class AWS::S3::S3Object
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 binary/octet-stream
.
If you want to override this, you can explicitly indicate what content type the object should have with the :content_type
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 stream
:
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 value
won't redownload the file unless you tell the object to reload its value
:
# 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 content_type
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 limitations 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 bevy of information about an object can be had using the about
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"}
Public Class Methods
Fetch information about the object with key
from bucket
. Information includes content type, content length, last modified time, and others.
If the specified key does not exist, NoSuchKey is raised.
# File lib/aws/s3/object.rb 202 def about(key, bucket = nil, options = {}) 203 response = head(path!(bucket, key, options), options) 204 raise NoSuchKey.new("No such key `#{key}'", bucket) if response.code == 404 205 About.new(response.headers) 206 end
Makes a copy of the object with key
to copy_key
, preserving the ACL of the existing object if the :copy_acl
option is true (default false).
# File lib/aws/s3/object.rb 182 def copy(key, copy_key, bucket = nil, options = {}) 183 bucket = bucket_name(bucket) 184 source_key = path!(bucket, key) 185 default_options = {'x-amz-copy-source' => source_key} 186 target_key = path!(bucket, copy_key) 187 returning put(target_key, default_options.merge(options)) do 188 acl(copy_key, bucket, acl(key, bucket)) if options[:copy_acl] 189 end 190 end
Delete object with key
from bucket
.
# File lib/aws/s3/object.rb 220 def delete(key, bucket = nil, options = {}) 221 # A bit confusing. Calling super actually makes an HTTP DELETE request. The delete method is 222 # defined in the Base class. It happens to have the same name. 223 super(path!(bucket, key, options), options).success? 224 end
Checks if the object with key
in bucket
exists.
S3Object.exists? 'kiss.jpg', 'marcel' # => true
# File lib/aws/s3/object.rb 212 def exists?(key, bucket = nil) 213 about(key, bucket) 214 true 215 rescue NoSuchKey 216 false 217 end
Returns the object whose key is name
in the specified bucket. If the specified key does not exist, a NoSuchKey exception will be raised.
# File lib/aws/s3/object.rb 145 def find(key, bucket = nil) 146 # N.B. This is arguably a hack. From what the current S3 API exposes, when you retrieve a bucket, it 147 # provides a listing of all the files in that bucket (assuming you haven't limited the scope of what it returns). 148 # Each file in the listing contains information about that file. It is from this information that an S3Object is built. 149 # 150 # If you know the specific file that you want, S3 allows you to make a get request for that specific file and it returns 151 # the value of that file in its response body. This response body is used to build an S3Object::Value object. 152 # If you want information about that file, you can make a head request and the headers of the response will contain 153 # information about that file. There is no way, though, to say, give me the representation of just this given file the same 154 # way that it would appear in a bucket listing. 155 # 156 # When fetching a bucket, you can provide options which narrow the scope of what files should be returned in that listing. 157 # 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 158 # the specified marker according to alphabetic order. Another option is <tt>max-keys</tt> which defaults to 1000 but allows you 159 # 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 160 # *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 161 # 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 162 # return 'c', not 'b'. 163 # 164 # 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 165 # the desired object's key, which functionally makes the key ordered one degree higher than the desired object key according to 166 # 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 167 # something incorrect. 168 169 # 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, 170 # the key on S3 will have been normalized 171 key = key.remove_extended unless key.valid_utf8? 172 bucket = Bucket.find(bucket_name(bucket), :marker => key.previous, :max_keys => 1) 173 # If our heuristic failed, trigger a NoSuchKey exception 174 if (object = bucket.objects.first) && object.key == key 175 object 176 else 177 raise NoSuchKey.new("No such key `#{key}'", bucket) 178 end 179 end
Initializes a new S3Object.
# File lib/aws/s3/object.rb 420 def initialize(attributes = {}, &block) 421 super 422 self.value = attributes.delete(:value) 423 self.bucket = attributes.delete(:bucket) 424 yield self if block_given? 425 end
Rename the object with key from
to have key in to
.
# File lib/aws/s3/object.rb 193 def rename(from, to, bucket = nil, options = {}) 194 copy(from, to, bucket, options) 195 delete(from, bucket) 196 end
When storing an object on the S3 servers using S3Object.store
, the data
argument can be a string or an I/O stream. If data
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')
# File lib/aws/s3/object.rb 235 def store(key, data, bucket = nil, options = {}) 236 validate_key!(key) 237 # Must build path before infering content type in case bucket is being used for options 238 path = path!(bucket, key, options) 239 infer_content_type!(key, options) 240 241 put(path, options, data) # Don't call .success? on response. We want to get the etag. 242 end
# File lib/aws/s3/object.rb 137 def stream(key, bucket = nil, options = {}, &block) 138 value(key, bucket, options) do |response| 139 response.read_body(&block) 140 end 141 end
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 :expires
options, or with a number of seconds relative to now with the :expires_in
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 :use_ssl
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 url
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 :authenticated
option with a value of false
.
