为什么我的跟踪阵列在 Ember Octane 中没有更新? [英] Why won't my tracked array update in Ember Octane?

问题描述

我正在试用 Octane，但出于某种原因，如果我在模板中显示一个数组并向其中添加一个新对象，则 UI 不会更新.我做错了什么?

I'm trying out Octane, and for some reason, if I show an array in a template and I add a new object to it, the UI doesn't update. What am I doing wrong?

这是我的模板:

<label for="new-field-name">Field Name</label>
<Input id="new-field-name" @value={{this.newFieldName}} type="text" />
<button {{on "click" this.addField}}>Add field</button>

{{#each this.fields as |field|}}
    <p>{{field.name}}</p>
{{/each}}

和组件:

import Component from '@glimmer/component';
import { tracked } from '@glimmer/tracking';
import { action } from '@ember/object';

export default class ConfigControlsComponent extends Component {
    @tracked fields = []
    @tracked newFieldName = ''

    @action addField() {
        this.fields.push({
            name: this.newFieldName
        })
        console.log(this.fields)
    }
}

console.log 显示了添加了新对象的数组，并且跟踪了 fields 数组，但是当我单击按钮时没有任何变化.>

The console.log shows the array with the new object added to it, and the fields array is tracked, but nothing changes when I click the button.

推荐答案

当您将 tracked 与数组一起使用时，您需要重置"数组，以便 Ember 注意到发生了变化.在将新对象推入数组后尝试执行 this.fields = this.fields.

When you use tracked with arrays, you need to "reset" the array so that Ember notices that there has been a change. Try doing this.fields = this.fields after pushing a new object into the array.

一些短绒将防止自我分配.因此，我们可以从不变性模式中提取，并使用新数组进行设置，如下所示.

some linters will guard against self-assignment. So, instead, we could pull from immutability patterns, and set using a new array, as shown below.

export default class ConfigControlsComponent extends Component {
  @tracked fields = []
  @tracked newFieldName = ''

  @action addField() { 
    // add this line
    this.fields = [...this.fields, {
      name: this.newFieldName
    }]; 
  }
}

如果您尝试将 tracked 与对象而不是数组一起使用，您有两个选择:

If you are trying to use tracked with an object instead of an array, you have two options:

首先，您可以创建一个类来跟踪对象上的所有属性:

First, you could create a class where all the properties on the object are tracked:

import { tracked } from '@glimmer/tracking';

class Address {
  @tracked street;
  @tracked city;
}

class Person {
  address = new Address();

  get fullAddress() {
    let { street, city } = this.address;

    return `${street}, ${city}`;
  }
}

或者，其次，您可以使用与上面的数组示例相同的重置"方法.

Or, second, you could use the same "reset" approach as the array example above.

这篇关于为什么我的跟踪阵列在 Ember Octane 中没有更新?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！