As we are improving // foss.events today we wonder why #Mastodon shows a wrong #preview and how to fix it?
It currently always shows "Everything in a nutshell about FOSS Hackathon 2025 on // foss.events" - which is the lates addition we have, although the event is for example about PyCamp España (see screenshots)
Even though the event has specified otherwise in its #OpenGraph metadata?
I think the data is cached in connection with the url. Same with my website. When I already posted a link to mastodon and mastodon created the preview, the preview is kept even if I change the picture.
@tinoeberl but in this case it is not a repost of an event, but whenever we post a new event it always shows the wrong description
@tinoeberl @foss_events I think the same. The URL has to be the permalink of the URL you share. Probably, things are cached based on this URL.
Source: "og:url - The canonical URL of your object that will be used as its permanent ID in the graph, e.g., "https://www.imdb.com/title/tt0117500/"."
@mxmehl @tinoeberl we were wondering as well as it is even more weird:
despite that the open graph meta data - as you see - provides the home page as URL, the preview correctly links to the event that it refers to?
So maybe in the end it does not take the open graph information at all but uses the information from somewhere else?
@foss_events @tinoeberl Well, it takes the link you share in your post. This does not necessarily have to be the permalink you provide in og:url, if you think about tracking links etc.
@mxmehl @tinoeberl ok, we just adjusted as attached, let's wait for the next post and thank you very much for your help!
@foss_events @tinoeberl Let's see ;) You could also adapt the og:title to the event title