ERROR TypeError: Cannot read property 'split' of null in angular custom pipe

Question

我收到此错误错误类型错误：使用此 angular 管道时无法读取属性 'split' 的空错误，这是代码。

import { Pipe, PipeTransform } from '@angular/core';

@Pipe({
  name: 'fullDate'
})
export class DatePipe implements PipeTransform {

  transform(value:any ) {
    const dateArray = value.split('-');
    const date = dateArray[2].substr(0, 1) === '0' ? dateArray[2].substr(1, 1) : dateArray[2];
    const months = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'];
  
    return `${date} ${months[dateArray[1] - 1]} ${dateArray[0]}`;
  }

}

{{ lorem?.lorem_date | fullDate }}

Answer 1

该错误意味着您正在拆分一个空值，因此您只需添加一个检查即可。

这样试试：

transform(value:any ) {
   if(value){ 
        const dateArray = value.split('-');
        const date = dateArray[2].substr(0, 1) === '0' ? dateArray[2].substr(1, 1) : dateArray[2];
        const months = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'];

        return `${date} ${months[dateArray[1] - 1]} ${dateArray[0]}`;
    }
  }

Answer 2

在管道中添加一个 null 检查：

import { Pipe, PipeTransform } from '@angular/core';

@Pipe({
  name: 'fullDate'
})
export class DatePipe implements PipeTransform {
  transform(value: any) {
    if (value) {
      const dateArray = value.split('-');
      const date = dateArray[2].substr(0, 1) === '0' ? dateArray[2].substr(1, 1) : dateArray[2];
      const months = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'];

      return `${date} ${months[dateArray[1] - 1]} ${dateArray[0]}`;
    }
    return value;
  }
}

或

将内容放在 *ngIf:

<p *ngIf="lorem">{{ lorem.lorem_date | fullDate }}</p>

Answer 3

您的代码中基本上发生的是当它是运行时第一次值变量没有分配任何值。因为因为它 return 和错误说 Cannot read property 'split' of null 验证管道内的值以获得值就可以了。请在下面找到示例代码：

 

   import { Pipe, PipeTransform } from '@angular/core';

    @Pipe({
      name: 'fullDate'
    })
    export class DatePipe implements PipeTransform {

      transform(value:any ) {
        if(value){
        const dateArray = value.split('-');
        const date = dateArray[2].substr(0, 1) === '0' ? dateArray[2].substr(1, 1) : dateArray[2];
        const months = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'];
      
        return `${date} ${months[dateArray[1] - 1]} ${dateArray[0]}`;
      }


    }

ERROR TypeError: Cannot read property 'split' of null in angular custom pipe

ERROR TypeError: Cannot read property 'split' of null in angular custom pipe

pipes-filters

angular-pipe

angular

或