Validation

Validation is a Core capability. UI skins display errors and map user interactions, but validation rules are part of the runtime protocol.

Field rules

{
  id: 'email',
  type: 'input',
  label: 'Email',
  rules: [
    { required: true, message: 'Email is required' },
    { type: 'email', message: 'Invalid email' }
  ]
}

Dynamic required

{
  id: 'rejectReason',
  type: 'textarea',
  requiredWhen: 'action === "reject"'
}

Named validators

FormXEngine.registerValidator('uniqueName', async ({ value }) => {
  const result = await api.checkName(value)
  return result.available || 'Name already exists'
})

Submit

const valid = await formRef.value?.validate()
if (!valid) return

const values = formRef.value?.getSubmitValues()

Advice

• Put required and format rules on fields.
• Use named validators for reusable business checks.
• Skip hidden or disabled fields unless the business requires otherwise.
• Run expensive async validation on blur or submit.