.include?(File.dirname(__FILE__)) || $:.include?(File.expand_path(File.dirname(__FILE__)))
@@ -7,6 +8,9 @@ def require_active_support
   require 'active_support/core_ext/array/extract_options'
   require 'active_support/core_ext/hash/indifferent_access'
   require 'active_support/core_ext/object/duplicable'
+  require 'active_support/core_ext/object/deep_dup'
+  require 'active_support/core_ext/object/blank'
+  require 'active_support/core_ext/hash/deep_merge'
   require 'active_support/core_ext/class/attribute'
 end
 
@@ -101,6 +105,7 @@ def after_denormalize(&blk)
 
   def perform_hash_mapping(a_hash, meth, opts)
     output = {}
+    a_hash = a_hash.deep_dup
 
     # Before filters
     a_hash = self.send(:"before_#{meth}_filters").inject(a_hash) do |memo, filter|
@@ -109,13 +114,41 @@ def perform_hash_mapping(a_hash, meth, opts)
 
     # Do the mapping
     self.maps.each do |m|
-      m.process_into(output, a_hash, meth)
+      m.process_into(output, a_hash, meth, opts)
     end
 
     # After filters
-    self.send(:"after_#{meth}_filters").inject(output) do |memo, filter|
+    output = self.send(:"after_#{meth}_filters").inject(output) do |memo, filter|
       filter.call(a_hash, memo, opts)
     end
+
+    output = merge_hashes(output, a_hash, meth) if opts[:keep_unmapped_keys]
+
+    output
+  end
+
+  def merge_hashes(output, dupped_hash, meth)
+    clean_dup(dupped_hash, meth).deep_merge(output)
+  end
+
+  def clean_dup(dupped_hash, meth)
+    self.maps.each do |m|
+      segments = meth == :normalize ? m.path_from.segments.dup : m.path_to.segments.dup
+      key = segments.pop
+      digged_hash(dupped_hash, segments).delete(key)
+    end
+    clean(dupped_hash)
+  end
+
+  def clean(hash)
+    return unless hash.is_a?(Hash)
+    hash.keys.each { |k| clean(hash[k]) }
+    hash.delete_if { |_, v| v.blank? }
+  end
+
+  def digged_hash(hash, segments)
+    return hash if segments.empty?
+    hash.dig(*segments) || {}
   end
 
   # Contains PathMaps
@@ -132,14 +165,14 @@ def initialize(path_from, path_to, options = {})
       @default_value = options.fetch(:default, :hash_mapper_no_default)
     end
 
-    def process_into(output, input, meth = :normalize)
+    def process_into(output, input, meth = :normalize, opts)
       path_1, path_2 = (meth == :normalize ? [path_from, path_to] : [path_to, path_from])
-      value = get_value_from_input(output, input, path_1, meth)
+      value = get_value_from_input(output, input, path_1, meth, opts)
       set_value_in_output(output, path_2, value)
     end
     protected
 
-    def get_value_from_input(output, input, path, meth)
+    def get_value_from_input(output, input, path, meth, opts)
       value = path.inject(input) do |h,e|
         if h.is_a?(Hash)
           v = [h[e.to_sym], h[e.to_s]].compact.first
@@ -149,7 +182,7 @@ def get_value_from_input(output, input, path, meth)
         return :hash_mapper_no_value if v.nil?
         v
       end
-      delegated_mapper ? delegate_to_nested_mapper(value, meth) : value
+      delegated_mapper ? delegate_to_nested_mapper(value, meth, opts) : value
     end
 
     def set_value_in_output(output, path, value)
@@ -163,14 +196,14 @@ def set_value_in_output(output, path, value)
       add_value_to_hash!(output, path, value)
     end
 
-    def delegate_to_nested_mapper(value, meth)
+    def delegate_to_nested_mapper(value, meth, opts)
       case value
       when Array
-        value.map {|h| delegated_mapper.send(meth, h)}
+        value.map {|h| delegated_mapper.send(meth, h, opts)}
       when nil
         return :hash_mapper_no_value
       else
-        delegated_mapper.send(meth, value)
+        delegated_mapper.send(meth, value, opts)
       end
     end
 
@@ -190,9 +223,7 @@ def add_value_to_hash!(hash, path, value)
           end
         end
       end
-
     end
-
   end
 
   # contains array of path segments
@@ -246,7 +277,5 @@ def parse(path)
       end.flatten
       segments
     end
-
   end
-
 end