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module AWS
module S3
# S3Objects represent the data you store on S3. They have a key (their name) and a value (their data). All objects belong to a
# bucket.
#
# You can store an object on S3 by specifying a key, its data and the name of the bucket you want to put it in:
#
# S3Object.store('me.jpg', open('headshot.jpg'), 'photos')
#
# The content type of the object will be inferred by its extension. If the appropriate content type can not be inferred, S3 defaults
# to <tt>binary/octet-stream</tt>.
#
# If you want to override this, you can explicitly indicate what content type the object should have with the <tt>:content_type</tt> option:
#
# file = 'black-flowers.m4a'
# S3Object.store(
# file,
# open(file),
# 'jukebox',
# :content_type => 'audio/mp4a-latm'
# )
#
# You can read more about storing files on S3 in the documentation for S3Object.store.
#
# If you just want to fetch an object you've stored on S3, you just specify its name and its bucket:
#
# picture = S3Object.find 'headshot.jpg', 'photos'
#
# N.B. The actual data for the file is not downloaded in both the example where the file appeared in the bucket and when fetched directly.
# You get the data for the file like this:
#
# picture.value
#
# You can fetch just the object's data directly:
#
# S3Object.value 'headshot.jpg', 'photos'
#
# Or stream it by passing a block to <tt>stream</tt>:
#
# open('song.mp3', 'w') do |file|
# S3Object.stream('song.mp3', 'jukebox') do |chunk|
# file.write chunk
# end
# end
#
# The data of the file, once download, is cached, so subsequent calls to <tt>value</tt> won't redownload the file unless you
