AWS S3 ListObjectsV2 returns 'folder' as object

Question content

I'm trying to list all files under a specific directory in an s3 bucket (I know s3 doesn't really have a directory.).

The structure is:

bucket-name: folder1/folder2/folder3/file

So in the s3 world I believe this would just store a file named above.

This is my code:

params := &s3.listobjectsv2input{
        bucket: aws.string(os.getenv("s3_user_bucket")),
        prefix: aws.string(key + loc[0] + "/"),
    }

    resp, _ := svc.listobjectsv2(params)

resp contains the file I expect, and the "directory" it is stored in:

contents: [{
      etag: "\"tag\"",
      key: "folder1/folder2/folder3/",
      lastmodified: 2023-03-02 17:32:17 +0000 utc,
      size: 0,
      storageclass: "standard"
    },{
      etag: "\"tag\"",
      key: "folder1/folder2/folder3/file",
      lastmodified: 2023-03-02 17:32:30 +0000 utc,
      size: 106808,
      storageclass: "standard"
    }],
  istruncated: false,
  keycount: 2,
  maxkeys: 1000,
  name: "bucket",
  prefix: "folder1/folder2/folder3/"
}

I also tried:

params := &s3.listobjectsv2input{
        bucket: aws.string(os.getenv("s3_user_bucket")),
        prefix: aws.string(key + loc[0] + "/"),
        delimiter: aws.string("/"),
    }

    resp, _ := svc.listobjectsv2(params)

But the result is the same.

This is the result of the parameters:

Params:  {
  Bucket: "BUCKET",
  Prefix: "Folder1/Folder2/Folder3/"
}

Correct answer

I assume you are asking why there is a directory returned as an object.

You are absolutely right, amazon s3 does not use directories . Instead, the object's filename (key) is the full path, including the filename. There is no need to create a directory before creating an object on a specific path.

However, if someone clicks the Create Folder button in the s3 management console, it will create a zero-length object with the name of the directory. This "forces" the directory to appear (because there is an object in it), but it is actually a zero-length object.

View your listing results:

Contents: [{
      ETag: "\"TAG\"",
      Key: "Folder1/Folder2/Folder3/",
      LastModified: 2023-03-02 17:32:17 +0000 UTC,
      Size: 0,
      StorageClass: "STANDARD"

You'll notice that it says size: 0, so this is a zero-length object.

If you want to omit these types of files from the list, just skip the zero-length objects in your code.

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