How to solve [Vue warn]: props must be strings when using array syntax?

Question

My view is like this :

<div class="col-md-8">
    ...
        <star :value="{{ $data['rating'] }}" :user="{{ $data['user_id']></star>
    ...
</div>

My star component is like this :

<template>
    <span class="rating">
        <template v-for="item in items">
            <label class="radio-inline input-star" :class="{'is-selected': ((value >= item.value) && value != null), 'is-disabled': disabled}">
                <input type="radio" class="input-rating" name="input-rating" v-bind:value="item.value" v-model="value" :disabled="disabled" @click="rate(item.value)">
            </label>
        </template>
    </span>
</template>
<script>
    export default{
        props: [{'value': null,'disabled': Boolean}, 'user'], 
        data(){
            return{
                items: [
                    {value: 5},
                    {value: 4},
                    {value: 3},
                    {value: 2},
                    {value: 1}
                ],
                temp_value: null,
            }
        },
        methods:{
            rate: function (star) {
                var self = this;
                if (!this.disabled) {
                    this.$http.post(window.BaseUrl + '/star', {star: star}).then(function (response) {
                        console.log('submitted');
                    });
                    this.temp_value = star;
                    return this.value = star;
                }
            },
        }
    }
</script>

My css is like this :

span.rating {
  direction: rtl;
  display: inline-block;
}

span.rating .input-star {
  background: url("../img/star.png") 0 -16px;
  padding-left: 0;
  margin-left: 0;
  width: 16px;
  height: 16px;
}

span.rating .input-star:hover, span.rating .input-star:hover ~ .input-star {
  background-position: 0 0;
}

span.rating .is-selected{
   background-position: 0 0;
}

span.rating .is-disabled{
   cursor: default;
}

span.rating .input-star .input-rating {
  display: none;
}

When I click the star, there exist error on the console like this :

[Vue warn]: props must be strings when using array syntax.

[Vue warn]: Property or method "star" is not defined on the instance but referenced during render. Make sure to declare reactive data properties in the data option. (found in at C:\xampp\htdocs\myshop\resources\assets\js\components\Star.vue)

[Vue warn]: Property or method "disabled" is not defined on the instance but referenced during render. Make sure to declare reactive data properties in the data option. (found in at C:\xampp\htdocs\myshop\resources\assets\js\components\Star.vue)

How can I solve it?

props should be an object when you need to validate. And don't use {{ }} on prop bindings. — Mat J

CodinCat CodinCat · Accepted Answer · 2017-03-01T06:45:41

There are several errors in your code.

First, you don't need the braces in props:

<star :value="{{ $data['rating'] }}" :user="{{ $data['user_id'] }}"></star>
         <!-- ^^ syntax error -->

just:

<star :value="$data['rating']" :user="$data['user_id']"></star>

and this can be simplified to:

<star :value="rating" :user="user_id"></star>

Another error is the declaration of props. That's the reason why Vue told you it can't recognize disabled and value.

The simplest way is props: ['value', 'disabled', 'user'],

If you want to add validations, follow the documentation here: https://vuejs.org/v2/guide/components.html#Prop-Validation

Another problem is that you are mutating props directly.

<input ... v-model="value" ...>

The value is a prop. The flow of props is one way down. A component should not mutate its props.

If you want to send the value back to parent, use events. Here is the documentation of events: https://vuejs.org/v2/guide/components.html#Custom-Events

or see my previous answer: Update parent model from child component Vue

How to solve [Vue warn]: props must be strings when using array syntax?

1 Answers