[Vue warn]: Error in created hook: "TypeError: Cannot set property of undefined"

Question

I am creating a VueJS application. I have a child component, Child.vue to which data is passed from a parent.

Child.vue

export default{

    props:['info'],

    data: function(){
        return{
            timeValue:{
                minutes: '',
                hours: ''
            }
        }
    },
    created: function(){
        
        console.log("Printing inside created of Child ",this.info);
        this.convertMins(this.info[0][2]);
        
    },

    methods:{
        convertMins: (minutes) => {
            console.log("Printing inside convert mins", this);
            if(minutes===0){
                this.timeValue.minutes = 0;
                this.timeValue.hours = 0;
            }
            if(minutes===60){
                this.timeValue.hours = 1;
                this.timeValue.minutes = 0;
            }
            if(minutes>60){
                this.timeValue.hours = Math.floor(minutes/60);
                this.timeValue.minutes = minutes % 60;
            }
        }
    }

}

And my parent component looks like this,

Parent.vue

import Child from './Child.vue';

export default {
data(){
	return{
        info:[ ],

        errors: []
	}
},

created: function(){

  this.accessInformation();
},

methods: {
    
    accessInformation: function(){
    axios.get(localhost:3000/retrieveInfo)
    .then(response =>{
    console.log(response.data.rows[3]);
    this.info.push(response.data.rows[3]);
   })
   .catch(e => {
            this.errors.push(e);
   })
 }
},

components: {								
    'child': Child,
    
  }
}

<template>
 <div>
   <child v-bind:info="info" v-if="info.length > 0"></child>
 </div>
</template>

When I try running the application, I get an error like this,

Why I am getting this error? I am new to VueJS. Can someone please help me out here?

Solution 1

Don't use arrow functions to define methods. See the warning box at https://vuejs.org/v2/guide/instance.html#Data-and-Methods

Solution 2

this in an arrow function refers to the parent context, so here it's referring to the window object, not the Vue object.

Instead of convertMins: (minutes) => {}, use convertMins(minutes) {}.

Comments

[Fathy]

in my case was typo in ".then"