Modificatori di tema: una breve introduzione

Con l’aumentare dell’ambizione dei temi, abbiamo cercato modi per consentire loro di manipolare il comportamento fondamentale del server-side. Sebbene non otterranno mai lo stesso livello di controllo dei plugin, possiamo fornire alcuni hook predefiniti che i temi possono manipolare.

Presentazione: modificatori di tema :partying_face:

Sono specificati utilizzando la chiave modifiers nel file about.json del tema.

Per un elenco aggiornato al 100% dei modificatori, controlla lo schema del database in fondo a theme_modifier_set.rb, ma ecco un breve riepilogo di ciò che abbiamo finora:

  • serialize_topic_excerpts boolean (default false) - includi sempre gli estratti quando serializzi gli elenchi di argomenti

  • csp_extensions array di stringhe - aggiungi direttive alla CSP. Funziona allo stesso modo del vecchio metodo di impostazione del tema “extend_content_security_policy”. Ma ricorda, i tag \u003cscript src=\"\"\u003e semplici sono consentiti automaticamente.

  • svg_icons array di stringhe - un elenco di icone che dovrebbero essere incluse nel sottoinsieme di icone

  • topic thumbnails array di dimensioni - richiedi risoluzioni aggiuntive nel set di miniature degli argomenti. Nota che vengono generate in modo asincrono, quindi devi ricorrere all’immagine originale se la dimensione richiesta non è fornita. Maggiori informazioni disponibili nel messaggio di commit

  • serialize_post_user_badges array di stringhe - un elenco di nomi di badge (che corrispondono alle voci nella tabella dei badge) da serializzare insieme ai dati dei post. Quando configurato, il sistema include i badge utente specificati con ogni post per il rendering lato client.

Un tema che fa un uso intensivo di questi nuovi hook è Topic List Thumbnails - controlla il codice per vedere come funziona.

Modificatori dipendenti dalle impostazioni

I modificatori di tema possono anche essere configurati per prelevare il loro valore da un’impostazione del tema, consentendo agli operatori del sito di sovrascrivere il comportamento del modificatore senza modificare il codice del tema. Per rendere un modificatore dipendente da un’impostazione, usa questa sintassi nel tuo about.json:

{
  "modifiers": {
    "modifier_name": {
      "type": "setting",
      "value": "setting_name"
    }
  }
}

Ad esempio, se hai un’impostazione del tema chiamata show_excerpts e vuoi che controlli il modificatore serialize_topic_excerpts:

In settings.yml:

show_excerpts:
  default: false

In about.json:

{
  "modifiers": {
    "serialize_topic_excerpts": {
      "type": "setting",
      "value": "show_excerpts"
    }
  }
}

Quando l’impostazione show_excerpts viene modificata, il valore del modificatore si aggiornerà automaticamente per corrispondere. Ciò fornisce flessibilità agli operatori del sito per personalizzare il comportamento del tema tramite l’interfaccia utente di amministrazione.


Questo documento è controllato in versione - suggerisci modifiche su github.

35 Mi Piace

David, probably a bit lazy of me to ask but is there any way to access this in a plugin:

Themes can request additional thumbnail sizes by using a modifier in their about.json file:

I will be attempting to migrate the TLP plugin to this new schema and it would be good to have the same access to features from a plugin, at least in the meantime.

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There isn’t at the moment, but I’ll look into it :eyes:

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David, what’s the right approach for BULK recreation of thumbnails?

I’ve just tried utilising on one of my sites and it seems to have processed about 10% of the Topics … then given up (or turned its nose up at the rest). Why I think it’s the former is that the Topics for whom Thumbnails were produced were the latest 10%.

Rebaking posts doesn’t seem to cut it. In fact, I did run a bulk rebake and wonder if that upset it …

I notice that image_url can be populated, but there are no thumbnails.

Any advice, appreciated!

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That column doesn’t do anything, and will be dropped very soon. image_upload_id is the one you want.

