Linked Select

A Strapi 5 custom field that renders two cascading dropdowns inside the Content Manager:

1. A parent dropdown listing entries of one content type.
2. A child dropdown listing entries of a related content type, filtered by the selected parent.

It is reusable on any content type — you only configure which content types act as the parent and child when you add the field.

How it works

• The field stores a JSON value: { "parent": "<parentDocumentId>", "child": "<childDocumentId>" }.
• Options are fetched through the plugin's own admin API (using the Document Service), so you do not need to make your content types public.
• The relation between child and parent is auto-detected, so minimal configuration is required.

Setup

The plugin is a local plugin, already enabled in config/plugins.ts:

export default () => ({
  'linked-select': {
    enabled: true,
    resolve: './src/plugins/linked-select',
  },
});

Build the plugin and start Strapi:

cd src/plugins/linked-select && npm install && npm run build
cd ../../.. && npm run develop

Usage

1. In Content-Type Builder, add a field and pick Linked Select from the Custom tab.
2. Configure the field settings:
   • Parent content type — pick from the dropdown (all of your API content types).
   • Child content type — pick from the dropdown. Options are limited to content types already listed as relations on the selected parent.
   • Relation field (optional) — the relation on the child that points to the parent. Auto-detected when empty.
   • Label field (optional) — the field shown as the option label (e.g. name, title). Auto-detected when empty.
3. Save. In the Content Manager, choose a parent; the child dropdown loads the related entries.

Note on the parent content-type dropdown: Strapi's Content-Type Builder only renders static option lists for built-in select settings, so the parent list is fetched once when the admin panel loads (via GET /linked-select/content-types). If it appears empty, refresh the admin panel and reopen the field settings. The child dropdown is a custom input and reloads whenever the parent selection changes.

Prerequisite: the parent content type must declare a relation whose target is the child (e.g. a category with an articles relation to article). The inverse relation on the child is what powers entry filtering in the Content Manager.

Finding a content type UID

A UID follows the pattern api::<singularName>.<singularName>. For a Category collection it is api::category.category.

Admin API (used internally)

Optional query params: labelField, relationField.