未调用设置方法

Question

我用 vue ui（typescript、babel、linter）创建了一个入门项目。一切正常，但我不太明白如何使 Composition API 的 setup 方法起作用。它根本没有被调用（日志输出为空）这就是我卡住的地方。

vue: 3.0.0-rc.10

vue-cli: 4.5.4

<script lang="ts">
 import { Options, Vue } from 'vue-class-component'
 import HelloWorld from './components/HelloWorld.vue'

 @Options({
   components: {
     HelloWorld
   },
   setup () {
     console.log('SETUP HERE')
   }
 })
 export default class App extends Vue {
   setup () {
     console.log('SETUP THERE')
   }
 }
 </script>

Answer 1

您应该从 vue-class-component 导入 setup 然后像这样使用它：

<template>
  <div>Count: {{ counter.count }}</div>
  <button @click="counter.increment()">+</button>
</template>

<script lang="ts">
import { ref, reactive, onMounted } from 'vue'
import { Vue, setup } from 'vue-class-component'

function useCounter () {
  const count = ref(0)

  function increment () {
    count.value++
  }

  onMounted(() => {
    console.log('onMounted')
  })

  return {
    count,
    increment
  }
}

export default class Counter extends Vue {
  counter = setup(() => useCounter())
}
</script>

有关详细信息，请查看此 issue

Answer 2

我遇到了同样的问题，是扩展子组件导致的。如果扩展组件，则永远不会调用 组合 API（设置方法）。 选项 API 生命周期挂钩在两个组件中被调用。

// child.js

<script>
import { onMounted } from "vue";

export default {
  name: "ChildComponent",
  setup() {
    console.log('Child - setup()');
    onMounted(() => {
      console.log('Child - mounted (composition API)');
    })
  },
  mounted() {
    console.log('Child - mounted (option API)');
  }
}
</script>

// parent.js

<script>
import ChildComponent from "./child.js";
import { onMounted } from "vue";

export default {
  name: "ParentComponent",
  extends: ChildComponent,
  setup() {
    console.log('Parent - setup()');
    onMounted(() => {
      console.log('Parent - mounted (composition API)');
    })
  },
  mounted() {
    console.log('Parent - mounted (option API)');
  }
}
</script>

输出

Parent - setup()
Parent - mounted (composition API)
Child - mounted (option API)
Parent - mounted (option API)

未调用设置方法

Setup method is not being called

typescript

vue.js

vuejs3

vue-composition-api

vue-script-setup