S3Object.url_for('beluga_baby.jpg', 'marcel', :authenticated => false) # => http://s3.amazonaws.com/marcel/beluga_baby.jpg
# File lib/aws/s3/object.rb 290 def url_for(name, bucket = nil, options = {}) 291 connection.url_for(path!(bucket, name, options), options) # Do not normalize options 292 end
Returns the value of the object with key
in the specified bucket.
Conditional GET options¶ ↑
-
:if_modified_since
- Return the object only if it has been modified since the specified time, otherwise return a 304 (not modified). -
:if_unmodified_since
- Return the object only if it has not been modified since the specified time, otherwise raise PreconditionFailed. -
:if_match
- Return the object only if its entity tag (ETag) is the same as the one specified, otherwise raise PreconditionFailed. -
:if_none_match
- Return the object only if its entity tag (ETag) is different from the one specified, otherwise return a 304 (not modified).
Other options¶ ↑
-
:range
- Return only the bytes of the object in the specified range.
# File lib/aws/s3/object.rb 133 def value(key, bucket = nil, options = {}, &block) 134 Value.new(get(path!(bucket, key, options), options, &block)) 135 end
Private Class Methods
# File lib/aws/s3/object.rb 309 def infer_content_type!(key, options) 310 return if options.has_key?(:content_type) 311 if mime_type = MIME::Types.type_for(key).first 312 options[:content_type] = mime_type.content_type 313 end 314 end
# File lib/aws/s3/object.rb 305 def validate_key!(key) 306 raise InvalidKeyName.new(key) unless key && key.size <= 1024 307 end
Public Instance Methods
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
# File lib/aws/s3/object.rb 512 def about 513 stored? ? self.class.about(key, bucket.name) : About.new 514 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.
# File lib/aws/s3/object.rb 441 def belongs_to_bucket? 442 !@bucket.nil? 443 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.
# File lib/aws/s3/object.rb 429 def bucket 430 @bucket or raise NoBucketSpecified 431 end
Sets the bucket that the object belongs to.
# File lib/aws/s3/object.rb 434 def bucket=(bucket) 435 @bucket = bucket 436 self 437 end
Copies the current object, given it the name copy_name
. Keep in mind that due to limitations in S3's API, this operation requires retransmitting the entire object to S3.
# File lib/aws/s3/object.rb 552 def copy(copy_name, options = {}) 553 self.class.copy(key, copy_name, bucket.name, options) 554 end
Deletes the current object. Trying to save an object after it has been deleted with raise a DeletedObject exception.
# File lib/aws/s3/object.rb 544 def delete 545 bucket.update(:deleted, self) 546 freeze 547 self.class.delete(key, bucket.name) 548 end
# File lib/aws/s3/object.rb 562 def etag(reload = false) 563 return nil unless stored? 564 expirable_memoize(reload) do 565 reload ? about(reload)['etag'][1...-1] : attributes['e_tag'][1...-1] 566 end 567 end
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.
# File lib/aws/s3/object.rb 449 def key 450 attributes['key'] or raise NoKeySpecified 451 end
Sets the key for the current object.
# File lib/aws/s3/object.rb 454 def key=(value) 455 attributes['key'] = value 456 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?
# File lib/aws/s3/object.rb 463 def key_set? 464 !attributes['key'].nil? 465 end
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"
# File lib/aws/s3/object.rb 526 def metadata 527 about.metadata 528 end
Returns the owner of the current object.
# File lib/aws/s3/object.rb 570 def owner 571 Owner.new(attributes['owner']) 572 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.
# File lib/aws/s3/object.rb 558 def rename(to, options = {}) 559 self.class.rename(key, to, bucket.name, options) 560 end
Saves the current object with the specified options
. Valid options are listed in the documentation for S3Object::store
.
# File lib/aws/s3/object.rb 532 def store(options = {}) 533 raise DeletedObject if frozen? 534 options = about.to_headers.merge(options) if stored? 535 response = self.class.store(key, value, bucket.name, options) 536 bucket.update(:stored, self) 537 response.success? 538 end
Returns true if the current object has been stored on S3 yet.
# File lib/aws/s3/object.rb 582 def stored? 583 !attributes['e_tag'].nil? 584 end
Generates an authenticated url for the current object. Accepts the same options as its class method counter part S3Object.url_for
.
# File lib/aws/s3/object.rb 577 def url(options = {}) 578 self.class.url_for(key, bucket.name, options) 579 end
Lazily loads object data.
Force a reload of the data by passing :reload
.
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
.
# File lib/aws/s3/object.rb 481 def value(options = {}, &block) 482 if options.is_a?(Hash) 483 reload = !options.empty? 484 else 485 reload = options 486 options = {} 487 end 488 expirable_memoize(reload) do 489 self.class.stream(key, bucket.name, options, &block) 490 end 491 end
Private Instance Methods
# File lib/aws/s3/object.rb 603 def proxiable_attribute?(name) 604 valid_header_settings.include?(name) 605 end
# File lib/aws/s3/object.rb 607 def valid_header_settings 608 %w(cache_control content_type content_length content_md5 content_disposition content_encoding expires) 609 end