Vue 3 Composition API reuse in multiple components

问题

I have these files

App.vue, Header.vue, search.js and Search.vue

App.vue is normal and just adding different views

Header.vue has an input box

<input type="text" v-model="searchPin" @keyup="searchResults" />
<div>{{searchPin}}</div>

and script:

import useSearch from "@/compositions/search";

export default {
  name: "Header",
  setup() {
    const { searchPin, searchResults } = useSearch();

    return {
      searchPin,
      searchResults
    };
  }
};

search.js has the reusable code

import { ref } from "vue";

export default function useSearch() {
  const searchPin = ref("");

  function searchResults() {
    return searchPin.value;
  }

  return {
    searchPin,
    searchResults
  };
}

Now, this is working well.. once you add something on the input box, it is showing in the div below.

The thing I have not understood is how to use this code to a third component like Search.vue.

I have this, but its not working.

<template>
  <div>
    <h1 class="mt-3">Search</h1>
    <div>{{ searchPin }}</div>
  </div>
</template>

<script>
  import useSearch from "@/compositions/search";

  export default {
    name: "Search",
    setup() {
      const { searchPin, searchResults } = useSearch();

      return {
        searchPin,
        searchResults
      };
    }
  };
</script>

What am I missing? Thanks.

回答1:

The fix for this is very simple

instead of

import { ref } from "vue";

export default function useSearch() {
  const searchPin = ref("");

  function searchResults() {
    return searchPin.value;
  }

  return {
    searchPin,
    searchResults
  };
}

use

import { ref } from "vue";

const searchPin = ref("");

export default function useSearch() {  

  function searchResults() {
    return searchPin.value;
  }

  return {
    searchPin,
    searchResults
  };
}

The problem is that the searchPin is scoped to the function, so every time you call the function, it gets a new ref. This is a desirable effect in some cases, but in your case, you'll need to take it out.

Here is an example that uses both, hope it clears it up.

const {
  defineComponent,
  createApp,
  ref
} = Vue


const searchPin = ref("");

function useSearch() {
    const searchPinLoc = ref("");

  function searchResults() {
    return searchPin.value + "|" + searchPinLoc.value;
  }

  return {
    searchPin,
    searchPinLoc,
    searchResults
  };
}

const HeaderComponent = defineComponent({
  template: document.getElementById("Header").innerHTML,
  setup() {
    return useSearch();
  },
})


const SearchComponent = defineComponent({
  template: document.getElementById("Search").innerHTML,
  setup() {
    return useSearch();
  }
})

createApp({
  el: '#app',
  components: {
    HeaderComponent, SearchComponent
  },
  setup() {}
}).mount('#app')

<script src="https://unpkg.com/vue@3.0.0-rc.9/dist/vue.global.js"></script>
<div id="app">
  <header-component></header-component>
  <search-component></search-component>
</div>

<template id="Header">
  searchPin : <input type="text" v-model="searchPin" @keyup="searchResults" />
  searchPinLoc : <input type="text" v-model="searchPinLoc" @keyup="searchResults" />
  <div>both: {{searchResults()}}</div>
</template>

<template id="Search">
  <div>
    <h1 class="mt-3">Search</h1>
    <div>both: {{searchResults()}}</div>
  </div>
</template>

来源：https://stackoverflow.com/questions/63681970/vue-3-composition-api-reuse-in-multiple-components