Attaching metadata

An interpreter declares a foldkit-metadata key and attaches entries to the entity or to members. Entity core never reads them.

import { Metadata } from 'foldkit-metadata'

const Labels = Metadata.key<string>('my-admin/labels', {
  merge: labels => [...new Set(labels)],
  summarize: label => label,
})

const CmsPost = Blog.Post.pipe(
  Entity.annotate(Labels.of('Post')),
  Entity.annotateMembers({ title: Labels.of('Title'), author: Labels.of('Byline') }),
)

Labels.get(CmsPost.fields.title.metadata) // ['Title']
Entity.same(CmsPost, Blog.Post) // true: the metadata changed, the entity did not

Annotating again combines with what is there, using the key's own merge.

A schema's own words#

A label or a help text written on a schema (annotate({ title, description })) is read with Words.of(schema), which gives each as an Option. Under Effect 4 a schema with checks resolves to its last check's annotations, which say what the check expects and carry no title, so Schema.String.annotate({ title: 'Name' }).check(Schema.isMinLength(1)) resolved directly has no title. Words.of falls back to the schema's own annotations. A form's labels, Crud's columns and the page Builder's inspector read words through it.

import { Schema } from 'effect'
import { Words } from 'foldkit-entity'

Words.of(Schema.String.annotate({ title: 'Name' }).check(Schema.isMinLength(1))).title
// Option.some('Name')