观察者内部 Vue 类组件装饰器的访问方法

Question

本质上，我在 Github 上有与此和此问题相同的问题，不幸的是，它们在得到答复之前都已关闭：/

我将 Vue 与 Typscript 和 Vue 类组件一起使用。我需要做的是从 @Component 装饰器内的观察者内部访问我的（Vue-）类的方法。我知道可以使用 访问组件的数据this.$data，但是方法呢？

我的代码可以在运行时运行，但会在 vscode 中产生编译时错误和错误（“属性‘clearInfo’在类型‘Vue’上不存在。”)；

@Component({
  watch: {
    firstMesh(newMesh) {
      if (newMesh === undefined) this.clearInfo(1);   // this produces the errors
      else this.showMeshInfo(newMesh, 1);
    },
    secondMesh(newMesh) {
      if (newMesh === undefined) this.clearInfo(2);
      else this.showMeshInfo(newMesh, 2);
    },
  },
})


export default class Info extends Vue {
  clearInfo(whichMesh : number) {
...
  }

  showMeshInfo(mesh : any, index : number) {
    ....
  }


}

Answer 1

您有两个选择：

1. 在类本身中定义手表

// first you need to install vue-property-decorators with npm i -S vue-property-decorator
// This library has a lot of useful decorators. You can read more about it here: https://github.com/kaorun343/vue-property-decorator

import { Vue, Component, Watch } from 'vue-property-decorator'


@Component
export default class Info extends Vue {
  @Watch('firstMesh')
  public watchFirstMesh(newValue) {
     // ... do whatever you need to do with the newValue here
  }

  @Watch('secondMesh')
  public watchSecondMesh(newValue) {
     // ... do whatever you need to do with the newValue here
  }
}

2. 在 @Component 的选项部分定义监视和方法

@Component({
  watch: {
    firstMesh(newMesh) {
      if (newMesh === undefined) this.clearInfo(1);   // this produces the errors
      else this.showMeshInfo(newMesh, 1);
    },
    secondMesh(newMesh) {
      if (newMesh === undefined) this.clearInfo(2);
      else this.showMeshInfo(newMesh, 2);
    },
  },
  methods: {
   clearInfo(whichMesh : number) {
     ...
   },
   showMeshInfo(mesh : any, index : number) {
     ....
   }   
  }
})
export default class Info extends Vue {
  // Now you need to tell to typescript that there will be a method inside this class called clearInfo and showMeshInfo
  public clearInfo!: (wichMesh: number) => void;
  public showMeshInfo!: (mesh: any, index: number) => void;
}

解释

1. 可以在我留下的链接上阅读说明

2. 由于您在装饰器中定义选项，因此@Component({...})该选项将在实例化类的上下文中可用。Typescript 不会知道到底有什么可用（我们希望它那么聪明）。你必须告诉它，这就是我们拥有这个public clearInfo!: (wichMesh: number) => void;角色的原因。如果你不知道这个语法意味着什么，我会用简短的​​话解释并在最后留下一个链接：

public clearInfo!: (wichMesh: number) => void;

the ! part is called the non-null assertion operator. It is a way to tell the compiler "this expression cannot be null or undefined here, so don't complain about the possibility of it being null or undefined."

The (wichMesh: number) => void; is the function signature. Basically it says: this will be a function that receives as the first argument a number (whichMesh) and returns void (=> void)

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