There should be no need for this. I deliberately designed it so that people can install new themes without having to mess around on the console. Thumbnails are generated asynchronously when needed. For example:

  • you add a new theme, which requests new resolutions
  • a user requests a topic, we serve the thumbnails that exist. If any sizes don’t exist, we schedule a sidekiq job.
  • next time someone requests the topic, the correct thumbnails will exist

If the requested thumbnail size is larger than the original, we won’t bother generate the thumbnail.

So the critical thing to bear in mind for this to work is:

There’s an example of this fallback logic in the thumbnail theme component I made - feel free to steal logic from there.

5 Mi Piace

The fallback is serialised as thumbnailsl[0]? Yes, I’m already handling that. (nice implementation btw, very easy to handle)

Is it possible some images are ‘not making the grade’ or fitting the criteria?

The behaviour we have in the TLP plugin will pick up one-box thumbnails. That’s not happening in every case here I think.

For example, if you get time, take a look at these examples:

I don’t think these thumbnails make the cut. The thumbnails are serialized as null

Yes that’s deliberate - we had a number of requests to remove small onebox thumbnails. For example, people were ending up with their github avatar as a topic thumbnail - which is rarely intended

https://github.com/discourse/discourse/commit/956d15d13fd8056cbf60ca64ebbd1edca00d0125

Note that for oneboxes where the image is the actual content (such as instagram/twitter/etc photos), they will be selected.

As for the youtube video, I fixed that yesterday.

https://github.com/discourse/discourse/commit/0c6f30d92a4090aa7447e2e579a17a180e49ce17

5 Mi Piace

Ah great, thanks for confirmation.

That’s odd, build was more recent, but some still seem to be being overlooked.

Yeah, that’s partly why I ended up implementing a thumbnail picker for the situations where the automated choice wasn’t optimal. I may still want to modify that behaviour, but I will try to do so in the plugin.

Thanks for your time David!

2 Mi Piace

OK, I’ve worked it out. After a somewhat fruitless byebug session I could not work out why older YT posts were not getting thumbnails.

Then is dawned on me. It’s because of this:

So I suggest that actually it might be necessary to rebake after setting this to a rather larger number (365?).

I think I’m right in saying that if something is not uploaded locally, it won’t have a thumbnail created? …

4 Mi Piace

:+1: correct, this only works for local uploads… we may need to rethink that “max days old” setting :thinking:

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I have a plan, will try and get it implemented this week. One question - do you need the values to be dynamic?

i.e. Will the resolutions be defined at boot? Or at runtime (e.g. via site settings)?

The former is easier… but the latter might be possible as well :thinking:

2 Mi Piace

Thanks for taking a look.

I just need a fixed way, exactly like the theme component.

A site setting would be nice though.

I will add for full disclosure: id like to migrate away from the plugin so parity with theme component solution would be more than enough.

2 Mi Piace

@merefield here you go:

Hopefully the commit message explains how it works, but let me know if you have any questions

7 Mi Piace

Excellent. Just added it to TLP and looks like it’s working! Thanks for your help!

4 Mi Piace

4 posts were split to a new topic: Getting thumbnails from json endpoints

Can we make it work for images from remote server as well? For example, images from Blogger, Picasa, or Amazon S3?

Because Discourse supports hosting on Amazon S3 for big and large image site, now if everything needs to be hosted on the local server directly then this design methodology seems to be a drawback.

With this update, it’s not an easy fix for my site since we’re using other server to host the images. Now it’s too difficult to move to an affiliated server with many posts, while it’s too big for hosting on local sever.

This is only designed to work on Discourse ‘uploads’. Those can be on S3, or some other service, if you use

We recommend using the download_remote_images site setting to automatically download images which are hotlinked from other sites.

4 Mi Piace

Hi David, anything special one needs to do to ensure Pro icons can be used in a TC?

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Nothing special, no. It should work just the same as using pro icons elsewhere in Discourse. I guess you are using this plugin to enable pro icons?

If it doesn’t work let me know and I’ll take a look :eyes:

2 Mi Piace

Yep we are. We’ll have another dig. Thanks for response late your eve!

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