Passing data between child components

问题

I am struggling for this to work. I need to access the selected value in the ChooseLangComponent from the FormComponent. Is there any direct way to do this or we have to pass it from the parent component (act like middle man)? I already tried with $emit on ChooseLangComponent and v-on:.. on FormComponent but didn't work.

ChooseLangComponent:

<template lang="html">
    <div class="choose-lang">
        <select v-model="selected">
            <option v-for="lang in langs" v-bind:value="lang.value">{{lang.text}}</option>
        </select>
    </div>
</template>

<script>
    export default {
        data() {
            return {
                selected: 'en',
                langs: [
                    { text: 'English', value: 'en' },
                    { text: 'German', value: 'ge' },
                ]
            }
        }
    }
</script>

FormComponent:

<template lang="html">
    <div class="form-name">
        <div class="inputs">
            <input type="text" v-model="nameText" v-on:keyup.enter="send_name">
        </div>
    </div>
</template>

export default {
    data() {
        return {
            nameText: '',
        }
    },
    methods: {
        send_name() {
              // I need the selected language here
        }
    }
}

The parent component:

<div id="app">
    <choose-lang></choose-lang>
    ...
    <form-comp></form-comp>
</div>

...
Vue.component('choose-lang', require('./components/ChooseLangComponent.vue'));
Vue.component('form-comp', require('./components/FormComponent.vue'));

const app = new Vue({
el: '#app',
data: {
    ...
});

回答1:

Okay there are 2 easy ways and one more which involves the Vuex, if your app is large scale.

First way is creating the Event Bus - idea is emitting Events in one hub and then catching them where It's needed.

const Bus = new Vue({})

Vue.component('lang', {
       template: '#lang-tmp', 
       data() {
            return {
                selected: 'en',
                langs: [
                    { text: 'English', value: 'en' },
                    { text: 'German', value: 'ge' },
                ]
            }
        },
        created() {
          this.changeLang()
        },
        methods: {
          changeLang() {
            Bus.$emit('langChanged', this.selected)
          }
        }
})

Vue.component('frm', {
  template: '#frm-tmp',
  data() {
    return {
      selectedItem: 'en'
    }
  },
  created() {
    Bus.$on('langChanged', (selected) => {
      this.selectedItem = selected
    })
  }
})

const app = new Vue({

  el: '#app'

})

http://jsbin.com/siyipuboki/edit?html,js,output

Second way is creating sort of store - plain object that would hold the state of selected item

const store = {
  data: {
    selected: null
  }
}

Vue.component('lang', {
       template: '#lang-tmp', 
       data() {
            return {
                selected: 'en',
                langs: [
                    { text: 'English', value: 'en' },
                    { text: 'German', value: 'ge' },
                ]
            }
        },
        created() {
          this.changeLang()
        },
        methods: {
          changeLang() {
            store.data.selected = this.selected
          }
        }
})

Vue.component('frm', {
  template: '#frm-tmp',
  data() {
    return {
      storeSelected: store.data
    }
  }
})

const app = new Vue({

  el: '#app'

})

http://jsbin.com/qagahabile/edit?html,js,output

Also please check this VueJS access child component's data from parent

来源：https://stackoverflow.com/questions/43155274/passing-data-between-child-components