The ActiveRecord "_changed?" method returns false after assigning a file with the same file name but different content

[bli]

With an existing active record with an existing file, if you assign a new version of the file (with the same file name but different content), the "_changed?" method returns false instead true.

To demonstrate this, we can add a test in activerecord_spec.rb, just after the test "should mark image as changed when saving a new image".

      it "should mark image as changed when saving a new image with same file name" do
        @event.image = stub_file("test.jpeg")
        @event.save
        @event.image = stub_file_alt("test.jpeg")
        expect(@event.image_changed?).to be_truthy
        @event.save
        expect(@event.reload.image.read).to eq "this is new stuff\n"
      end

Here the stub_file_alt is similar to stub_file. The difference is that it gets the file from another directory (so that we can have a different fixture with the same file name).

      def stub_file_alt(filename, mime_type=nil, fake_name=nil)
        f = File.open(file_path("alternatives", filename))
        allow(f).to receive(:content_type) { mime_type } if mime_type
        f
      end

The test failed the first expect. However the second expect would pass should we comment out the first one.

Note that this is the same scenario mentioned in #2712. But the issue here is the "_changed?", ".changes" methods do not reflect the fact that the content of the file has been changed.

This seems to be an issue since version 3.0.0.rc.

[IsaacConDosA]

The fix didn't work for me :(. In 1.x and 2.x it works

My code is

book.author.remote_image_url = new_uri
book.author.changed? # false