用之前 Unity 經驗在寫 cocos 元件的時候遇到一堆警告，搞了老半天才發現是怎麼回事
當有繼承 Component 的類別互相引用對方，其類別屬性是對方類別且宣告成 @property()，可能就會發生以下錯誤
1
2
3
|
[Scene] Found possible circular reference in "pack:///mods/fs/0/assets/MyComponentB.js", happened when use "MyComponentA" imported from "./MyComponentA" Error
[Scene] You are explicitly specifying `undefined` type to cc property "_a" of cc class "MyComponentB".
[Scene] Please specifiy a default value for "MyComponentB._a" property at its declaration:
|
範例
1
2
3
4
5
6
7
8
9
10
11
|
// MyComponentA.ts
import { Component, _decorator } from 'cc';
import { MyComponentB } from './MyComponentB';
const { ccclass, property } = _decorator;
@ccclass('MyComponentA')
export class MyComponentA extends Component {
@property({ type: MyComponentB })
private _b!: MyComponentB;
}
|
1
2
3
4
5
6
7
8
9
10
11
|
// MyComponentB.ts
import { Component, _decorator } from 'cc';
import { MyComponentA } from './MyComponentA';
const { ccclass, property } = _decorator;
@ccclass('MyComponentB')
export class MyComponentB extends Component {
@property({ type: MyComponentA })
private _a!: MyComponentA;
}
|
解法
將其中一個類別另外寫一個 interface，@property 的型別改成 Node，再用 Node.getComponent(className: string) 的方式去取得對方元件即可
在 MyComponentB.ts 加入
1
|
export interface IMyComponentB extends MyComponentB { }
|
MyComponentA.ts 修改為
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
|
import { Component, Node, _decorator } from 'cc';
import { IMyComponentB } from './MyComponentB';
const { ccclass, property } = _decorator;
@ccclass('MyComponentA')
export class MyComponentA extends Component {
@property({ type: Node })
private _bNode!: Node;
private _b: IMyComponentB | null = null;
get b(): IMyComponentB {
if (this._b == null) { this._b = this._bNode.getComponent('MyComponentB') as IMyComponentB }
return this._b;
}
}
|
Reference