# tell the object to reload its <tt>value</tt>:
#
# # Redownloads the file's data
# song.value(:reload)
#
# Other functionality includes:
#
# # Check if an object exists?
# S3Object.exists? 'headshot.jpg', 'photos'
#
# # Copying an object
# S3Object.copy 'headshot.jpg', 'headshot2.jpg', 'photos'
#
# # Renaming an object
# S3Object.rename 'headshot.jpg', 'portrait.jpg', 'photos'
#
# # Deleting an object
# S3Object.delete 'headshot.jpg', 'photos'
#
# ==== More about objects and their metadata
#
# You can find out the content type of your object with the <tt>content_type</tt> method:
#
# song.content_type
# # => "audio/mpeg"
#
# You can change the content type as well if you like:
#
# song.content_type = 'application/pdf'
# song.store
#
# (Keep in mind that due to limitiations in S3's exposed API, the only way to change things like the content_type
# is to PUT the object onto S3 again. In the case of large files, this will result in fully re-uploading the file.)
#
# A bevie of information about an object can be had using the <tt>about</tt> method:
#
# pp song.about
# {"last-modified" => "Sat, 28 Oct 2006 21:29:26 GMT",
# "content-type" => "binary/octet-stream",
# "etag" => "\"dc629038ffc674bee6f62eb64ff3a\"",
# "date" => "Sat, 28 Oct 2006 21:30:41 GMT",
# "x-amz-request-id" => "B7BC68F55495B1C8",
# "server" => "AmazonS3",
# "content-length" => "3418766"}
#
# You can get and set metadata for an object:
#
# song.metadata
# # => {}
# song.metadata[:album] = "A River Ain't Too Much To Love"
# # => "A River Ain't Too Much To Love"
# song.metadata[:released] = 2005
# pp song.metadata
# {"x-amz-meta-released" => 2005,
# "x-amz-meta-album" => "A River Ain't Too Much To Love"}
# song.store
#
# That metadata will be saved in S3 and is hence forth available from that object:
#
# song = S3Object.find('black-flowers.mp3', 'jukebox')
# pp song.metadata
# {"x-amz-meta-released" => "2005",
# "x-amz-meta-album" => "A River Ain't Too Much To Love"}
# song.metadata[:released]
# # => "2005"
# song.metadata[:released] = 2006
# pp song.metadata
# {"x-amz-meta-released" => 2006,
# "x-amz-meta-album" => "A River Ain't Too Much To Love"}
class S3Object < Base
class << self
# Returns the value of the object with <tt>key</tt> in the specified bucket.
#
# === Conditional GET options
#
# * <tt>:if_modified_since</tt> - Return the object only if it has been modified since the specified time,
# otherwise return a 304 (not modified).
# * <tt>:if_unmodified_since</tt> - Return the object only if it has not been modified since the specified time,
# otherwise raise PreconditionFailed.
# * <tt>:if_match</tt> - Return the object only if its entity tag (ETag) is the same as the one specified,
# otherwise raise PreconditionFailed.
# * <tt>:if_none_match</tt> - Return the object only if its entity tag (ETag) is different from the one specified,
# otherwise return a 304 (not modified).
#
# === Other options
# * <tt>:range</tt> - Return only the bytes of the object in the specified range.
def value(key, bucket = nil, options = {}, &block)
Value.new(get(path!(bucket, key, options), options, &block))
end
def stream(key, bucket = nil, options = {}, &block)
value(key, bucket, options) do |response|
response.read_body(&block)
end
end
# Returns the object whose key is <tt>name</tt> in the specified bucket. If the specified key does not
# exist, a NoSuchKey exception will be raised.
def find(key, bucket = nil)
# N.B. This is arguably a hack. From what the current S3 API exposes, when you retrieve a bucket, it
# provides a listing of all the files in that bucket (assuming you haven't limited the scope of what it returns).
# Each file in the listing contains information about that file. It is from this information that an S3Object is built.
#
# If you know the specific file that you want, S3 allows you to make a get request for that specific file and it returns
# the value of that file in its response body. This response body is used to build an S3Object::Value object.
# If you want information about that file, you can make a head request and the headers of the response will contain
# information about that file. There is no way, though, to say, give me the representation of just this given file the same
# way that it would appear in a bucket listing.
#
# When fetching a bucket, you can provide options which narrow the scope of what files should be returned in that listing.
# Of those options, one is <tt>marker</tt> which is a string and instructs the bucket to return only object's who's key comes after
# the specified marker according to alphabetic order. Another option is <tt>max-keys</tt> which defaults to 1000 but allows you
# to dictate how many objects should be returned in the listing. With a combination of <tt>marker</tt> and <tt>max-keys</tt> you can
# *almost* specify exactly which file you'd like it to return, but <tt>marker</tt> is not inclusive. In other words, if there is a bucket
# which contains three objects who's keys are respectively 'a', 'b' and 'c', then fetching a bucket listing with marker set to 'b' will only
# return 'c', not 'b'.
#
# Given all that, my hack to fetch a bucket with only one specific file, is to set the marker to the result of calling String#previous on
# the desired object's key, which functionally makes the key ordered one degree higher than the desired object key according to
# alphabetic ordering. This is a hack, but it should work around 99% of the time. I can't think of a scenario where it would return
# something incorrect.
# We need to ensure the key doesn't have extended characters but not uri escape it before doing the lookup and comparing since if the object exists,
# the key on S3 will have been normalized
key = key.remove_extended unless key.valid_utf8?
bucket = Bucket.find(bucket_name(bucket), :marker => key.previous, :max_keys => 1)
# If our heuristic failed, trigger a NoSuchKey exception
if (object = bucket.objects.first) && object.key == key
object
else
raise NoSuchKey.new("No such key `#{key}'", bucket)
end
end
# Makes a copy of the object with <tt>key</tt> to <tt>copy_key</tt>, preserving the ACL of the existing object if the <tt>:copy_acl</tt> option is true (default false).
