升级到 Angular 11 后扩展的 DecimalPipe 出现问题

Question

从 Angular 10 升级到 11 并遇到了我们在 DecimalPipe 上的扩展的问题。

管道代码：

 export class CustomNumberFormatPipe extends DecimalPipe implements PipeTransform {

 transform(value: string): string | null {
    if (!value) {
        return null;
    }
    value = value.toString().replace(/,/g, '');
    return super.transform(value);
}

和错误：

 Property 'transform' in type 'CustomNumberFormatPipe' is not assignable to the same property in base type 'DecimalPipe'.
 Type '(value: string) => string' is not assignable to type '{ (value: string | number, 
 digitsInfo?: string, locale?: string): string; (value: null, digitsInfo?: string, locale?: 
 string): null; (value: string | number, digitsInfo?: string, locale?: string): 
 string; }'.
 Type 'string' is not assignable to type 'null'.

以及 DecimalType 定义：

 export declare class DecimalPipe implements PipeTransform {
   private _locale;
   constructor(_locale: string);
   transform(value: number | string, digitsInfo?: string, locale?: string): string | null;
   transform(value: null | undefined, digitsInfo?: string, locale?: string): null;
   transform(value: number | string | null | undefined, digitsInfo?: string, locale?: string): string | null;
   static ɵfac: ɵngcc0.ɵɵFactoryDef<DecimalPipe, never>;
   static ɵpipe: ɵngcc0.ɵɵPipeDefWithMeta<DecimalPipe, "number">;

}

到目前为止，我发现的唯一解决方案是共同修改实际的 DecimalPipe，但我对此并没有信心。提前致谢。

Answer 1

只需转到 DecimalPipe 声明并将其 transform 签名复制到您的管道：

transform(value: number | string, digitsInfo?: string, locale?: string): string | null;
transform(value: null | undefined, digitsInfo?: string, locale?: string): null;
transform(value: number | string | null | undefined, digitsInfo?: string, locale?: string): string | null {
    if (!value) {
        return null;
    }
    value = value.toString().replace(/,/g, '');
    return super.transform(value);
}