Modules

Lettern has no separate "core admin". Every screen you use, from the content lists and the entry editor to users, settings and the Dashboard, comes from a module: a package inside letterncms/cms, built exactly like a plugin.

A module registers its abilities, permissions, settings, sidebar items and screens through the same public API you use, and nothing else knows it by name. So you can switch off the ones a site doesn't need, and read any of them to learn how to build your own.

#The modules

The required modules are what Lettern needs to keep working: without them there is no admin, and nobody could edit content, secure their account, change a setting or switch a module back on. Everything else is yours to remove. A site with only the required modules and no plugins is a complete, very small CMS.

#Switch a module off

Modules are part of Lettern, not plugins: the ones that can be off are under Plugins → Built In, each with its switch. Or switch one off with php cms plugin disable letterncms/audit, the packages/disable ability (and back on with packages/enable), or in config/plugins.yaml:

enabled:          # plugins that run
  - letterncms/forms
  - letterncms/seo
disabled:         # modules that don't
  - letterncms/audit
  - letterncms/collaboration

Modules are on unless they're listed under disabled; plugins are on when they're listed under enabled.

A module others need can't be switched off before them: letterncms/collections needs letterncms/content, and letterncms/blocks stays on while Site, or a plugin that builds on it, is on. Data is kept, so when you switch a module back on, its items return to the places admins gave them.

#Configure a module

A module's options are a settings namespace like any plugin's, listed in the settings sidebar:

The content module has no settings. Entries per page (50), the autosave delay (1.2 seconds) and the revisions kept per entry (100) are fixed; a plugin can change the revisions kept with the revisions.keep filter.

Values a screen needs reach every admin user through the manifest, under config.<namespace> (useConfig('license') in @letterncms/sdk); the settings themselves stay behind settings.manage.

#Who registered what

While a package registers and boots, it's the current scope, so the abilities and settings it adds record it as their owner (package in abilities/list and settings/list). That's how a plugin's row in Plugins knows which settings to open.

#Build one

A module is a plugin that ships with Lettern: the same composer.json (type: cms-plugin), the same provider (extends Cms\Packages\Plugin), the same admin module. Only three things differ:

• It lives in modules/ of letterncms/cms.
• "required": true in extra.cms marks the ones that may not be switched off.
• It doesn't have to bring a Dashboard widget, as every plugin must. Most do anyway.

If you know how to write a plugin, you know how to write a module. Read modules/audit (a provider, one ability, one screen, one setting) next to Your first plugin.

The admin module provides almost no screens of its own: it's what the others draw in. It only talks to them through the manifest, the SDK and the UI kit, so each can change without the rest.