[英]Typescript - My property decorator isn't working, why?
我正在嘗試構建自定義裝飾器,例如,一個裝飾器來驗證字符串的最小長度。
function Min(limit: number) {
return function (target: Object, propertyKey: string) {
let value: string;
const getter = function () {
return value;
};
const setter = function (newVal: string) {
if (newVal.length < limit) {
Object.defineProperty(target, 'errors', {
value: `Your password should be bigger than ${limit}`
});
}
else {
value = newVal;
}
};
Object.defineProperty(target, propertyKey, {
get: getter,
set: setter
});
}
}
在課堂上,我這樣稱呼:
export class User {
@Min(8)
password: string;
}
但是,我收到此異常:
tslib_1.__decorate([
^
ReferenceError: Min is not defined
at Object.<anonymous>
我的tsconfig.json:
{
"compilerOptions": {
"module": "commonjs",
"declaration": true,
"removeComments": true,
"emitDecoratorMetadata": true,
"experimentalDecorators": true,
"importHelpers": true,
"target": "es2017",
"sourceMap": true,
"outDir": "./dist",
"baseUrl": "./",
"incremental": true
},
"exclude": [
"node_modules",
"dist"
]
}
PS:我知道有一些用於數據驗證的庫,例如類驗證器,但是,我想為驗證和其他功能創建自定義裝飾器。
我哪里錯了?
看起來您忘記導入裝飾器了。 假設您的結構如下:
- decorator.ts
- index.ts
在decorator.ts
:
export function Min(limit: number) {
// ...
}
在index.ts
:
// Don't forget to import your decorator here
import { Min } from './decorator';
export class User {
@Min(8)
password: string;
}
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