[英]Angular 6 property binding not working correctly with multi-level object
I have a new app that I am making as a pet project that one of my components is behaving wrong. 我有一个正在做的宠物项目新应用程序,说明我的组件之一出了问题。
I have a complex object that stores the information for D&D monsters. 我有一个复杂的对象,用于存储D&D怪物的信息。 The component is for a option quantity changer with plus and minus buttons the increment and decrement the quantities.
该组件用于带有加号和减号按钮的选项数量更改器,用于增加和减少数量。
When I use it for a tier 1 child (ie. monster.strength) it works correctly and will increment up to the maximum quantity, and down to the base value (but not below base) When I use it for a tier 2 child (ie. monster.speed.base) it will increment correctly, but it actually changes the basemonster value as well as the selectedmonster which prevents the decrement from working. 当我将其用于第1层孩子(即,monster.strength)时,它将正常工作,并且将递增至最大数量,并降低到基本值(但不低于基本值)。当我将其用于2层孩子时( (例如monster.speed.base),它会正确递增,但实际上它会更改basemonster值以及selectedmonster,从而阻止了递减工作。
Here's the code showing how the objects are added to the document. 这是显示如何将对象添加到文档中的代码。
<option-quantity *ngIf="mod.location === 'base'"
[max]="90"
[step]="5"
[costval]="mod.cost"
[baseval]="baseMonster[mod.type][mod.location]"
[(totalcost)]="selectedMonster.cost"
[(optval)]="selectedMonster[mod.type][mod.location]">
</option-quantity>
And here is the components TS file 这是组件TS文件
import { Component, Input, Output } from '@angular/core';
import { EventEmitter } from '@angular/core';
@Component({
selector: 'option-quantity',
templateUrl: './option-quantity.component.html',
styleUrls: ['./option-quantity.component.css']
})
export class OptionQuantityComponent {
@Output('optvalChange') emitter1: EventEmitter<number> = new EventEmitter<number>();
@Output('totalcostChange') emitter2: EventEmitter<number> = new EventEmitter<number>();
@Input('baseval') set setBaseVal(value) {
this.base = value;
}
@Input('optval') set setOptValue(value) {
this.count = value;
}
@Input('costval') set setCostValue(value) {
this.cost = value;
}
@Input('totalcost') set setTotalCostValue(value) {
this.totalcost = value;
}
@Input('step') set setStepValue(value) {
this.step = value;
}
@Input('max') set setMaxValue(value) {
this.max = value;
}
step = 1;
max = 10;
base = 0;
count = 0;
cost = 0;
totalcost = 0;
increment() {
if (this.count < this.max) {
this.count += this.step;
this.totalcost += this.cost * this.step;
this.emitter1.emit(this.count);
this.emitter2.emit(this.totalcost);
}
}
decrement() {
if (this.count > this.base) {
this.count -= this.step;
this.totalcost -= this.cost * this.step;
this.emitter1.emit(this.count);
this.emitter2.emit(this.totalcost);
}
}
onChange() {
this.emitter2.emit(this.totalcost);
this.emitter1.emit(this.count);
}
}
I have verified the problem lies with the tier 2 child, since i tried moving the stats into a stats child, and the speed to the root. 我已经验证了问题出在第2层子级上,因为我尝试将统计信息移到stats子级中,并且将速度移到了根级。 Which made the stats stop working and the speed work fine.
这使得统计信息停止工作并且速度正常。 I COULD just move the speed to the root of the object, but I'd rather not.
我可以将速度移到对象的根,但是我宁愿不这样做。
The component where the values are used is the create-undead component the baseMonster is created by this function: 使用值的组件是createMondead组件,此函数创建baseMonster:
setBase() {
this.baseMonster = Object.assign({}, this.selectedMonster);
this.currentSize = this.baseMonster.size;
this.previousSize = this.baseMonster.size;
}
The entire project can be viewed in my GitHub repo 可以在我的GitHub存储库中查看整个项目
Updates: I've tried using Object.spread instead of assign, but that didn't make any difference. 更新:我尝试使用Object.spread而不是Assign,但这没有任何区别。 If I use Object.freeze and do a deep freeze on the "baseMonster" object, that object will not change, but then the "selectedMonster" stops having its tier 2 child values update.
如果我使用Object.freeze并对“ baseMonster”对象进行深度冻结,则该对象不会更改,但是“ selectedMonster”将停止更新其第2层子值。
Any help would be greatly appreciated. 任何帮助将不胜感激。
The issue is with the way you are doing your copy: 问题与您的复制方式有关:
this.baseMonster = Object.assign({}, this.selectedMonster);
Object.assign won't do a deep copy of the object, as described here : "If the source value is a reference to an object, it only copies that reference value." Object.assign不会做对象的深层副本,描述在这里 :“如果源值是对对象的引用,它只引用值的副本。”
This answer has a simple approach for that: 这个答案有一个简单的解决方法:
clonedObj = JSON.parse(JSON.stringify(originalObj))
This other answer has a detailed explanation on the topic. 此其他答案对此主题有详细说明。
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