diff --git a/app/models/comment.rb b/app/models/comment.rb
index 112aa4fe5..cc0113ea2 100644
--- a/app/models/comment.rb
+++ b/app/models/comment.rb
@@ -7,6 +7,7 @@ class Comment < ActiveRecord::Base
   include Diaspora::Federated::Base
 
   include Diaspora::Guid
+  include Diaspora::Fields::Author
   include Diaspora::Relayable
 
   include Diaspora::Taggable
@@ -19,10 +20,8 @@ class Comment < ActiveRecord::Base
   belongs_to :commentable, :touch => true, :polymorphic => true
   alias_attribute :post, :commentable
   alias_attribute :parent, :commentable
-  belongs_to :author, class_name: "Person"
 
   delegate :name, to: :author, prefix: true
-  delegate :diaspora_handle, to: :author
   delegate :comment_email_subject, to: :parent
   delegate :author_name, to: :parent, prefix: true
 
@@ -48,10 +47,6 @@ class Comment < ActiveRecord::Base
     participation.unparticipate! if participation.present?
   end
 
-  def diaspora_handle=(nh)
-    self.author = Person.find_or_fetch_by_identifier(nh)
-  end
-
   def message
     @message ||= Diaspora::MessageRenderer.new text
   end
diff --git a/app/models/conversation.rb b/app/models/conversation.rb
index 873cb7f58..e22aab040 100644
--- a/app/models/conversation.rb
+++ b/app/models/conversation.rb
@@ -1,14 +1,12 @@
 class Conversation < ActiveRecord::Base
   include Diaspora::Federated::Base
   include Diaspora::Guid
+  include Diaspora::Fields::Author
 
   has_many :conversation_visibilities, dependent: :destroy
   has_many :participants, class_name: "Person", through: :conversation_visibilities, source: :person
   has_many :messages, -> { order("created_at ASC") }, inverse_of: :conversation
 
-  belongs_to :author, class_name: "Person"
-  delegate :diaspora_handle, to: :author
-
   validate :max_participants
   validate :local_recipients
 
@@ -33,10 +31,6 @@ class Conversation < ActiveRecord::Base
     self.participants - [self.author]
   end
 
-  def diaspora_handle=(nh)
-    self.author = Person.find_or_fetch_by_identifier(nh)
-  end
-
   def first_unread_message(user)
     if visibility = self.conversation_visibilities.where(:person_id => user.person.id).where('unread > 0').first
       self.messages.to_a[-visibility.unread]
diff --git a/app/models/message.rb b/app/models/message.rb
index 8138b433e..c4e5ccf0b 100644
--- a/app/models/message.rb
+++ b/app/models/message.rb
@@ -1,25 +1,19 @@
 class Message < ActiveRecord::Base
   include Diaspora::Federated::Base
   include Diaspora::Guid
+  include Diaspora::Fields::Author
 
-  belongs_to :author, class_name: "Person"
   belongs_to :conversation, touch: true
 
-  delegate :diaspora_handle, to: :author
   delegate :name, to: :author, prefix: true
 
   # TODO: can be removed when messages are not relayed anymore
   alias_attribute :parent, :conversation
 
   validates :conversation, presence: true
-  validates :author, presence: true
   validates :text, presence: true
   validate :participant_of_parent_conversation
 
-  def diaspora_handle=(nh)
-    self.author = Person.find_or_fetch_by_identifier(nh)
-  end
-
   def conversation_guid=(guid)
     self.conversation_id = Conversation.where(guid: guid).ids.first
   end
diff --git a/app/models/poll_participation.rb b/app/models/poll_participation.rb
index a81daa5e9..7a2c0e360 100644
--- a/app/models/poll_participation.rb
+++ b/app/models/poll_participation.rb
@@ -1,14 +1,11 @@
 class PollParticipation < ActiveRecord::Base
   include Diaspora::Federated::Base
-
   include Diaspora::Guid
+  include Diaspora::Fields::Author
   include Diaspora::Relayable
 
   belongs_to :poll
   belongs_to :poll_answer, counter_cache: :vote_count
-  belongs_to :author, class_name: "Person"
-
-  delegate :diaspora_handle, to: :author
 
   alias_attribute :parent, :poll
 
@@ -19,10 +16,6 @@ class PollParticipation < ActiveRecord::Base
     self.poll_answer_id = PollAnswer.where(guid: new_poll_answer_guid).ids.first
   end
 
