Move validation check to thread local to avoid infinite loops.

- Instance variables not safe since reload breaks bindings.
- Fixes #1151.

lib/mongoid/relations/accessors.rb

@@ -121,7 +121,8 @@ def getter(name, metadata)
         def setter(name, metadata)
           tap do
             define_method("#{name}=") do |object|
-              if relation_exists?(name) || metadata.many?
+              if relation_exists?(name) || metadata.many? ||
+                (object.blank? && send(name))
                 set_relation(name, send(name).substitute(object.substitutable))
               else
                 build(name, object.substitutable, metadata)

lib/mongoid/relations/binding.rb

@@ -17,10 +17,10 @@ class Binding
       #
       # @since 2.1.0
       def binding
-        Threaded.binding = true
+        Threaded.begin_bind
         yield
       ensure
-        Threaded.binding = false
+        Threaded.exit_bind
       end
 
       # Is the current thread in binding mode?

lib/mongoid/threaded.rb

@@ -6,6 +6,18 @@ module Mongoid #:nodoc:
   module Threaded
     extend self
 
+    # Begins a binding block.
+    #
+    # @example Begin the bind.
+    #   Threaded.begin_bind
+    #
+    # @return [ true ] Always true.
+    #
+    # @since 2.1.9
+    def begin_bind
+      bind_stack.push(true)
+    end
+
     # Begins a building block.
     #
     # @example Begin the build.
@@ -18,30 +30,28 @@ def begin_build
       build_stack.push(true)
     end
 
-    # Is the current thread in binding mode?
+    # Begin validating a document on the current thread.
     #
-    # @example Is the thread in binding mode?
-    #   Threaded.binding?
+    # @example Begin validation.
+    #   Threaded.begin_validate(doc)
     #
-    # @return [ true, false ] If the thread is in binding mode?
+    # @param [ Document ] document The document to validate.
     #
-    # @since 2.1.0
-    def binding?
-      Thread.current[:"[mongoid]:binding-mode"] ||= false
+    # @since 2.1.9
+    def begin_validate(document)
+      validations_for(document.class).push(document.id)
     end
 
-    # Set the binding mode for the current thread.
-    #
-    # @example Set the binding mode.
-    #   Threaded.binding = true
+    # Is the current thread in binding mode?
     #
-    # @param [ true, false ] mode The current binding mode.
+    # @example Is the thread in binding mode?
+    #   Threaded.binding?
     #
-    # @return [ true, false ] The current binding mode.
+    # @return [ true, false ] If the thread is in binding mode?
     #
     # @since 2.1.0
-    def binding=(mode)
-      Thread.current[:"[mongoid]:binding-mode"] = mode
+    def binding?
+      !bind_stack.empty?
     end
 
     # Is the current thread in building mode?
@@ -56,6 +66,19 @@ def building?
       !build_stack.empty?
     end
 
+    # Get the bind stack for the current thread. Is simply an array of calls
+    # to Mongoid's binding method.
+    #
+    # @example Get the bind stack.
+    #   Threaded.bind_stack
+    #
+    # @return [ Array ] The array of bind calls.
+    #
+    # @since 2.1.9
+    def bind_stack
+      Thread.current[:"[mongoid]:bind-stack"] ||= []
+    end
+
     # Get the build stack for the current thread. Is simply an array of calls
     # to Mongoid's building method.
     #
@@ -81,6 +104,18 @@ def clear_safety_options!
       Thread.current[:"[mongoid]:safety-options"] = nil
     end
 
+    # Exit the binding block.
+    #
+    # @example Exit the binding block.
+    #   Threaded.exit_bind
+    #
+    # @return [ true ] The last element in the stack.
+    #
+    # @since 2.1.9
+    def exit_bind
+      bind_stack.pop
+    end
+
     # Exit the building block.
     #
     # @example Exit the building block.
@@ -93,6 +128,18 @@ def exit_build
       build_stack.pop
     end
 
+    # Exit validating a document on the current thread.
+    #
+    # @example Exit validation.
+    #   Threaded.exit_validate(doc)
+    #
+    # @param [ Document ] document The document to validate.
+    #
+    # @since 2.1.9
+    def exit_validate(document)
+      validations_for(document.class).delete_one(document.id)
+    end
+
     # Get the identity map off the current thread.
     #
     # @example Get the identity map.
@@ -194,5 +241,45 @@ def update_consumer(klass)
     def set_update_consumer(klass, consumer)
       Thread.current[:"[mongoid][#{klass}]:update-consumer"] = consumer
     end
+
+    # Is the document validated on the current thread?
+    #
+    # @example Is the document validated?
+    #   Threaded.validated?(doc)
+    #
+    # @param [ Document ] document The document to check.
+    #
+    # @return [ true, false ] If the document is validated.
+    #
+    # @since 2.1.9
+    def validated?(document)
+      validations_for(document.class).include?(document.id)
+    end
+
+    # Get all validations on the current thread.
+    #
+    # @example Get all validations.
+    #   Threaded.validations
+    #
+    # @return [ Hash ] The current validations.
+    #
+    # @since 2.1.9
+    def validations
+      Thread.current[:"[mongoid]:validations"] ||= {}
+    end
+
+    # Get all validations on the current thread for the class.
+    #
+    # @example Get all validations.
+    #   Threaded.validations_for(Person)
+    #
+    # @param [ Class ] The class to check.
+    #
+    # @return [ Array ] The current validations.
+    #
+    # @since 2.1.9
+    def validations_for(klass)
+      validations[klass] ||= []
+    end
   end
 end

lib/mongoid/validations.rb

@@ -10,7 +10,25 @@ module Validations
     extend ActiveSupport::Concern
     include ActiveModel::Validations
 
-    attr_accessor :validated
+    # Begin the associated validation.
+    #
+    # @example Begin validation.
+    #   document.begin_validate
+    #
+    # @since 2.1.9
+    def begin_validate
+      Threaded.begin_validate(self)
+    end
+
+    # Exit the associated validation.
+    #
+    # @example Exit validation.
+    #   document.exit_validate
+    #
+    # @since 2.1.9
+    def exit_validate
+      Threaded.exit_validate(self)
+    end
 
     # Overrides the default ActiveModel behaviour since we need to handle
     # validations of relations slightly different than just calling the
@@ -59,7 +77,7 @@ def valid?(context = nil)
     #
     # @since 2.0.0.rc.2
     def validated?
-      !!@validated
+      Threaded.validated?(self)
     end
 
     module ClassMethods #:nodoc:

lib/mongoid/validations/associated.rb

@@ -27,15 +27,18 @@ class AssociatedValidator < ActiveModel::EachValidator
       # @param [ Symbol ] attribute The relation to validate.
       # @param [ Object ] value The value of the relation.
       def validate_each(document, attribute, value)
-        document.validated = true
-        valid = Array.wrap(value).collect do |doc|
-          if doc.nil?
-            true
-          else
-            doc.validated? ? true : doc.valid?
-          end
-        end.all?
-        document.validated = false
+        begin
+          document.begin_validate
+          valid = Array.wrap(value).collect do |doc|
+            if doc.nil?
+              true
+            else
+              doc.validated? ? true : doc.valid?
+            end
+          end.all?
+        ensure
+          document.exit_validate
+        end
         return if valid
         document.errors.add(attribute, :invalid, options.merge(:value => value))
       end