Condensing code for Hash args to the :ignore and :only options; also …

…clarifying README

CHANGELOG.md

@@ -1,5 +1,7 @@
 ## 3.0.0 (Unreleased)
 
+  - [#273](https://github.com/airblade/paper_trail/pull/273) - Make the `only` and `ignore` options accept `Hash` arguments;
+    allows for conditional tracking.
   - [#264](https://github.com/airblade/paper_trail/pull/264) - Allow unwrapped symbol to be passed in to the `on` option.
   - [#224](https://github.com/airblade/paper_trail/issues/224)/[#236](https://github.com/airblade/paper_trail/pull/236) -
     Fixed compatibility with [ActsAsTaggableOn](https://github.com/mbleigh/acts-as-taggable-on).

README.md

@@ -268,7 +268,7 @@ You can ignore changes to certain attributes like this:
 
 ```ruby
 class Article < ActiveRecord::Base
-  has_paper_trail :ignore => [:title, :rating => Proc.new { |obj| obj.raiting == 0 } ]
+  has_paper_trail :ignore => [:title, :rating]
 end
 ```
 
@@ -277,25 +277,22 @@ This means that changes to just the `title` or `rating` will not store another v
 ```ruby
 >> a = Article.create
 >> a.versions.length                         # 1
->> a.update_attributes :title => 'My Title', :rating => 0
->> a.versions.length                         # 1
 >> a.update_attributes :title => 'My Title', :rating => 3
->> a.versions.length                         # 2
->> a.previous_version.raiting                # nil
+>> a.versions.length                         # 1
 >> a.update_attributes :title => 'Greeting', :content => 'Hello'
->> a.versions.length                         # 3
+>> a.versions.length                         # 2
 >> a.previous_version.title                  # 'My Title'
 ```
 
 Or, you can specify a list of all attributes you care about:
 
 ```ruby
 class Article < ActiveRecord::Base
-  has_paper_trail :only => [:title, :author => Proc.new { |obj| obj.author.present? }]
+  has_paper_trail :only => [:title]
 end
 ```
 
-This means that only changes to the `title` and non-empty `author` will save a version of the article:
+This means that only changes to the `title` will save a version of the article:
 
 ```ruby
 >> a = Article.create
@@ -305,11 +302,31 @@ This means that only changes to the `title` and non-empty `author` will save a v
 >> a.update_attributes :content => 'Hello'
 >> a.versions.length                         # 2
 >> a.previous_version.content                # nil
->> a.update_attributes :author => 'Me'
+```
+
+The `:ignore` and `:only` options can also accept `Hash` arguments, where the :
+
+```ruby
+class Article < ActiveRecord::Base
+  has_paper_trail :only => [:title => Proc.new { |obj| !obj.title.blank? } ]
+end
+```
+
+This means that if the `title` is not blank, then only changes to the `title` will save a version of the article:
+
+```ruby
+>> a = Article.create
+>> a.versions.length                         # 1
+>> a.update_attributes :content => 'Hello'
+>> a.versions.length                         # 2
+>> a.update_attributes :title => 'My Title'
 >> a.versions.length                         # 3
->> a.update_attributes :author => ''
+>> a.update_attributes :content => 'Hai'
 >> a.versions.length                         # 3
->> a.previous_version.author                 # 'Me'
+>> a.previous_version.content                # "Hello"
+>> a.update_attributes :title => 'Dif Title'
+>> a.versions.length                         # 4
+>> a.previous_version.content                # "Hai"
 ```
 
 Passing both `:ignore` and `:only` options will result in the article being saved if a changed attribute is included in `:only` but not in `:ignore`.
@@ -973,6 +990,7 @@ Many thanks to:
 * [Bradley Priest](https://github.com/bradleypriest)
 * [David Butler](https://github.com/dwbutler)
 * [Paul Belt](https://github.com/belt)
+* [Vlad Bokov](https://github.com/razum2um)
 
