How to use external object in Vue's data() function?-CodePudding

So, the stadard way of defining data in Vue component is by using the data function like in the following example:

data()
{
    return {
        a:0
    }
}

My question is, instead of defining the data object after return, can I define the data object somewhere else and just create its instance in data function?

So, for example:

Inside Vue component:

data()
{
    return new DataObject();
}

and then in DataObject.js do:

class DataObject
{
    constructor(a)
    {
        this._a = a;
    }
    get a()
    {
        return this._a;
    }
    set a(a)
    {
        if (a > 0)
        {
            this._a = a;
        }
        else
        {
            this._a = 0;
        }
    }
}

This does not work. I created the following workaround which enables me to do this:

data()
{
    return {
        data: new DataObject();
    }
}

and this works as expected, but I still define the wrapper data object in order to be able to use data object and I have to access the a as this.data.a instead of just this.a.

So, is it possible to implement this on my way, without defining the data nor wrapper data object inside the data function?

So I want to be able to return external data object from the data function.

CodePudding user response：

It's fine to construct the object outside of the data prop. The problem with the OP code is the DataObject's getters. vue will replace those with reactive get/set, deleting the knowledge of the underlying variable.

class SomeClass {
  constructor() {
    this.a = 'A';
    this.b = 'B';
    this.c = 'C';
  }
  // get a() will be overwritten
}

window.onload = () => {
  new Vue({
    el: '#app',
    data: function() {
      return new SomeClass()
    },
  })
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script>
<div id="app">
  <h3>{{a}}</h3>
  <h3>{{b}}</h3>
  <h3>{{c}}</h3>
</div>

CodePudding user response：

you are not providing a name to the object you are trying to create

return new DataObject();

try instantiating the class somewhere in your code first and then return it

let instance = new DataObject();

return instance;