Why isn't config for Views plugin module translatable?

Question

I am trying to write up a patch for this module: https://www.drupal.org/project/readmore. There is a patch for it: https://www.drupal.org/project/readmore/issues/3055200 which adds configurable text for the "read more" and "read less" links provided by this field formatter. But the configuration for these new settings are not translatable.

I noticed that the readmore.schema.yml did not include entries for these new fields (although the new configuration options do work). I added this:

readmore_text:
  type: string
  label: 'Read more link text'
readless_text:
  type: string
  label: 'Read less link text'

To the .schema file but it doesn't help.

What is missing to trigger translation of this view to show these new configuration options?

Answer 1

First of all, for translatable strings you need type: label. Then the Views entity field schema

views.field.schema.yml:

views.field.field:
  type: views_field
  label: 'Views entity field handler'
  mapping:
    click_sort_column:
      type: string
      label: 'Column used for click sorting'
    type:
      type: string
      label: 'Formatter'
    settings:
      label: 'Settings'
      type: field.formatter.settings.[%parent.type]

expects a field formatter schema with this structure:

field.formatter.settings.daterange_default:
  type: field.formatter.settings.datetime_default
  label: 'Date range default display format settings'
  mapping:
    separator:
      type: label
      label: 'Separator'
      translation context: 'Date range separator'

This example is extending a base class and so it is also extending the schema. Otherwise you can replace the type reference to the parent formatter with type: mapping. See also Language specific settings for field formatters