 
 ## Inspirations

lib/paper_trail/has_paper_trail.rb

@@ -15,12 +15,12 @@ module ClassMethods
       #               `:create`, `:update`, `:destroy` as desired.
       # :class_name   the name of a custom Version class.  This class should inherit from Version.
       # :ignore       an array of attributes for which a new `Version` will not be created if only they change.
-      #               it can also has a Hash as an item: the key is the attribute to ignore, the value - a Proc
-      #               given a current state of object before save, only if it results in true - attribute will be ignored
+      #               it can also aceept a Hash as an argument where the key is the attribute to ignore (a `String` or `Symbol`), 
+      #               which will only be ignored if the value is a `Proc` which returns truthily.
       # :if, :unless  Procs that allow to specify conditions when to save versions for an object
       # :only         inverse of `ignore` - a new `Version` will be created only for these attributes if supplied
-      #               it can also has a Hash as an item: the key is the attribute to track, the value - a Proc
-      #               given a current state of object before save, only if it results in true - attribute will create a version
+      #               it can also aceept a Hash as an argument where the key is the attribute to track (a `String` or `Symbol`), 
+      #               which will only be counted if the value is a `Proc` which returns truthily.
       # :skip         fields to ignore completely.  As with `ignore`, updates to these fields will not create
       #               a new `Version`.  In addition, these fields will not be included in the serialized versions
       #               of the object whenever a new `Version` is created.
@@ -50,15 +50,7 @@ def has_paper_trail(options = {})
 
         [:ignore, :skip, :only].each do |k|
           paper_trail_options[k] =
-            ([paper_trail_options[k]].flatten.compact || []).map do |attr|
-              if attr.is_a? Hash
-                Hash[attr.map do |attr_name, condition|
-                  [attr_name.to_s, condition]
-                end]
-              else
-                attr.to_s
-              end
-            end
+            ([paper_trail_options[k]].flatten.compact || []).map { |attr| attr.is_a?(Hash) ? attr.stringify_keys : attr.to_s }
         end
 
         paper_trail_options[:meta] ||= {}
@@ -285,7 +277,7 @@ def item_before_change
       end
 
       def object_to_string(object)
-        _attrs = object.attributes.except(*self.class.paper_trail_options[:skip]).tap do |attributes|
+        _attrs = object.attributes.except(*self.paper_trail_options[:skip]).tap do |attributes|
           self.class.serialize_attributes_for_paper_trail attributes
         end
         PaperTrail.serializer.dump(_attrs)
@@ -296,31 +288,21 @@ def changed_notably?
       end
 
       def notably_changed
-        only = []
-        self.class.paper_trail_options[:only].each do |attr|
-          if attr.is_a? Hash
-            attr.each do |attr_name, condition|
-              only << attr_name if condition.respond_to?(:call) && condition.call(self)
-            end
-          else
-            only << attr
-          end
+        only = self.paper_trail_options[:only].dup
+        # remove Hash arguments and then evaluate whether the attributes (the keys of the hash) should also get pushed into the collection
+        only.delete_if do |obj|
+          obj.is_a?(Hash) && obj.each { |attr, condition| only << attr if condition.respond_to?(:call) && condition.call(self) }
         end
         only.empty? ? changed_and_not_ignored : (changed_and_not_ignored & only)
       end
 
       def changed_and_not_ignored
-        ignore = []
-        self.class.paper_trail_options[:ignore].each do |attr|
-          if attr.is_a? Hash
-            attr.each do |attr_name, condition|
-              ignore << attr_name if condition.respond_to?(:call) && condition.call(self)
-            end
-          else
-            ignore << attr
-          end
+        ignore = self.paper_trail_options[:ignore].dup
+         # remove Hash arguments and then evaluate whether the attributes (the keys of the hash) should also get pushed into the collection
+        ignore.delete_if do |obj|
+          obj.is_a?(Hash) && obj.each { |attr, condition| ignore << attr if condition.respond_to?(:call) && condition.call(self) }
         end
-        skip   = self.class.paper_trail_options[:skip]
+        skip = self.paper_trail_options[:skip]
         changed - ignore - skip
       end
 
@@ -329,8 +311,8 @@ def paper_trail_switched_on?
       end
 
       def save_version?
-        if_condition     = self.class.paper_trail_options[:if]
-        unless_condition = self.class.paper_trail_options[:unless]
+        if_condition     = self.paper_trail_options[:if]
+        unless_condition = self.paper_trail_options[:unless]
         (if_condition.blank? || if_condition.call(self)) && !unless_condition.try(:call, self)
       end
     end

test/dummy/app/models/article.rb

@@ -1,6 +1,6 @@
 class Article < ActiveRecord::Base
-  has_paper_trail :ignore => [:title, { :abstract => Proc.new { |obj| ['ignore abstract', 'Other abstract'].include? obj.abstract } }],
-                  :only => [:content, { :abstract => Proc.new { |obj| obj.abstract.present? } }],
+  has_paper_trail :ignore => [:title, :abstract => Proc.new { |obj| ['ignore abstract', 'Other abstract'].include? obj.abstract } ],
+                  :only => [:content, :abstract => Proc.new { |obj| obj.abstract.present? } ],
                   :skip => [:file_upload],
                   :meta => {
                               :answer => 42,