sometimes, we want to control two-way binding of v-model with bind the value (false or true) to a dynamic property on the Vue instance.
related issue: kazupon/vue-validator#149

use-cases

form field validation

case1: vue-validator

<validator name="validation1"> <input type="text" :sync="$validation1.username.valid" v-model="user.name" v-validate:username="{ minlength: { rule: 32 } }"> </validator>

case2: user custom validation

<input type="text" :sync="valid" v-model="user.name" @input="onInputValidator">

new Vue({ ... data: { user: { name: '' }, valid: false }, methods: { onInputValidator: function (e) { this.valid = e.target.value.length > 32 } } })

spec

• if sync attribute value is true, two-way binding of v-model become enable. data is updated when occured user input events,
• if sync attribute value is false, two-way binding of v-model become disable. data is not updated when occured user input events,