Empty JSON Payload Causes rest_invalid_json

[GamerZ]

The rest_invalid_json error was introduced in #38547 which is meant to detect defect json in body. However, if a empty body is used, this is marked as invalid as well.

There are scenarios where empty body are used especially when deleting an item.

For example calling a DELETE method on a custom endpoint like the below means deleting the ID 1 from the item resource. There is no need to pass in any unnecessary body content.

DELETE /wp-json/custom-endppint/item/1

[jnylen0]

#39166 was marked as a duplicate.

[jnylen0]

Hi @GamerZ, thanks for reporting this. @peterigz seems to have reported the same issue in #39166.

From the ​relevant code it looks like this only happens if you send Content-Type: application/json. Is it an option for either of you to omit this header from your requests?

[peterigz]

Thanks for looking. I'm using ​https://github.com/woocommerce/wc-api-php, see here the relevent headers being generated: ​https://github.com/woocommerce/wc-api-php/blob/master/src/WooCommerce/HttpClient/HttpClient.php#L186

Maybe I should raise the issue over there?

[jnylen0]

Yes, that would be good.

[JPry]

Fix + tests

[GamerZ]

@jnylen0 changing the Content-Type header will work but it feels like it is not the right way of doing it.

For the company I work at, our Content-Type defaults to application/json for most requests.

[jnylen0]

Discussed a bit ​in Slack, technically the empty string is not valid JSON but this was a backwards compatibility break so we'll fix it in core.

[GamerZ]

Awesome thanks @jnylen0 !

[mikejolley]

Thanks for patching @jnylen0. I use Insomnia client on Mac and that triggers it if you leave JSON selected as content type. ​https://dl.dropboxusercontent.com/s/lu8ftrfxwaa94ks/2016-12-08%20at%2010.19.png Glad it wasn't just me :)

[boonebgorges]

I just ran into this as well, in my case with a GET request.

I defer to the API team on this, but I wonder if a narrower fix might be to skip body parsing (or allow empty body) for methods that don't specifically support a message-body. This seems like it would jibe better with RFC 2616, which says that servers should ignore the body for these request types. ​https://tools.ietf.org/html/rfc2616#section-4.3

[jnylen0]

I defer to the API team on this, but I wonder if a narrower fix might be to skip body parsing (or allow empty body) for methods that don't specifically support a message-body.

I'm not opposed to it, but @boonebgorges let's do that in a separate ticket.

The issue being discussed here was introduced in 4.7; the change you're proposing would date back to 4.4.

Edit: Also, this wouldn't fix the issue reported here for POST and other methods that do support a body.

[jnylen0]

In 39594:

REST API: Do not error on empty JSON body

It's fairly common for clients to send Content-Type: application/json with an
empty body. While technically not valid JSON, we've historically supported
this behaviour, so it shouldn't cause an error.

Props JPry.
Fixes #39150.

[jnylen0]

Needs to be ported to 4.7 branch.

[jnylen0]

#39284 was marked as a duplicate.

[dd32]

In 39609:

REST API: Do not error on empty JSON body

It's fairly common for clients to send Content-Type: application/json with an
empty body. While technically not valid JSON, we've historically supported
this behaviour, so it shouldn't cause an error.

Props JPry, jnylen0.
Merges [39594] to the 4.7 branch.
Fixes #39150.