How are comments federated? (lemmy.world)

submitted 1 year ago by quest@lemmy.world to c/fediverse@lemmy.world

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I'm trying to figure out how to get the comments of a post given a link to it using ActivityPub.

Based on reading the ActivityPub spec, I thought comments were federated via the replies key of the ActivityPub Object.

This works for Mastodon posts, but not for Lemmy (nor Pleroma). As an example

curl -H "Accept: application/activity+json" https://lemmy.my.id/post/79514 | jq

doesn't contain a replies key. Yet the comments are federated to Mastodon somehow.

What is going on? How can I get the comment?

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[-] r00ty@kbin.life 0 points 1 year ago

You can see the hierarchy above not below.

You might get a like. It looks like:

like: [
    "id" => "https://lemmy.one/activities/like/7d0ef24f-755f-48dd-9b37-ea42041cb34e",
    "actor" => "https://lemmy.one/u/Matt",
    "object" => "https://lemmy.procrastinati.org/comment/146844",
    "type" => "Like",
    "audience" => "https://lemdro.id/c/android"
]

In the object property you see the comment. If you visit that you'll get among the rest of the json for the comment

"inReplyTo": "https://lemmy.world/comment/1269475",

And again

"inReplyTo": "https://lemdro.id/post/77457",

Now you have the hierarchy from the like's comment to the post. Not the rest of the tree, enough to render the comment in context though.

[-] CommunityLinkFixer@lemmings.world 1 points 1 year ago

Hi there! Looks like you linked to a Lemmy community using a URL instead of its name, which doesn't work well for people on different instances. Try fixing it like this: !android@lemdro.id

[-] quest@lemmy.world 1 points 1 year ago

I understand exactly what you're saying; you can get the parents but not the replies in that situation.

I'm just saying that in your situation (e.g. someone I follow on Mastodon likes a Lemmy post) it would be convenient for me as a user to be able to view the replies to that Lemmy post, but I cannot necessarily do that because Lemmy does not include replies.