如何在Vuejs中将项目推入数据对象的数组中? Vue似乎没有在看.push()方法 [英] How do I push items into an array in the data object in Vuejs? Vue seems not to be watching the .push() method
问题描述
我正在尝试将对象添加到在Vue实例数据对象中声明的数组中.我可以在州的购买对象中设置值,但是当我将数据推入订单队列数组时,不会填充空数组.该函数正在被触发,但数组未更新.
I am attempting to add objects into an array I declared in Vue instance data object. I can set the values in the state's purchase object, but when I push data into the orders queue array, the empty array is not populated. The function is being triggered, but the array does not update.
这是我的表格:
<form
v-on:submit.prevent="queuePurchase"
class="form-inline row"
id="order-creation-form"
method="POST"
>
@csrf
<autocomplete-field
sizing="col-xs-12 col-sm-3 col-md-3"
name="customer"
label="Customer"
:data="{{ json_encode($customers) }}"
v-on:setcustomer="setCustomer($event)"
></autocomplete-field>
<div class="col-xs-12 col-sm-3 col-md3 form-group d-flex flex-column align-items-start">
<label for="phone">Product</label>
<select
v-model="purchase.product"
class="form-control w-100"
name="product"
aria-describedby="productHelpBlock"
required
>
@foreach ($products as $product)
<option :value="{{ json_encode($product) }}">
{{ $product->name }}
</option>
@endforeach
</select>
<small id="productHelpBlock" class="form-text text-muted">
Select a product
</small>
</div>
<div class="col-xs-12 col-sm-3 col-md-3 form-group d-flex flex-column align-items-start">
<label for="phone">Quantity</label>
<input
v-model="purchase.quantity"
type="number"
min="1"
name="product"
class="form-control w-100"
aria-describedby="productHelpBlock"
required
>
<small id="productHelpBlock" class="form-text text-muted">
Product quantity
</small>
</div>
<div class="form-group">
<button type="submit" class="btn btn-success icon-button d-flex">
<i class="material-icons">add</i>
<span> Q U E U E</span>
</button>
</div>
</form>
这是我的javascript:
And here is my javascript:
require("./bootstrap");
window.Vue = require("vue");
Vue.component("queue-table", require('./components/QueueTable.vue'));
Vue.component("autocomplete-field", require('./components/AutocompleteField.vue'));
const purchaseApp = new Vue({
el: "#purchase-app",
data() {
return {
queue: [],
purchase: {
product: null,
customer: null,
quantity: null
}
}
},
methods: {
setCustomer: function(customerObj) {
this.purchase.customer = customerObj;
},
queuePurchase: function() {
this.queue.push( this.purchase );
}
}
});
有人可以解释一下&为什么会发生?
Could someone please explain what & why it is happening?
推荐答案
push()
方法应将purchase
对象添加到queue
数组,但是正如@ FK82在其注释中指出的那样,push()
是将多个引用添加到同一purchase
对象.这意味着,如果通过增加quantity
来更改对象,则每个purchase
的quantity
属性都将被更新.
The push()
method ought to add purchase
objects to the queue
array, but as @FK82 pointed out in his comment, push()
is adding multiple references to the same purchase
object. This means that if you change the object by increasing the quantity
, every purchase
's quantity
property will be updated.
您可以在这里尝试一下:
You can give that a try here:
const exampleComponent = Vue.component("example-component", {
name: "exampleComponent",
template: "#example-component",
data() {
return {
queue: [],
purchase: {
product: null,
customer: null,
quantity: null
}
};
},
methods: {
queuePurchase() {
this.queue.push( this.purchase );
}
}
});
const page = new Vue({
name: "page",
el: ".page",
components: {
"example-component": exampleComponent
}
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.2.4/vue.min.js"></script>
<template id="example-component">
<div>
<p>The Queue has {{ this.queue.length }} items.</p>
<input
v-model="purchase.quantity"
type="number"
min="1"
name="product"
placeholder="Quantity"
>
<button @click="queuePurchase">
Add to Queue
</button>
<pre>{{ JSON.stringify(this.queue, null, 2) }}</pre>
</div>
</template>
<div class="page">
<example-component></example-component>
</div>
而不是push()
引用相同的purchase
对象,请尝试使用Object.assign({}, this.purchase)
或使用传播运算符创建浅表副本.这是一个使用传播运算符,然后将副本push()
拷贝到queue
上的示例:
Instead of push()
ing a reference to the same purchase
object, try creating a shallow copy with Object.assign({}, this.purchase)
or by using the spread operator. Here's an example that uses the spread operator and then push()
es the copy onto the queue
:
const exampleComponent = Vue.component("example-component", {
name: "exampleComponent",
template: "#example-component",
data() {
return {
queue: [],
purchase: {
product: null,
customer: null,
quantity: null
}
};
},
methods: {
queuePurchase() {
this.queue.push({...this.purchase});
}
}
});
const page = new Vue({
name: "page",
el: ".page",
components: {
"example-component": exampleComponent
}
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.2.4/vue.min.js"></script>
<template id="example-component">
<div>
<p>The Queue has {{ this.queue.length }} items.</p>
<input
v-model="purchase.quantity"
type="number"
min="1"
name="product"
placeholder="Quantity"
>
<button @click="queuePurchase">
Add to Queue
</button>
<pre>{{ JSON.stringify(this.queue, null, 2) }}</pre>
</div>
</template>
<div class="page">
<example-component></example-component>
</div>
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