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[diagnostics_channel] support body received? #1342
Description
This would solve...
In a library I am working on, they had 2 events (request & response) that would fire before and after a request was made. The purpose of these events was for analytics (ie. receiving a "weird" response code and checking the body). With undici, I'm hoping that these events can be removed entirely and instead use the diagnostics_channel support (the library only supports v16.9.0+).
The implementation should look like...
In the request property, the body is sent but under a symbol property and uncloned. Exposing it publicly (maybe under bodyReceived or some other name) and cloning it so it can be used twice would be exactly what I need. Receiving a buffer would also be very useful.
Since it is using request, rather than fetch, it is using a node Readable stream so we can't just tee the stream.
I have also considered...
Additional context
The implementation previously used was not performant and didn't need to be because it was only supposed to be used when something majorly messed up.
Activity
mcollina commentedon Apr 17, 2022
You can't clone a node stream. Here is a module that implements that functionality in case you need it: https://www.npmjs.com/package/cloneable-readable.
Overall everything that improves diagnostics_channel is great. However that's a low level instrument, so cloning would be off the table.
KhafraDev commentedon Apr 17, 2022
I think with a bodySent property it could be left to the user to use your package... although that might not be the greatest UX?
mcollina commentedon Apr 17, 2022
Would you mind to assemble a prototype? You have definitely researched this more than me.
KhafraDev commentedon Apr 18, 2022
Exposing the ReadableStream body can be done like so (not cloned)
Unsure if it's even useful as it probably would suffer from race conditions (consuming the body somewhere else before cloning)... I'll look into it more
KhafraDev commentedon Apr 18, 2022
Found a much better way to do this, I'll make a PR soon to see what you think.
[-][diagnostics_channel] support body received in `undici:request:trailers`[/-][+][diagnostics_channel] support body received?[/+]DEVTomatoCake commentedon Sep 6, 2023
Is there any update regarding this? If not, is there any alternative solution without modifying undici or a package source code?
I would like to see the sent and received body for debugging, as error messages returned by other packages usually don't include the full body.
There's
undici:request:bodySent, but apparently it only works for some kind of requests (might be usingrequestvsfetch, it looks like the latter only returns[object AsyncGenerator]instead of the body buffer which I'm unable to convert to a string containing the body).metcoder95 commentedon Sep 7, 2023
You can always use
interceptorsfor that. I'm not sure if enabling diagnostics to dig into the body content of the response might be a good idea given the security vectors around, but definitely knowing when the body is received and possible auxiliary data of the response is always helpfulDEVTomatoCake commentedon Sep 7, 2023
I don't see how this would help me as I would still have to modify the source code to add the interceptor there, unless you're able to apply this globally which, if possible, I haven't been able to figure out.
metcoder95 commentedon Sep 7, 2023
You can apply it by creating a custom
Clientand setting it assetGlobalDispatcher. The interceptors are added to theClientand any with no custom client (eitherUndici.requestorfetch) will have these interceptors.It can help apply, more or less, what you are looking for
DEVTomatoCake commentedon Sep 8, 2023
Looks good, but as I have to specify an URL/domain when creating the Client, using this breaks all requests to URLs that aren't on the same domain as the one specified... However, this'll work for now, thank you so far!