4 files changed, 85 insertions, 7 deletions
diff --git a/lib/active_vault/attachment.rb b/lib/active_vault/attachment.rb
new file mode 100644
index 0000000000..eb108e9cbb
--- /dev/null
+++ b/lib/active_vault/attachment.rb
@@ -0,0 +1,27 @@
+require "active_vault/blob"
+require "global_id"
+require "active_support/core_ext/module/delegation"
+
+# Schema: id, record_gid, blob_id, created_at
+class ActiveVault::Attachment < ActiveRecord::Base
+  self.table_name = "active_vault_attachments"
+
+  belongs_to :blob, class_name: "ActiveVault::Blob"
+
+  delegate_missing_to :blob
+
+  def record
+    @record ||= GlobalID::Locator.locate(record_gid)
+  end
+
+  def record=(record)
+    @record = record
+    self.record_gid = record&.to_gid
+  end
+
+  def purge
+    blob.purge
+    destroy
+    record.public_send "#{name}=", nil
+  end
+end
diff --git a/lib/active_vault/attachments.rb b/lib/active_vault/attachments.rb
new file mode 100644
index 0000000000..c66c142650
--- /dev/null
+++ b/lib/active_vault/attachments.rb
@@ -0,0 +1,30 @@
+require "active_vault/attachment"
+require "action_dispatch/http/upload"
+
+module ActiveVault::Attachments
+  def has_file(name)
+    define_method(name) do
+      (@active_vault_attachments ||= {})[name] ||=
+        ActiveVault::Attachment.find_by(record_gid: to_gid.to_s, name: name)&.tap { |a| a.record = self }
+    end
+
+    define_method(:"#{name}=") do |attachable|
+      case attachable
+      when ActiveVault::Blob
+        blob = attachable
+      when ActionDispatch::Http::UploadedFile
+        blob = ActiveVault::Blob.create_after_upload! \
+          io: attachable.open,
+          filename: attachable.original_filename,
+          content_type: attachable.content_type
+      when Hash
+        blob = ActiveVault::Blob.create_after_upload!(attachable)
+      when NilClass
+        blob = nil
+      end
+
+      (@active_vault_attachments ||= {})[name] = blob ?
+        ActiveVault::Attachment.create!(record_gid: to_gid.to_s, name: name, blob: blob)&.tap { |a| a.record = self } : nil
+    end
+  end
+end
diff --git a/lib/active_vault/migration.rb b/lib/active_vault/migration.rb
index b3c66428ce..985d26d1b9 100644
--- a/lib/active_vault/migration.rb
+++ b/lib/active_vault/migration.rb
@@ -1,15 +1,28 @@
-class ActiveVault::CreateBlobs < ActiveRecord::Migration[5.1]
+class ActiveVault::CreateTables < ActiveRecord::Migration[5.1]
   def change
-      t.string :key
-      t.string :filename
-      t.string :content_type
-      t.text :metadata
     create_table :active_vault_blobs do |t|
+      t.string  :key
+      t.string  :filename
+      t.string  :content_type
+      t.text    :metadata
       t.integer :byte_size
-      t.string :checksum
-      t.time :created_at
+      t.string  :checksum
+      t.time    :created_at
 
       t.index [ :key ], unique: true
     end
+
+    create_table :active_vault_attachments do |t|
+      t.string  :name
+      t.string  :record_gid
+      t.integer :blob_id
+
+      t.time :created_at
+
+      t.index :record_gid
+      t.index :blob_id
+      t.index [ :record_gid, :name ]
+      t.index [ :record_gid, :blob_id ], unique: true
+    end
   end
 end
diff --git a/lib/active_vault/railtie.rb b/lib/active_vault/railtie.rb
index c254f4c77c..f1c5740aa5 100644
--- a/lib/active_vault/railtie.rb
+++ b/lib/active_vault/railtie.rb
@@ -15,5 +15,13 @@ module ActiveVault
         end
       end
     end
+
+    initializer "action_file.attachments" do
+      require "active_vault/attachments"
+
+      ActiveSupport.on_load(:active_record) do
+        extend ActiveVault::Attachments
+      end
+    end
   end
 end