rules engine refactor

Author: ahanusa

Rules/field_length_rule.rb

@@ -9,8 +9,8 @@ def initialize(entity, field, length, display="")
   end
 
   def on_validate
-    @is_valid = @entity[@field].length <= @length
-    @error_message = "#{@field} must be equal to or less than #{@length} characters"
-    @is_valid 
+    if @entity[@field].length > @length
+      invalidate("#{@field} must be equal to or less than #{@length} characters")
+    end 
   end
 end

Rules/field_required_rule.rb

@@ -0,0 +1,14 @@
+require_relative '../rule_base'
+
+class FieldRequiredRule < RuleBase
+  def initialize(entity, field)
+    @entity = entity
+    @field = field
+  end
+
+  def on_validate
+    if @entity[@field].to_s.empty?
+      invalidate("#{@field} is a required field")
+    end
+  end
+end

command_base.rb

@@ -25,7 +25,7 @@ def execute
 
   def get_validation_errors
     rules =  @rules_method.call
-    errors = rules.select { |rule| rule.validate; !rule.is_valid }
+    errors = rules.select { |rule| rule.validate; !rule.valid? }
                   .map { |error| error.error_message }               
   end
 

rule_base.rb

@@ -1,47 +1,58 @@
 class RuleBase
-  attr_reader :is_valid, 
-              :error_message, 
+  attr_reader :error_message, 
               :successor, 
               :if_valid_then_execute, #The action to perform once when this rule passes validation.
               :if_invalid_then_execute #The action to perform once when this rule fails validation.
 
   def validate
+    @valid = true
     on_validate
-    if is_valid
+    if valid?
       if successor
-        successor.validate()
-        is_valid = successor.is_valid
-        error_message = successor.error_message
+        successor.validate
+        invalidate(successor.error_message) if !successor.valid?
+      end
+      if @if_valid_then_execute
+        @if_valid_then_execute.call(self)
+        @if_valid_then_execute = nil
+      end
+    else
+      if @if_invalid_then_execute
+        @if_invalid_then_execute.call(self)
+        @if_invalid_then_execute = nil
       end
-      #if @if_valid_then_execute
-        #@if_valid_then_execute.call(self)
-        #@if_valid_then_execute = nil
-      #end
-    #else
-      #if @if_invalid_then_execute
-        #@if_invalid_then_execute.call(self)
-        #@if_invalid_then_execute = nil
-      #end
     end
     return self
   end
 
+  def valid?
+    @valid
+  end
+
   def if_valid_then_validate(rule)
     @successor = rule
+    self
   end
 
-  #def if_valid_then_execute(&method)
-    #@if_valid_then_execute = method
-  #end
+  def if_valid_then_execute(method)
+    @if_valid_then_execute = method
+    self
+  end
 
-  #def if_invalid_then_execute(&method)
-    #@if_invalid_then_execute = method 
-  #end
+  def if_invalid_then_execute(method)
+    @if_invalid_then_execute = method 
+    self
+  end
 
   protected 
 
   def on_validate
     raise "on_validate must be implemented"
   end
 
+  def invalidate(message)
+    @error_message = message
+    @valid = false
+  end
+
 end

tests.rb

@@ -4,23 +4,27 @@
 require_relative "DataProxies/DatabaseProxies/customer_database_proxy"
 require_relative "DataProxies/RestfulServiceProxies/customer_restful_proxy"
 require_relative "Rules/field_length_rule"
+require_relative "Rules/field_required_rule"
 
 class CustomerService < ServiceBase
   def initialize(data_proxy)
     super(data_proxy)
   end
   def rules_for_insert(entity)
     rules = []
-    rules << FieldLengthRule.new(entity, :name, 10)
+    rules << FieldRequiredRule.new(entity, :name)
+                              .if_valid_then_execute(lambda { |rule| puts "WOOT!" })
+                              .if_valid_then_validate(FieldLengthRule.new(entity, :name, 10)
+                                                                     .if_invalid_then_execute(lambda { |rule| puts "ARGH!!" }))
     rules
   end
 end
 
-customer_data_proxy = CustomerRestfulProxy.new
-#customer_data_proxy = CustomerDatabaseProxy.new
+#customer_data_proxy = CustomerRestfulProxy.new
+customer_data_proxy = CustomerDatabaseProxy.new
 
 service = CustomerService.new(customer_data_proxy)
-result = service.insert_command({:name => "AaronHanusaa"}).execute
+result = service.insert_command({:name => "AaronHanus"}).execute
 puts result.inspect
 
 result = service.get_by_id_command(1).execute