Modules

Everything Vueform does beyond its data layer — Validation, Conditions, HTTP, Dates, Locales, theming — is a Module, an implementation the core looks up by key on the Vueform Instance instead of importing directly. The core only defines the interface each key must satisfy, so whatever is registered under a key is what runs. That makes Modules dependency injection at the framework level, and the lever for two things — bundle size, because unused Modules stay out of the build, and control, because any built-in behavior can be replaced without touching the rest.

Registering Modules

The Full Bundle registers every built-in Module, so there is nothing to do there. The bare @vueform/ui entry in Modular Setup registers none, and you pass them under the modules config option yourself:

import { createVueform } from '@vueform/ui'
import { model, validation, conditions } from '@vueform/ui/modules'

createVueform({
  modules: { model, validation, conditions },
})

The rest of a Modular Setup — components, rules, adapters, and what each part costs — is covered in Code-Splitting.

modules merges per key over the entry's set, so on the Full Bundle passing one key replaces only that Module and keeps every other built-in — the mechanism Swapping a Module builds on.

Each Module reads its options from a $-prefixed config key named after it — $http, $conditions, $security, and so on — listed in Configuration. A non-empty $<name> object in your config without a registered <name> Module warns in development, since the options read as if they were in effect.

The Built-in Modules

Most Modules are documented where their feature lives, so the table links each one to its home:

Module	Provides	Without it
model	The form data layer	Required — see leaving a Module out.
validation	Rules and validators	Everything counts as valid — warns once in dev when an element has rules.
conditions	Conditional availability and conditional props	Every Condition counts as met.
expression	{...} templates and Expression Conditions	Strings pass through as literal text — warns once in dev when a feature needs an engine.
autosave	Remote Autosave and local Drafts	The autosave and draft props have no effect (warns once in dev), and the form's Autosave and Draft methods no-op.
http	Network requests	Every request rejects with a "not registered" error.
date	Date parsing and comparison	useDate(), date Conditions, date rules, and date Expression functions throw.
i18n	Framework strings and localization	Built-in strings show their raw tags, Locale Maps fall back to their first entry, and switching the Locale warns in dev.
theme	Token CSS generation, injection, and dark mode	No Token CSS is generated or injected — a tokens prop warns once in dev.
router	Browser-history sync for multi-page forms	Navigation doesn't touch the URL — warns once in dev when history tracking is enabled.
security	HTML/component gating, sanitization, origin policy, ciphers	Nothing is enforced — see The Security Module.

Leaving a Module Out

model is the one Module Vueform can't run without, since every other Module builds on the data layer. The Bare Entry's createVueform doesn't type-check a config without modules.model and throws at runtime.

Every other Module is optional, and a missing one never breaks the code. Consumers read an inert stand-in in its place, so the outcome is one of two kinds, per the table's last column:

• Most degrade to "the feature isn't there" — Conditions are met, everything is valid, strings stay literal. Where a config or prop shows clear intent — rules set, a tokens prop passed, a locale switch, history tracking turned on — development warns once.
• http and date have no sensible fallback, so they fail at the point of use. An http request rejects — getting the client never throws, so forms that never hit the network keep working — and date throws as soon as a date is needed.

security is the one exception where configuration changes the outcome, because a policy configured without the Module fails closed in production — see The Security Module.

Replacing a Module's engine, swapping one out, or writing your own is covered in In-Depth Modules.