Bug #46600 [NoF]: "_empty_" key in objects (see #41504)

From: Date: Wed, 23 Mar 2016 07:43:18 +0000
Subject: Bug #46600 [NoF]: "_empty_" key in objects (see #41504)
References: 1  Groups: php.bugs 
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Edit report at https://bugs.php.net/bug.php?id=46600&edit=1

 ID:                 46600
 Updated by:         yohgaki@php.net
 Reported by:        Matt at mpcm dot com
 Summary:            "_empty_" key in objects (see #41504)
 Status:             No Feedback
 Type:               Bug
 Package:            JSON related
 Operating System:   *
 PHP Version:        5CVS, 6CVS (2008-11-18)
 Block user comment: N
 Private report:     N

 New Comment:

Property names are defined as "string" and "string" is defined as follows.

https://tools.ietf.org/html/rfc7159#section-7

      string = quotation-mark *char quotation-mark

      char = unescaped /
          escape (
              %x22 /          ; "    quotation mark  U+0022
              %x5C /          ; \    reverse solidus U+005C
              %x2F /          ; /    solidus         U+002F
              %x62 /          ; b    backspace       U+0008
              %x66 /          ; f    form feed       U+000C
              %x6E /          ; n    line feed       U+000A
              %x72 /          ; r    carriage return U+000D
              %x74 /          ; t    tab             U+0009
              %x75 4HEXDIG )  ; uXXXX                U+XXXX

      escape = %x5C              ; \

      quotation-mark = %x22      ; "

      unescaped = %x20-21 / %x23-5B / %x5D-10FFFF


https://tools.ietf.org/html/rfc7159#section-4

Object property name should be unique. i.e. "The names within an object SHOULD be unique."

I cannot tell if "" is valid or not. Is it valid JSON?

BTW, the name for empty elements should be "__empty" or "__empty__" as we
usually "__name" or "__name__" for reserved names.


Previous Comments:
------------------------------------------------------------------------
[2016-03-23 02:49:25] ofbeaton at gmail dot com

So I just ran into this problem while making a satis repository script for composer. I don't
see a good solution.

If I $composerJson = json_decode($composerJson, true) into associative arrays,
manipulate it, then json_encode($composerJson) then my 
  "require-dev": {}
turns into
  "require-dev": []
which composer chokes on. So obviously I can't read the composer file as associative arrays!
That isn't this bug, I just want to show upfront that using the associative array parameter on
my json_decode cannot solve my problem.

So I do: $composerJson = json_decode($composerJson, false) and turn it into objects
like this thread talks about. Except the most common composer.json contains something like this:
  "autoload": {
    "psr-4": {
      "": "src/"
    }
  }

it reads it in fine, but when I do json_encode($composerJson) again... I get:
  "autoload": {
    "psr-4": {
      "_empty_": "src/"
    }
  }

which composer then chokes on because of course "_empty_" has a different meaning than
"".

So I'm stuck doing a json_encode then using a hack, $composerJson =
str_replace('"_empty_":', '"":', $composerJson)
before writing it to file again.

The _empty_ key does not seem to me to be the right answer here. Should composer change the way
composer files for virtually all projects be written? Is this a composer bug?

Or should json_encode and json_decode objects reproduce a blank key?

I hope the answer is the later, but I cannot say for sure.

------------------------------------------------------------------------
[2016-01-25 14:56:31] ajf@php.net

This is arguably not a bug since you can't have objects with empty property names, so this is
necessary to allow decoding JSON objects with empty keys. However, that's a rather arbitrary
restriction. If we removed it, we could fix this.

------------------------------------------------------------------------
[2014-01-14 18:50:41] matt at mpcm dot com

Last post was a bad example, this is the actual output:
as object: {"_empty_":"c"}
as array: {"_empty_":"a","":"c"}

------------------------------------------------------------------------
[2014-01-14 18:48:23] matt at mpcm dot com

With an output of:
as object: {"_empty_":"c"}
as array: {"_empty_":"b","":"c"}

------------------------------------------------------------------------
[2014-01-14 18:47:27] matt at mpcm dot com

To illustrate the current collision state, as this came up on the JSMentors list recently.

<?php
$a =
'{"_empty_":"a","":"b","":"c"}';
echo "as object: " . json_encode(json_decode($a));
echo "\n";
echo "as array: " . json_encode(json_decode($a, true));

PHP 5.4.17 (cli) (built: Aug 25 2013 02:03:38)
Copyright (c) 1997-2013 The PHP Group
Zend Engine v2.4.0, Copyright (c) 1998-2013 Zend Technologies

------------------------------------------------------------------------


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