-  def diaspora_handle=(nh)
-    self.author = Person.find_or_fetch_by_identifier(nh)
-  end
-
   def not_already_participated
     return if poll.nil?
 
diff --git a/app/models/post.rb b/app/models/post.rb
index 6eda1fbe0..fe4ddf6cb 100644
--- a/app/models/post.rb
+++ b/app/models/post.rb
@@ -30,8 +30,6 @@ class Post < ActiveRecord::Base
 
   validates_uniqueness_of :id
 
-  validates :author, presence: true
-
   after_create do
     self.touch(:interacted_at)
   end
diff --git a/lib/diaspora/fields/author.rb b/lib/diaspora/fields/author.rb
new file mode 100644
index 000000000..eaabbf27f
--- /dev/null
+++ b/lib/diaspora/fields/author.rb
@@ -0,0 +1,19 @@
+module Diaspora
+  module Fields
+    module Author
+      def self.included(model)
+        model.class_eval do
+          belongs_to :author, class_name: "Person"
+
+          delegate :diaspora_handle, to: :author
+
+          validates :author, presence: true
+        end
+      end
+
+      def diaspora_handle=(nh)
+        self.author = Person.find_or_fetch_by_identifier(nh)
+      end
+    end
+  end
+end
diff --git a/lib/diaspora/relayable.rb b/lib/diaspora/relayable.rb
index 49fe2be94..247fd827b 100644
--- a/lib/diaspora/relayable.rb
+++ b/lib/diaspora/relayable.rb
@@ -7,7 +7,6 @@ module Diaspora
     def self.included(model)
       model.class_eval do
         validates_associated :parent
-        validates :author, :presence => true
         validate :author_is_not_ignored
 
         delegate :public?, to: :parent
diff --git a/lib/diaspora/shareable.rb b/lib/diaspora/shareable.rb
index 84193951a..5adee7053 100644
--- a/lib/diaspora/shareable.rb
+++ b/lib/diaspora/shareable.rb
@@ -9,15 +9,13 @@ module Diaspora
     def self.included(model)
       model.instance_eval do
         include Diaspora::Guid
+        include Diaspora::Fields::Author
 
         has_many :aspect_visibilities, as: :shareable, validate: false, dependent: :delete_all
         has_many :aspects, through: :aspect_visibilities
 
         has_many :share_visibilities, as: :shareable, dependent: :delete_all
 
-        belongs_to :author, class_name: "Person"
-
-        delegate :diaspora_handle, to: :author
         delegate :id, :name, :first_name, to: :author, prefix: true
 
         # scopes
@@ -42,10 +40,6 @@ module Diaspora
       ShareVisibility.batch_import(recipient_user_ids, self)
     end
 
-    def diaspora_handle=(author_handle)
-      self.author = Person.where(diaspora_handle: author_handle).first
-    end
-
     # The list of people that should receive this Shareable.
     #
     # @return [Array<Person>] The list of subscribers to this shareable
diff --git a/lib/federated/relayable.rb b/lib/federated/relayable.rb
index 72c82043f..e3973185e 100644
--- a/lib/federated/relayable.rb
+++ b/lib/federated/relayable.rb
@@ -4,21 +4,15 @@ module Federated
 
     include Diaspora::Federated::Base
     include Diaspora::Guid
+    include Diaspora::Fields::Author
 
     include Diaspora::Relayable
 
     belongs_to :target, polymorphic: true
-    belongs_to :author, class_name: "Person"
-
-    delegate :diaspora_handle, to: :author
 
     alias_attribute :parent, :target
 
     validates :target_id, uniqueness: {scope: %i(target_type author_id)}
     validates :target, presence: true # should be in relayable (pending on fixing Message)
-
-    def diaspora_handle=(nh)
-      self.author = Person.find_or_fetch_by_identifier(nh)
-    end
   end
 end