fix proxy body write condition

[TheSharpieOne]

AFAICT the current condition can never be true?

With this change, it will be true when proxyObject.statusCode is not 304

[robmcguinness]

LGTM

[GoPro16]

This PR broke proxying as a whole. I think it should have been status === 304

[TheSharpieOne]

but 304 indicates that there would be no body and nothing to rewrite? Checking that it is not 304 before attempting to rewrite the body makes sense. Checking that it has to be 304 in order to perform the rewrite doesn't make sense.

https://httpstatuses.com/304

there is no need for the server to transfer a representation of the target resource because the request indicates that the client, which made the request conditional, already has a valid representation; the server is therefore redirecting the client to make use of that stored representation as if it were the payload of a 200 OK response

Also, I made this change locally (since I needed it to rewrite stuff in the body) and it worked fine for me. Previously it was not rewriting the body as I believe it was supposed to so I went looking and found this.

[GoPro16]

What http client are you using to fetch axios? We were getting errors with all our service calls.

net::ERR_CONTENT_LENGTH_MISMATCH 200 (OK)

That to me indicates we successfully rewrote the payload but the content length didn't get auto updated using the node module.

From looking at it with @robmcguinness it seems like the middleware was added but the logic never worked for 2 years which is why we didn't run into this error the first time we added it is what I am thinking

Sidenote

I reverted it for now and commented out the logic until we can find the issue that was happening and fix it for good.

[TheSharpieOne]

Yeah, I am using axios. Maybe some coincidence that the lengths matched for the origin and the rewrite in my case.
It looks like the server I am proxying to doesn't send content-length header...
Actually, it probably sends the content-length, but the node-http-proxy-json lib removes it before sending: https://github.com/langjt/node-http-proxy-json/blob/07d9c270ca941e3d39e32a51f49e5eba0a6d200f/index.js#L23
Either way, the logic should be right, just need to get it to also rewrite the length header.

[GoPro16]

Created an issue so we don't lose track of this

[TheSharpieOne]

You only need to bump the version of node-http-proxy-json. Looks like the one you were using was really old.

[robmcguinness]

It also appears the lib handles empty payloads now langjt/node-http-proxy-json@9b9f7d3