El cascade echo failed; El cascader does not echo

— Mine is provincial and municipal linkage , It is normal to choose , The resulting binding value is an array [‘ anhui ’,‘ huangshan ’], That's all right. ;
But when checking the details , Anaphylaxis [‘ anhui ’,‘ huangshan ’], The drop-down box does not display the echo value .

— reason ： although data The initialization declaration variable in is an array , But when assigning values, it must be declared as an array again [ ], And then assign a value . Or just insert values directly into the array .

<el-cascader v-model="shengshi" :options="areaOptions2" placeholder=" Provinces " ></el-cascader>

export default {
    
  data () {
    
    return {
    
      shengshi: [],
    }
  },
  methods: {
    
    getInfo () {
    
      if (res.data.province && res.data.city) {
    
        // el-cascader  The echo   Don't define an empty array first   Then the subscript is assigned   Or just stuff the values into the array 
        
        //  Direct assignment does not work 
        // this.shengshi[0] = res.data.province
        // this.shengshi[1] = res.data.city

		//  First declare an array   Reassignment is also possible 
        // this.shengshi = []
        // this.shengshi[0] = res.data.province
        // this.shengshi[1] = res.data.city
		
		//  You can also insert values directly into the array 
        this.shengshi = [res.data.province, res.data.city]
      } else {
    
        this.shengshi = []
      }
    }
  },
}