如何在将服务返回给 angular 客户端之前修改服务中的项目？

Question

从我的数据访问服务返回数据时，我只在修改响应后得到未定义。我的管道出了什么问题？

.pipe(
  map(result => result['dimensions']),
  map(result => result.forEach(element => {
    result.dimensionItems = element.dimensionItems.map(item => {
      item.parentId = result.dimensionId;
      item.dimensionItemId = Math.floor(Math.random() * 1000);
    });
  })),
  tap(result => console.log('Aiiiaiiii: ', result)),
  catchError(this.handleError)
);

Answer 1

forEach return 未定义 [1]，因此您需要将代码更改为：

.pipe(
  map(result => result['dimensions']),
  map(result => {
    result.forEach(element => {
      result.dimensionItems = element.dimensionItems.map(item => {
        item.parentId = result.dimensionId;
        item.dimensionItemId = Math.floor(Math.random() * 1000);
      });
    });
    return result; // You need to return the result after the foreach.
  }),
  tap(result => console.log('Aiiiaiiii: ', result)),
  catchError(this.handleError)
);

正如您从评论中看到的那样，您需要 return 使用 forEach 操作后的结果。

参考资料 [1] - Array.prototype.forEach() - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/forEach

如何在将服务返回给 angular 客户端之前修改服务中的项目？

How do I modify items in a service before returning it back to angular client?

javascript

angular-httpclient