Question

如何从 Vue 中的回调访问本地组件变量？

2018-05-13

4286

vue.js callback vuejs2 vue-component axios

我正在尝试使用 api rest 命令设置我的组件变量。我想通过其自己的文件中名为 handleResponse() 的函数来处理所有响应，如下所示。

// api/tools/index.js
function handleResponse (promise, cb, cbError) {
  var cbErrorRun = (cbError && typeof cb === "function") 

  promise.then(function (response) {
    if (!response.error) {
      cb(response)
    }
    else if (cbErrorRun) {
      cbError(response)
    }
  }).catch(function (error) {
    console.log(error)
    if (cbErrorRun) {
      var responseError = {
        "status": 404,
        "error": true,
        "message": error.toString()
      }
      cbError(responseError)
    }
  })
}
export {handleResponse}

在我的组件文件中，我有这个

.... More above....
<script>
import { fetchStock } from '@/api/stock'    

  export default {

    data () {
      return {
        stock: {},
        tabs: [
          {
            title: 'Info',
            id: 'info'
          },
          {
            title: 'Listings',
            id: 'listings'
          },
          {
            title: 'Company',
            id: 'company'
          }
        ],
      }
    },
    validate ({params}) {
      return /^\d+$/.test(params.id)
    },
    created: function() {
      var params = {'id': this.$route.params.stockId}
      //this.$route.params.stockId}
      fetchStock(
        params,
        function(response) { //on successful data retrieval
          this.stock = response.data.payload // payload = {'name': test123}
          console.log(response)
        },
        function(responseError) { //on error
          console.log(responseError)
        }
      )
    }
  }
</script>

当前代码给了我这个错误：“未捕获（在承诺中）TypeError：无法设置 undefinedAc 的属性‘stock’”。我认为发生这种情况是因为我无法再访问传入 fetchStock 函数的回调中的“this”。如何在不更改当前 handleResponse 布局的情况下修复此问题。

Answer 1

你可以试试这个技巧

  created: function() {
      var params = {'id': this.$route.params.stockId}
      //this.$route.params.stockId}
      var self = this;
      fetchStock(
        params,
        function(response) { //on successful data retrieval
          self.stock = response.data.payload // payload = {'name': test123}
          console.log(response)
        },
        function(responseError) { //on error
          console.log(responseError)
        }
      )
    }

Answer 2

您可以使用箭头函数进行回调，因为箭头函数维护并使用其包含范围的 this ：

created: function() {
      var params = {'id': this.$route.params.stockId}
      //this.$route.params.stockId}

      fetchStock(
        params,
        (response) => { //on successful data retrieval
          self.stock = response.data.payload // payload = {'name': test123}
          console.log(response)
        },
        (responseError) => { //on error
          console.log(responseError)
        }
      )
    }

或者您可以在回调之前在方法的开头分配 const vm = this ，就像这样。

vm stands for "View Model"

created: function() {
      var params = {'id': this.$route.params.stockId}
      //this.$route.params.stockId}
      const vm = this;
      fetchStock(
        params,
        function(response) { //on successful data retrieval
          self.stock = response.data.payload // payload = {'name': test123}
          console.log(response)
        },
        function(responseError) { //on error
          console.log(responseError)
        }
      )
    }

I advise using the const as opposed to var in the vm declaration to make it obvious the value of vm is a constant.