Language filter support

[Xpirix]

Fix for #28

[Xpirix]

Hi @Guts

I’m working on your request at #28 and wanted to make sure I’m on the right track.

• Based on the suggested model, the language fields (main and available) are applied directly to a feed. Consequently, all posts originating from each feed will possess the same value for the main language and available languages in the front matter.
• Using the Hugo taxonomies, I’ve extracted the unique values for language from the front matter. Subsequently, I’ve created a language filter (as shown in the screenshot below) to facilitate language selection.

• This filter functions similarly to the existing ones (Subscribers, tags), meaning it will display all posts with the selected language set as the front matter.
• Since these fields are not set for the existing subscribers, I’ve set the default values to en_GB. However, I believe it’s also possible to retrieve the language value from the RSS XML feed.

Could you please provide more details about the expectations for this field? I’m not sure how it will be used.

Regards.