VeeValidate useForm schema reactivity and field re-validation

Answer

If the schema you pass to useForm is a reactive reference (e.g., a ref or reactive object), changing that reference automatically triggers a re‑validation of all currently touched fields. No manual call to validate is required. If the schema is a plain object, VeeValidate does not watch it and you must invoke validation yourself after updating the schema.

Confirmed facts (from VeeValidate v4+ behavior)

• When useForm receives a schema argument that is a reactive ref, VeeValidate sets up a watcher on that ref.
• On each change of the ref, the watcher calls the internal validateAll method, which runs the new schema against every field’s current value and updates error states.
• Field‑level re‑validation respects each field’s immediate mode: with immediate:true the field validates on every input; otherwise it validates on blur or when the schema watcher triggers a re‑run.
• If the schema is a plain object (non‑reactive), no watcher is created; error messages stay stale until you call handleSubmit, validate, or trigger a user interaction that runs validation.

Steps to ensure consistency when the schema changes

1. Declare the schema as a reactive ref:

import { ref } from 'vue'
import { useForm } from 'vee-validate'

const schema = ref(initialSchema)   // <-- reactive
const { handleSubmit, errors } = useForm({ schema })

2. When you need to update the schema, replace the ref’s value (or assign a new reactive object):

// Example: change validation rules based on a select
schema.value = newSchemaBasedOnSelection

3. VeeValidate will automatically re‑validate all touched fields; you can inspect errors in the template to see updated messages.
4. If you are unable to make the schema reactive (e.g., it comes from an external non‑reactive source), wrap it in a ref before passing it to useForm, or call validate manually after updating:

// Manual fallback
schema = newPlainObject
await validate()   // returns a promise with results

Diagnostic detail needed

To confirm whether automatic re‑validation will work for your case, please tell me: Are you passing a reactive ref (e.g., ref or reactive) to the schema option of useForm?

Verification (optional)

In Vue DevTools you can watch the schema ref; when it changes, VeeValidate logs no reactivity warnings and the field error messages update instantly.