Allow proc in validatation conditionals

Author: aviscasillas

motion/validatable.rb

@@ -130,8 +130,21 @@ def validate_for(field, value)
       result
     end
 
+    def must_validate?(validation)
+      stuff = validation[:if]
+      return true unless stuff
+
+      case stuff
+      when Symbol then send(stuff)
+      when Proc then instance_exec(&stuff)
+      else
+        fail ArgumentError,
+             ':if requires a Symbol denoting a method or a Proc/lambda'
+      end
+    end
+
     def validate_one(field, validation) #nodoc
-      return true unless validation[:if] ? send(validation[:if]) : true
+      return true unless must_validate?(validation)
 
       result = true
       validation.each_pair do |validation_type, setting|

spec/validation_spec.rb

@@ -7,7 +7,8 @@ class ValidatableTask
                 :some_day => :string,
                 :some_float => :float,
                 :some_int => :int,
-                :not_validate => :string
+                :if_with_proc => :string,
+                :if_with_sym => :string
 
   validate      :name, :presence => true
   validate      :name, :length => 2..10
@@ -16,7 +17,8 @@ class ValidatableTask
   validate      :some_day, :length => 8..10
   validate      :some_float, :presence => true
   validate      :some_int, :presence => true
-  validate      :not_validate, :presence => true, :if => :false_condition_method
+  validate      :if_with_proc, :presence => true, :if => -> { if_with_proc == 'unexpected' }
+  validate      :if_with_sym, :presence => true, :if => :false_condition_method
 
   def false_condition_method
     false
@@ -31,14 +33,24 @@ def false_condition_method
       :some_day => '12-12-12',
       :some_float => 1.080,
       :some_int => 99,
-      :not_validate => 'Never validated column'
+      :if_with_proc => 'Never validated column',
+      :if_with_sym => 'Never validated column'
     }
   end
 
   describe 'conditional validation' do
-    it 'does not validate if condition method returns false' do
-      task = ValidatableTask.new(@valid_tasks.except(:not_validate))
-      task.valid?.should == true
+    context 'with conditional by method' do
+      it 'does not validate if condition returns false' do
+        task = ValidatableTask.new(@valid_tasks.except(:if_with_sym))
+        task.valid?.should == true
+      end
+    end
+
+    context 'with conditional by proc' do
+      it 'does not validate if condition returns false' do
+        task = ValidatableTask.new(@valid_tasks.except(:if_with_proc))
+        task.valid?.should == true
+      end
     end
   end