Make Attacher#read method public

We changed Attacher#reload to reset dirty tracking in addition to
loading attachment data. However, it's nice to also allow just loading
attachment data and keeping dirty tracking as is. That's what
Attacher#read method does.

This is consistent with Attacher#write which is public as well.

CHANGELOG.md

@@ -1,5 +1,7 @@
 ## HEAD
 
+* `entity` – Make `Attacher#read` method public (@janko)
+
 * `entity` – Reset attachment dirty tracking in `Attacher#reload` (@janko)
 
 * `activerecord` – Don't load the attacher on `ActiveRecord::Base#reload` if it hasn't yet been initialized (@janko)

doc/plugins/entity.md

@@ -206,6 +206,9 @@ attacher.reload
 attacher.file #=> #<ImageUploader::UploadedFile>
 ```
 
+If you want to reload attachment data while retaining dirty tracking state, use
+`Attacher#read` instead.
+
 ### Column values
 
 The `Attacher#column_values` method returns a hash with the entity attribute as

lib/shrine/plugins/entity.rb

@@ -116,6 +116,11 @@ def reload
           self
         end
 
+        # Loads attachment from the entity attribute.
+        def read
+          load_column(read_attribute)
+        end
+
         # Returns a hash with entity attribute name and column data.
         #
         #     attacher.column_values
@@ -135,11 +140,6 @@ def attribute
 
         private
 
-        # Loads attachment from the entity attribute.
-        def read
-          load_column(read_attribute)
-        end
-
         # Reads value from the entity attribute.
         def read_attribute
           record.public_send(attribute)

test/plugin/entity_test.rb

@@ -226,6 +226,16 @@
       end
     end
 
+    describe "#read" do
+      it "loads entity file data" do
+        @attacher.load_entity(@entity_class.new, :file)
+        @attacher.attach(fakeio)
+        @attacher.read
+
+        assert_nil @attacher.file
+      end
+    end
+
     describe "#column_values" do
       it "returns column values with an attached file" do
         @attacher.load_entity(@entity_class.new, :file)