Question

I’m running a script that updates a metadata field on some of my S3 objects after they have already been uploaded to the S3 bucket. On initialization, I am setting the content-type by checking the file name.

def save_to_amazon(file, s3_object, file_name, meta_path)
  puts "uploaded #{file} to Amazon S3"
  content_type = set_content_type(file_name)
    s3_object.write(file.get_input_stream.read, :metadata => { :folders => meta_path}, :content_type => content_type)
end

At this point, the S3 content-type works fine for these objects. The problem arises when I update the metadata later on. I run something like this:

s3_object.metadata['folders'] = "some string"

At this point, I get an empty string returned when I run s3_objects.content_type after updating the metadata.

s3_object.content_type = is not available.

As far as I can tell from reading the Rdoc there isn’t a way to assign content-type after uploading the S3 file. I have tried using the metadata method like

s3.object.metadata['content_type'] = "some string"
s3.object.metadata['content-type'] = "some string"

Both of these appear to assign a new custom metadata attribute instead of updating the object’s mime type.

Is there a way to set this, or do I need to completely re-upload the file again?

Answer 1

To elaborate on tkotisis reponse, here is what I did to update the content-type using copy_to. You can use s3object.head[:metadata] to pull out the existing metadata to copy it over as referenced here.

amazon_bucket.objects.each do |ob|
    metadata = ob.head[:metadata]
    content_type = "foo/bar"
    ob.copy_to(ob.key, :metadata => metadata, :content_type => content_type)
end

EDIT

amazon_bucket.objects.each do |ob|
    metadata = ob.metadata
    content_type = "foo/bar"
    ob.copy_to(ob.key, :metadata{:foo => metadata[:foo]}, :content_type => content_type)
end