1 files changed, 74 insertions, 0 deletions
diff --git a/activemodel/CHANGELOG.md b/activemodel/CHANGELOG.md
index b86e988841..4c78fc91a5 100644
--- a/activemodel/CHANGELOG.md
+++ b/activemodel/CHANGELOG.md
@@ -1 +1,75 @@
+*   Change the default error message from `can't be blank` to `must exist` for
+    the presence validator of the `:required` option on `belongs_to`/`has_one` associations.
+
+    *Henrik Nygren*
+
+*   Assigning an unknown attribute key to an `ActiveModel` instance during initialization
+    will now raise `ActiveModel::AttributeAssignment::UnknownAttributeError` instead of
+    `NoMethodError`
+
+    Example:
+
+        User.new(foo: 'some value')
+        # => ActiveModel::AttributeAssignment::UnknownAttributeError: unknown attribute 'foo' for User.
+
+    *Eugene Gilburg*
+
+*   Extracted `ActiveRecord::AttributeAssignment` to `ActiveModel::AttributeAssignment`
+    allowing to use it for any object as an includable module.
+
+    Example:
+
+        class Cat
+          include ActiveModel::AttributeAssignment
+          attr_accessor :name, :status
+        end
+
+        cat = Cat.new
+        cat.assign_attributes(name: "Gorby", status: "yawning")
+        cat.name # => 'Gorby'
+        cat.status => 'yawning'
+        cat.assign_attributes(status: "sleeping")
+        cat.name # => 'Gorby'
+        cat.status => 'sleeping'
+
+    *Bogdan Gusiev*
+
+*   Add `ActiveModel::Errors#details`
+
+    To be able to return type of used validator, one can now call `details`
+    on errors instance.
+
+    Example:
+
+        class User < ActiveRecord::Base
+          validates :name, presence: true
+        end
+
+        user = User.new; user.valid?; user.errors.details
+        => {name: [{error: :blank}]}
+
+    *Wojciech Wnętrzak*
+
+*   Change validates_acceptance_of to accept true by default.
+
+    The default for validates_acceptance_of is now "1" and true.
+    In the past, only "1" was the default and you were required to add
+    accept: true.
+
+*   Remove deprecated `ActiveModel::Dirty#reset_#{attribute}` and
+    `ActiveModel::Dirty#reset_changes`.
+
+    *Rafael Mendonça França*
+
+*   Change the way in which callback chains can be halted.
+
+    The preferred method to halt a callback chain from now on is to explicitly
+    `throw(:abort)`.
+    In the past, returning `false` in an ActiveModel or ActiveModel::Validations
+    `before_` callback had the side effect of halting the callback chain.
+    This is not recommended anymore and, depending on the value of the
+    `config.active_support.halt_callback_chains_on_return_false` option, will
+    either not work at all or display a deprecation warning.
+
+
 Please check [4-2-stable](https://github.com/rails/rails/blob/4-2-stable/activemodel/CHANGELOG.md) for previous changes.