Как устранить ошибку vue js и firebase?

Question

[Константин]

[Vue warn]: Property or method "selected" is not defined on the instance but referenced during render. Make sure that this property is reactive, either in the data option, or for class-based components, by initializing the property. See: https://vuejs.org/v2/guide/reactivity.html#Declaring-Reactive-Properties.

found in

---> <Account> at src/components/User/Account.vue
       <VContent>
         <VApp>
           <App> at src/App.vue
             <Root>

Comments

[Александр]

Account.vue в студию
Желательно в теле вопроса
Ошибка в скрипте. Тебе пишут: "selected" is not defined

[Константин]

Александр,

<template>
    <v-container>

      


        <v-navigation-drawer
        absolute
        permanent
        left
      >
        <template v-slot:prepend>
          <v-list-item two-line>
            <v-list-item-avatar>
              <img src="https://randomuser.me/api/portraits/women/81.jpg">
            </v-list-item-avatar>
  
            <v-list-item-content>
              <v-list-item-title>Jane Smith</v-list-item-title>
              <v-list-item-subtitle>Logged In</v-list-item-subtitle>
            </v-list-item-content>
          </v-list-item>
        </template>
  {{dataauthorisation}}
                <!--<button class="btn btn-default" @click="onSubmit" :style="styling" >Click me</button>-->
                <v-btn color="#42cead" dark
                @click="onSubmit"
                :style="styling"
                >Выход</v-btn>
        <v-divider></v-divider>
  
        <v-list dense>
          <v-list-item
            v-for="item in items"
            :key="item.title"
        :to="item.url"
        
          >
            <v-list-item-icon>
              <v-icon>{{ item.icon }}</v-icon>
            </v-list-item-icon>
  
            <v-list-item-content>
              <v-list-item-title>{{ item.title }}</v-list-item-title>
            </v-list-item-content>
          </v-list-item>
        </v-list>
      </v-navigation-drawer>



     <v-card
    class="mx-auto"
    max-width="800"
    tile
  >
    <v-list-item>
      <v-list-item-content>
        <v-list-item-title><h1>Адресная книга (список баз)</h1></v-list-item-title>
      </v-list-item-content>
    </v-list-item>

   <v-data-table
    v-model="selected"
    :headers="headers"
    :items="fio"
    item-key="first_name"
    show-select
    class="elevation-1"
  >
  
  </v-data-table>

  
  <div class="text-center pt-5 pb-5">
        <v-btn color="primary" class="mr-5">Создать базу</v-btn>        <v-btn color="error">Удалить базу</v-btn>
      </div>
     

  </v-card>
                
      
    </v-container>
</template>

<script>
import firebase from 'firebase/app'
export default {
    data() 
  {
        return {
           
              items: [
     
           { title: 'Создать рассылку', icon: 'mail_outline', url: '/create_mailing' },
        { title: 'Адресная книга (базы)', icon: 'book', url: '/book_list'},
        { title: 'Адресная книга (внутр)', icon: 'book', url: '/book' },
      ],

      headers: [
          {
            text: 'ФИО',
            align: 'left',
            sortable: false,
            value: 'first_name',
          },
          { text: 'Email', value: 'email' },
          { text: 'День рождения', value: 'birthday' },
      
        ],
        fio: [
          {
            first_name: 'Konstantin',
            email: '[e-mail]',
            birthday: '21/06/92' ,
           
          },
           {
            first_name: 'Misha',
            email: '[e-mail]',
            birthday: '21/06/92' ,
           
          },
           {
            first_name: 'Yana',
            email: 'girl@mailru' ,
            birthday: '21/06/92' ,
           
          },
          
          
        
         
        
         
          
        ],
      }
    },

    computed: {dataauthorisation: function () {
            var user = firebase.auth().currentUser;
            if (user != null) {
                return user.email;
                //return user.uid;
            }
            else {
                return 'Не авторизованы';
            }


        
    
        },

        styling: function() {
                var user = firebase.auth().currentUser;
                if (user != null) {
                    return {
                        visibility: 'visible'
                    }
                }
                else {
                    return {
                        visibility: 'hidden'
                    }
                }
          },
    },
        methods: {
          onSubmit () {
            firebase.auth().signOut().then(function() {
              alert("Вы вышли из аккаунта");
            }).catch(function(error) {
              alert("Ошибка выхода");
            });
        }
        }
        
    
}

</script>

[Pavel Shvedov]

Константин, так нету selected в data, он и ругается