Vue how to use v-model on sync prop in child component

  javascript, vue.js

in parent component, I pass a prop using .sync to achieve 2-way binding, in child components, I simply bind that prop to a v-model, in this way, I hope any change in child component can be propagated to parent through this .sync prop. However, I received the warning:

[Vue warn]: Avoid mutating a prop directly since the value will be overwritten whenever the parent component re-renders. Instead, use a data or computed property based on the prop's value.

Am I doing anything wrong? According to vue document, .sync is designed by 2-way data binding. How should I do this in child components?

Source: Ask Javascript Questions