vue数据加载不出

Question

new Vue({     el: '.wrap',     data: {         addressList: [],         productList: [],         sendMessage: ''     },     mounted: function() {     this.$nextTick(function() {         this.getAddressList();         this.getProductList();         this.getSendMessage();     });     },     methods: {         getAddressList: function() {             this.$http.get('data/address.json', {}).then(res => {             this.addressList = res.data.result;             });         },         getProductList: function() {             this.$http.get('data/cart.json', {}).then(res => {             this.productList = res.data.result.productList;             });         },         getSendMessage: function() {             var _this = this;             this.addressList.forEach(function(item, index) {                 if (item.isDefault) {                      _this.sendMessage = item.streetName + item.userName + item.postCode;                 }             });         }     }});其他地方都正常运行了this.addressList返回的是json数据streetName userName postCode 都在json里有大概是这样的json在html里 用 {{ sendMessage }} 引用数据了sendMessage并没有改变值是不是不能这么写函数？