Modificadores de tema: Uma breve introdução

À medida que os temas se tornam mais ambiciosos, temos procurado maneiras de permitir que eles manipulem o comportamento central do servidor. Embora eles nunca recebam o mesmo nível de controle que os plugins, podemos fornecer alguns ganchos predefinidos para os temas manipularem.

Apresentando: modificadores de tema :partying_face:

Eles são especificados usando a chave modifiers no arquivo about.json do seu tema.

Para uma lista 100% atualizada de modificadores, verifique o esquema do banco de dados na parte inferior de theme_modifier_set.rb, mas aqui está um breve resumo do que temos até agora:

  • serialize_topic_excerpts booleano (padrão falso) - sempre inclua trechos ao serializar listas de tópicos

  • csp_extensions array de strings - adicione diretivas ao CSP. Funciona da mesma forma que o antigo método de tema-configuração “extend_content_security_policy”. Mas lembre-se, tags \u003cscript src=\"\"\u003e simples são permitidas automaticamente.

  • svg_icons array de strings - uma lista de ícones que devem ser incluídos no subconjunto de ícones

  • topic thumbnails array de dimensões - solicite resoluções adicionais no conjunto de miniaturas de tópicos. Observe que elas são geradas assincronamente, portanto, você deve usar a imagem original como fallback se o tamanho solicitado não for fornecido. Mais informações disponíveis na mensagem do commit

  • serialize_post_user_badges array de strings - uma lista de nomes de emblemas (correspondentes às entradas na tabela de emblemas) para serializar junto com os dados da postagem. Quando configurado, o sistema inclui os emblemas de usuário especificados com cada postagem para renderização no lado do cliente.

Um tema que faz uso intensivo desses novos ganchos é Topic List Thumbnails - confira o código para ver como funciona.

Modificadores dependentes de configuração

Os modificadores de tema também podem ser configurados para buscar seu valor de uma configuração de tema, permitindo que os operadores do site substituam o comportamento do modificador sem editar o código do tema. Para fazer um modificador depender de uma configuração, use esta sintaxe em seu about.json:

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

Por exemplo, se você tiver uma configuração de tema chamada show_excerpts e quiser que ela controle o modificador serialize_topic_excerpts:

Em settings.yml:

show_excerpts:
  default: false

Em about.json:

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

Quando a configuração show_excerpts for alterada, o valor do modificador será atualizado automaticamente para corresponder. Isso fornece flexibilidade para os operadores do site personalizarem o comportamento do tema por meio da interface de administração.


Este documento é controlado por versão - sugira alterações no github.

35 curtidas

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.

2 curtidas

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

6 curtidas

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!

1 curtida

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 curtidas

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 curtidas

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 curtidas

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 curtidas

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

8 curtidas

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 curtidas

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 curtidas

@merefield here you go:

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

7 curtidas

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

4 curtidas

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 curtidas

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

1 curtida

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 curtidas

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

2 curtidas