在某些需求流程中，需要根据当前步骤显示不同的form表单数据，根据步骤修改对应的rule会出现blur验证失效的情况，只需要在el-form-item上添加key值即可。

<template>
	<el-form
	  :model="ruleForm"
	  :rules="formRule"
	  ref="ruleForm"
	  class="demo-ruleForm"
	>
		<!-- country info -->
		<div v-if="step == 1">
			<el-form-item label="Country" prop="country" key="country"></el-form-item>
		</div>
		<!-- city info -->
		<div v-if="step == 2">
			<el-form-item label="City" prop="city" key="city"></el-form-item>
		</div>
	</el-form>
</template>
<script>
	watch: {
		step(val) {
			if (val == "1") {
				this.formRule = {
					country: [{
				        required: true,
				        message: "Country cannot be empty",
				        trigger: "blur"
				    }]
				}
			}
			if (val == "2") {
				this.formRule = {
					city: [{
				        required: true,
				        message: "City cannot be empty",
				        trigger: "blur"
				    }]
				}
			}
		}
	}
</script>