使用 GCP PHP 客户端库创建文件夹

Question

I started learning Google Cloud Storage PHP Client Library through documentation given by Google. But following questions are uncleared.

1. How to create a folder in a bucket?
2. How to create a folder in a folder?
3. How to list all the files in a folder?

I have learnt that folders are nothing but objects with "/" at the end of their name. Also we can upload an object using $bucket->upload() method to upload an object. This method needs a path of file so it is creating a trouble to create a folder

Answer 1

Folders do not actually exist in Cloud Storage Buckets. The namespace is flat. The impression of folders is emulated by the Google Cloud Console and other tools. The files /MyFolder/test.txt and /YourFolder/test.txt are at the same level (same directory) in the bucket (at the root level) - I am ignoring object name hashing. Tools use the / character as a separator (delimitor) to emulate folders.

How Subdirectories Work

When working with the Google Cloud Storage REST API, directories are listed by using a delimeter=/ and specifying a prefix for the directory name, example:

https://www.googleapis.com/storage/v1/b/MYBUCKETNAME/o?prefix=MyDirectory/?delimiter=/

This URL informs the REST API that you want to list the object names that start with MyDirectory/ breaking on object names that continue after the next delimiter, example:

MyDirectory/file1.txt
MyDirectory/file2.txt
MyDirectory/something/file3.txt

Note that nowhere in the namespace is the object name (directory) MyDirectory or MyDirectory/something stored. That is just derived from the object names using prefixes and delimiters.

The above URL will list the first two objects. The third will be skipped.

The API returns JSON data, and there are two types of data returned:

1. items , which return the object names that start with prefix and do not contain a delimiter after the prefix.
2. prefixes , which returns the object names truncated by the delimiter - which provides the equivalent of directory names.

In other words, the illusion of directories and their contents is just a fancy parsing trick performed by the Google Cloud Storage API.

Answer 2

Answer to question1 : Creating empty folders is possible only via cloud console. You cannot create empty folder in a GCP bucket via SDK functions. Suppose if you wanted to create, /test folder in a bucket, upload a file named /test/file.txt . Make sure that the files you upload later in that /test folder to be other than file.txt

Answer to question2 : Almost identical to first question except paths

Answer to question3 : Listing items in a particular directory can be done using extra parameters like delimiters, prefixes provided by GCP SDK.