def copy(key, copy_key, bucket = nil, options = {})
bucket = bucket_name(bucket)
source_key = path!(bucket, key)
default_options = {'x-amz-copy-source' => source_key}
target_key = path!(bucket, copy_key)
returning put(target_key, default_options.merge(options)) do
acl(copy_key, bucket, acl(key, bucket)) if options[:copy_acl]
end
end
# Rename the object with key <tt>from</tt> to have key in <tt>to</tt>.
def rename(from, to, bucket = nil, options = {})
copy(from, to, bucket, options)
delete(from, bucket)
end
# Fetch information about the object with <tt>key</tt> from <tt>bucket</tt>. Information includes content type, content length,
# last modified time, and others.
#
# If the specified key does not exist, NoSuchKey is raised.
def about(key, bucket = nil, options = {})
response = head(path!(bucket, key, options), options)
raise NoSuchKey.new("No such key `#{key}'", bucket) if response.code == 404
About.new(response.headers)
end
# Checks if the object with <tt>key</tt> in <tt>bucket</tt> exists.
#
# S3Object.exists? 'kiss.jpg', 'marcel'
# # => true
def exists?(key, bucket = nil)
about(key, bucket)
true
rescue NoSuchKey
false
end
# Delete object with <tt>key</tt> from <tt>bucket</tt>.
def delete(key, bucket = nil, options = {})
# A bit confusing. Calling super actually makes an HTTP DELETE request. The delete method is
# defined in the Base class. It happens to have the same name.
super(path!(bucket, key, options), options).success?
end
# When storing an object on the S3 servers using S3Object.store, the <tt>data</tt> argument can be a string or an I/O stream.
# If <tt>data</tt> is an I/O stream it will be read in segments and written to the socket incrementally. This approach
# may be desirable for very large files so they are not read into memory all at once.
#
# # Non streamed upload
# S3Object.store('greeting.txt', 'hello world!', 'marcel')
#
# # Streamed upload
# S3Object.store('roots.mpeg', open('roots.mpeg'), 'marcel')
def store(key, data, bucket = nil, options = {})
validate_key!(key)
# Must build path before infering content type in case bucket is being used for options
path = path!(bucket, key, options)
infer_content_type!(key, options)
put(path, options, data) # Don't call .success? on response. We want to get the etag.
