Add support for specifying a custom audit model via the audited options

README.md

@@ -425,6 +425,24 @@ Audited.config do |config|
 end
 ```
 
+### Multiple `Audit` models
+
+If you want to use a different audit model for a specfic audited model, create a new class that
+inherits from `Audited::Audit`:
+```ruby
+class CustomAudit < Audited::Audit
+  def some_custom_behavior
+    "Hiya!"
+  end
+end
+```
+Then provide the class name in options:
+```ruby
+class User < ActiveRecord::Base
+  audited class_name: "CustomAudit"
+end
+```
+
 ### Enum Storage
 
 In 4.10, the default behavior for enums changed from storing the value synthesized by Rails to the value stored in the DB. You can restore the previous behavior by setting the store_synthesized_enums configuration value:

lib/audited.rb

@@ -18,13 +18,20 @@ class << self
       :store_synthesized_enums
     attr_writer :audit_class
 
-    def audit_class
+    def default_audit_class
       # The audit_class is set as String in the initializer. It can not be constantized during initialization and must
       # be constantized at runtime. See https://github.com/collectiveidea/audited/issues/608
       @audit_class = @audit_class.safe_constantize if @audit_class.is_a?(String)
       @audit_class ||= Audited::Audit
     end
 
+    def audit_class(custom_class_name = nil)
+      if custom_class_name.is_a?(String)
+        return custom_class_name.safe_constantize || default_audit_class
+      end
+      default_audit_class
+    end
+
     # remove audit_model in next major version it was only shortly present in 5.1.0
     alias_method :audit_model, :audit_class
     deprecate audit_model: "use Audited.audit_class instead of Audited.audit_model. This method will be removed.",

lib/audited/auditor.rb

@@ -83,8 +83,8 @@ def set_audit(options)
           before_destroy :require_comment if audited_options[:on].include?(:destroy)
         end
 
-        has_many :audits, -> { order(version: :asc) }, as: :auditable, class_name: Audited.audit_class.name, inverse_of: :auditable
-        Audited.audit_class.audited_class_names << to_s
+        has_many :audits, -> { order(version: :asc) }, as: :auditable, class_name: Audited.audit_class(audited_options[:class_name]).name, inverse_of: :auditable
+        Audited.audit_class(audited_options[:class_name]).audited_class_names << to_s
 
         after_create :audit_create if audited_options[:on].include?(:create)
         before_update :audit_update if audited_options[:on].include?(:update)
@@ -102,7 +102,7 @@ def set_audit(options)
       end
 
       def has_associated_audits
-        has_many :associated_audits, as: :associated, class_name: Audited.audit_class.name
+        has_many :associated_audits, as: :associated, class_name: Audited.audit_class(audited_options[:class_name]).name
       end
 
       def update_audited_options(new_options)
@@ -176,14 +176,14 @@ def revisions(from_version = 1)
       # Returns nil for versions greater than revisions count
       def revision(version)
         if version == :previous || audits.last.version >= version
-          revision_with Audited.audit_class.reconstruct_attributes(audits_to(version))
+          revision_with Audited.audit_class(audited_options[:class_name]).reconstruct_attributes(audits_to(version))
         end
       end
 
       # Find the oldest revision recorded prior to the date/time provided.
       def revision_at(date_or_time)
         audits = self.audits.up_until(date_or_time)
-        revision_with Audited.audit_class.reconstruct_attributes(audits) unless audits.empty?
+        revision_with Audited.audit_class(audited_options[:class_name]).reconstruct_attributes(audits) unless audits.empty?
       end
 
       # List of attributes that are audited.
@@ -196,8 +196,8 @@ def audited_attributes
 
       # Returns a list combined of record audits and associated audits.
       def own_and_associated_audits
-        Audited.audit_class.unscoped.where(auditable: self)
-          .or(Audited.audit_class.unscoped.where(associated: self))
+        Audited.audit_class(audited_options[:class_name]).unscoped.where(auditable: self)
+          .or(Audited.audit_class(audited_options[:class_name]).unscoped.where(associated: self))
           .order(created_at: :desc)
       end
 
@@ -229,7 +229,7 @@ def revision_with(attributes)
           revision.send :instance_variable_set, "@destroyed", false
           revision.send :instance_variable_set, "@_destroyed", false
           revision.send :instance_variable_set, "@marked_for_destruction", false
-          Audited.audit_class.assign_revision_attributes(revision, attributes)
+          Audited.audit_class(audited_options[:class_name]).assign_revision_attributes(revision, attributes)
 
           # Remove any association proxies so that they will be recreated
           # and reference the correct object for this revision. The only way
@@ -508,7 +508,7 @@ def enable_auditing
       # convenience wrapper around
       # @see Audit#as_user.
       def audit_as(user, &block)
-        Audited.audit_class.as_user(user, &block)
+        Audited.audit_class(audited_options[:class_name]).as_user(user, &block)
       end
 
       def auditing_enabled