Add ActiveStorage::Service#open

activestorage/app/models/active_storage/blob.rb

@@ -193,17 +193,18 @@ def download(&block)
   #
   # The tempfile's name is prefixed with +ActiveStorage-+ and the blob's ID. Its extension matches that of the blob.
   #
-  # By default, the tempfile is created in <tt>Dir.tmpdir</tt>. Pass +tempdir:+ to create it in a different directory:
+  # By default, the tempfile is created in <tt>Dir.tmpdir</tt>. Pass +tmpdir:+ to create it in a different directory:
   #
-  #   blob.open(tempdir: "/path/to/tmp") do |file|
+  #   blob.open(tmpdir: "/path/to/tmp") do |file|
   #     # ...
   #   end
   #
   # The tempfile is automatically closed and unlinked after the given block is executed.
   #
   # Raises ActiveStorage::IntegrityError if the downloaded data does not match the blob's checksum.
-  def open(tempdir: nil, &block)
-    ActiveStorage::Downloader.new(self, tempdir: tempdir).download_blob_to_tempfile(&block)
+  def open(tmpdir: nil, &block)
+    service.open key, checksum: checksum,
+      name: [ "ActiveStorage-#{id}-", filename.extension_with_delimiter ], tmpdir: tmpdir, &block
   end
 
 

activestorage/lib/active_storage/analyzer.rb

@@ -24,14 +24,14 @@ def metadata
     private
       # Downloads the blob to a tempfile on disk. Yields the tempfile.
       def download_blob_to_tempfile(&block) #:doc:
-        blob.open tempdir: tempdir, &block
+        blob.open tmpdir: tmpdir, &block
       end
 
       def logger #:doc:
         ActiveStorage.logger
       end
 
-      def tempdir #:doc:
+      def tmpdir #:doc:
         Dir.tmpdir
       end
   end

activestorage/lib/active_storage/downloader.rb

@@ -2,24 +2,23 @@
 
 module ActiveStorage
   class Downloader #:nodoc:
-    def initialize(blob, tempdir: nil)
-      @blob    = blob
-      @tempdir = tempdir
+    attr_reader :service
+
+    def initialize(service)
+      @service = service
     end
 
-    def download_blob_to_tempfile
-      open_tempfile do |file|
-        download_blob_to file
-        verify_integrity_of file
+    def open(key, checksum:, name: "ActiveStorage-", tmpdir: nil)
+      open_tempfile(name, tmpdir) do |file|
+        download key, file
+        verify_integrity_of file, checksum: checksum
         yield file
       end
     end
 
     private
-      attr_reader :blob, :tempdir
-
-      def open_tempfile
-        file = Tempfile.open([ "ActiveStorage-#{blob.id}-", blob.filename.extension_with_delimiter ], tempdir)
+      def open_tempfile(name, tmpdir = nil)
+        file = Tempfile.open(name, tmpdir)
 
         begin
           yield file
@@ -28,15 +27,15 @@ def open_tempfile
         end
       end
 
-      def download_blob_to(file)
+      def download(key, file)
         file.binmode
-        blob.download { |chunk| file.write(chunk) }
+        service.download(key) { |chunk| file.write(chunk) }
         file.flush
         file.rewind
       end
 
-      def verify_integrity_of(file)
-        unless Digest::MD5.file(file).base64digest == blob.checksum
+      def verify_integrity_of(file, checksum:)
+        unless Digest::MD5.file(file).base64digest == checksum
           raise ActiveStorage::IntegrityError
         end
       end

activestorage/lib/active_storage/previewer.rb

@@ -26,7 +26,7 @@ def preview
     private
       # Downloads the blob to a tempfile on disk. Yields the tempfile.
       def download_blob_to_tempfile(&block) #:doc:
-        blob.open tempdir: tempdir, &block
+        blob.open tmpdir: tmpdir, &block
       end
 
       # Executes a system command, capturing its binary output in a tempfile. Yields the tempfile.
@@ -42,7 +42,7 @@ def download_blob_to_tempfile(&block) #:doc:
       #     end
       #   end
       #
-      # The output tempfile is opened in the directory returned by #tempdir.
+      # The output tempfile is opened in the directory returned by #tmpdir.
       def draw(*argv) #:doc:
         open_tempfile do |file|
           instrument :preview, key: blob.key do
@@ -54,7 +54,7 @@ def draw(*argv) #:doc:
       end
 
       def open_tempfile
-        tempfile = Tempfile.open("ActiveStorage-", tempdir)
+        tempfile = Tempfile.open("ActiveStorage-", tmpdir)
 
         begin
           yield tempfile
@@ -77,7 +77,7 @@ def logger #:doc:
         ActiveStorage.logger
       end
 
-      def tempdir #:doc:
+      def tmpdir #:doc:
         Dir.tmpdir
       end
   end

activestorage/lib/active_storage/service.rb

@@ -82,6 +82,10 @@ def download_chunk(key, range)
       raise NotImplementedError
     end
 
+    def open(*args, &block)
+      ActiveStorage::Downloader.new(self).open(*args, &block)
+    end
+
     # Delete the file at the +key+.
     def delete(key)
       raise NotImplementedError

activestorage/test/models/blob_test.rb

@@ -104,14 +104,12 @@ class ActiveStorage::BlobTest < ActiveSupport::TestCase
     end
   end
 
-  test "open in a custom tempdir" do
-    tempdir = Dir.mktmpdir
-
-    create_file_blob(filename: "racecar.jpg").open(tempdir: tempdir) do |file|
+  test "open in a custom tmpdir" do
+    create_file_blob(filename: "racecar.jpg").open(tmpdir: tmpdir = Dir.mktmpdir) do |file|
       assert file.binmode?
       assert_equal 0, file.pos
       assert_match(/\.jpg\z/, file.path)
-      assert file.path.starts_with?(tempdir)
+      assert file.path.starts_with?(tmpdir)
       assert_equal file_fixture("racecar.jpg").binread, file.read, "Expected downloaded file to match fixture file"
     end
   end