end
alias_method :create, :store
alias_method :save, :store
# All private objects are accessible via an authenticated GET request to the S3 servers. You can generate an
# authenticated url for an object like this:
#
# S3Object.url_for('beluga_baby.jpg', 'marcel_molina')
#
# By default authenticated urls expire 5 minutes after they were generated.
#
# Expiration options can be specified either with an absolute time since the epoch with the <tt>:expires</tt> options,
# or with a number of seconds relative to now with the <tt>:expires_in</tt> options:
#
# # Absolute expiration date
# # (Expires January 18th, 2038)
# doomsday = Time.mktime(2038, 1, 18).to_i
# S3Object.url_for('beluga_baby.jpg',
# 'marcel',
# :expires => doomsday)
#
# # Expiration relative to now specified in seconds
# # (Expires in 3 hours)
# S3Object.url_for('beluga_baby.jpg',
# 'marcel',
# :expires_in => 60 * 60 * 3)
#
# You can specify whether the url should go over SSL with the <tt>:use_ssl</tt> option:
#
# # Url will use https protocol
# S3Object.url_for('beluga_baby.jpg',
# 'marcel',
# :use_ssl => true)
#
# By default, the ssl settings for the current connection will be used.
#
# If you have an object handy, you can use its <tt>url</tt> method with the same objects:
#
# song.url(:expires_in => 30)
#
# To get an unauthenticated url for the object, such as in the case
# when the object is publicly readable, pass the
# <tt>:authenticated</tt> option with a value of <tt>false</tt>.
#
# S3Object.url_for('beluga_baby.jpg',
# 'marcel',
# :authenticated => false)
# # => http://s3.amazonaws.com/marcel/beluga_baby.jpg
def url_for(name, bucket = nil, options = {})
connection.url_for(path!(bucket, name, options), options) # Do not normalize options
end
def path!(bucket, name, options = {}) #:nodoc:
# We're using the second argument for options
if bucket.is_a?(Hash)
options.replace(bucket)
bucket = nil
end
'/' << File.join(bucket_name(bucket), name)
end
private
def validate_key!(key)
raise InvalidKeyName.new(key) unless key && key.size <= 1024
end
def infer_content_type!(key, options)
return if options.has_key?(:content_type)
if mime_type = MIME::Types.type_for(key).first
options[:content_type] = mime_type.content_type
end
end
end
class Value < String #:nodoc:
attr_reader :response
def initialize(response)
super(response.body)
@response = response
end
end
class About < Hash #:nodoc:
def initialize(headers)
super()
replace(headers)
metadata
end
def [](header)
super(header.to_header)
end
def []=(header, value)
super(header.to_header, value)
end
def to_headers
self.merge(metadata.to_headers)
end
def metadata
Metadata.new(self)
end
memoized :metadata
end
class Metadata < Hash #:nodoc:
HEADER_PREFIX = 'x-amz-meta-'
SIZE_LIMIT = 2048 # 2 kilobytes
def initialize(headers)
@headers = headers
super()
extract_metadata!
end
def []=(header, value)
super(header_name(header.to_header), value)
end
def [](header)
super(header_name(header.to_header))
end
def to_headers
validate!
self
end
private
attr_reader :headers
def extract_metadata!
headers.keys.grep(Regexp.new(HEADER_PREFIX)).each do |metadata_header|
self[metadata_header] = headers.delete(metadata_header)
end
end
def header_name(name)
name =~ Regexp.new(HEADER_PREFIX) ? name : [HEADER_PREFIX, name].join
end
def validate!
invalid_headers = inject([]) do |invalid, (name, value)|
invalid << name unless valid?(value)
invalid
end
raise InvalidMetadataValue.new(invalid_headers) unless invalid_headers.empty?
end
def valid?(value)
value && value.size < SIZE_LIMIT
end
end
attr_writer :value #:nodoc:
# Provides readers and writers for all valid header settings listed in <tt>valid_header_settings</tt>.
# Subsequent saves to the object after setting any of the valid headers settings will be reflected in
# information about the object.
#
# some_s3_object.content_type
# => nil
# some_s3_object.content_type = 'text/plain'
# => "text/plain"
# some_s3_object.content_type
# => "text/plain"
# some_s3_object.store
# S3Object.about(some_s3_object.key, some_s3_object.bucket.name)['content-type']
# => "text/plain"
include SelectiveAttributeProxy #:nodoc
proxy_to :about, :exclusively => false
# Initializes a new S3Object.
def initialize(attributes = {}, &block)
super
self.value = attributes.delete(:value)
self.bucket = attributes.delete(:bucket)
yield self if block_given?
end
# The current object's bucket. If no bucket has been set, a NoBucketSpecified exception will be raised. For
# cases where you are not sure if the bucket has been set, you can use the belongs_to_bucket? method.
def bucket
@bucket or raise NoBucketSpecified
end
# Sets the bucket that the object belongs to.
def bucket=(bucket)
@bucket = bucket
self
end
# Returns true if the current object has been assigned to a bucket yet. Objects must belong to a bucket before they
# can be saved onto S3.
def belongs_to_bucket?
!@bucket.nil?
end
alias_method :orphan?, :belongs_to_bucket?
# Returns the key of the object. If the key is not set, a NoKeySpecified exception will be raised. For cases
# where you are not sure if the key has been set, you can use the key_set? method. Objects must have a key
# set to be saved onto S3. Objects which have already been saved onto S3 will always have their key set.
def key
attributes['key'] or raise NoKeySpecified
end
# Sets the key for the current object.
def key=(value)
attributes['key'] = value
end
# Returns true if the current object has had its key set yet. Objects which have already been saved will
# always return true. This method is useful for objects which have not been saved yet so you know if you
# need to set the object's key since you can not save an object unless its key has been set.
#
# object.store if object.key_set? && object.belongs_to_bucket?
def key_set?
!attributes['key'].nil?
end
# Lazily loads object data.
#
# Force a reload of the data by passing <tt>:reload</tt>.
#
# object.value(:reload)
#
# When loading the data for the first time you can optionally yield to a block which will
# allow you to stream the data in segments.
#
# object.value do |segment|
# send_data segment
# end
#
# The full list of options are listed in the documentation for its class method counter part, S3Object::value.
def value(options = {}, &block)
if options.is_a?(Hash)
reload = !options.empty?
else
reload = options
options = {}
end
expirable_memoize(reload) do
self.class.stream(key, bucket.name, options, &block)
end
end
# Interface to information about the current object. Information is read only, though some of its data
# can be modified through specific methods, such as content_type and content_type=.
#
# pp some_object.about
# {"last-modified" => "Sat, 28 Oct 2006 21:29:26 GMT",
# "x-amz-id-2" => "LdcQRk5qLwxJQiZ8OH50HhoyKuqyWoJ67B6i+rOE5MxpjJTWh1kCkL+I0NQzbVQn",
# "content-type" => "binary/octet-stream",
# "etag" => "\"dc629038ffc674bee6f62eb68454ff3a\"",
# "date" => "Sat, 28 Oct 2006 21:30:41 GMT",
# "x-amz-request-id" => "B7BC68F55495B1C8",
# "server" => "AmazonS3",
# "content-length" => "3418766"}
#
# some_object.content_type
# # => "binary/octet-stream"
# some_object.content_type = 'audio/mpeg'
# some_object.content_type
# # => 'audio/mpeg'
# some_object.store
def about
stored? ? self.class.about(key, bucket.name) : About.new
end
memoized :about
# Interface to viewing and editing metadata for the current object. To be treated like a Hash.
#
# some_object.metadata
# # => {}
# some_object.metadata[:author] = 'Dave Thomas'
# some_object.metadata
# # => {"x-amz-meta-author" => "Dave Thomas"}
# some_object.metadata[:author]
# # => "Dave Thomas"
def metadata
about.metadata
end
memoized :metadata
# Saves the current object with the specified <tt>options</tt>. Valid options are listed in the documentation for S3Object::store.
def store(options = {})
raise DeletedObject if frozen?
options = about.to_headers.merge(options) if stored?
response = self.class.store(key, value, bucket.name, options)
bucket.update(:stored, self)
response.success?
end
alias_method :create, :store
alias_method :save, :store
# Deletes the current object. Trying to save an object after it has been deleted with
# raise a DeletedObject exception.
def delete
bucket.update(:deleted, self)
freeze
self.class.delete(key, bucket.name)
end
# Copies the current object, given it the name <tt>copy_name</tt>. Keep in mind that due to limitations in
# S3's API, this operation requires retransmitting the entire object to S3.
def copy(copy_name, options = {})
self.class.copy(key, copy_name, bucket.name, options)
end
# Rename the current object. Keep in mind that due to limitations in S3's API, this operation requires
# retransmitting the entire object to S3.
def rename(to, options = {})
self.class.rename(key, to, bucket.name, options)
end
def etag(reload = false)
return nil unless stored?
expirable_memoize(reload) do
reload ? about(reload)['etag'][1...-1] : attributes['e_tag'][1...-1]
end
end
# Returns the owner of the current object.
def owner
Owner.new(attributes['owner'])
end
memoized :owner
# Generates an authenticated url for the current object. Accepts the same options as its class method
# counter part S3Object.url_for.
def url(options = {})
self.class.url_for(key, bucket.name, options)
end
# Returns true if the current object has been stored on S3 yet.
def stored?
!attributes['e_tag'].nil?
end
def ==(s3object) #:nodoc:
path == s3object.path
end
def path #:nodoc:
self.class.path!(
belongs_to_bucket? ? bucket.name : '(no bucket)',
key_set? ? key : '(no key)'
)
end
# Don't dump binary data :)
def inspect #:nodoc:
"#<%s:0x%s '%s'>" % [self.class, object_id, path]
end
private
def proxiable_attribute?(name)
valid_header_settings.include?(name)
end
def valid_header_settings
%w(cache_control content_type content_length content_md5 content_disposition content_encoding expires)
end
end
end
end
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