类型“T[keyof T]”上不存在属性“toLowerCase”

问题描述

我正在尝试编写一个带有两个 args（obj 数组和搜索词）的泛型函数，但出现错误 - 属性 'toLowerCase' 在类型 'T[keyof T] 上不存在'

这里是函数：

public initFullscreenModal = ():ng.IPromise<any> => this.ModalService
            .showModal({
                component: 'modalimageFullscreen',bodyClass: 'angular-modal-service-active',bindings: {
                    image: this.image
                },// This method is invoked when `ModalService.closeModals()` is called from within ModalService
                preClose: (modal: IDavis.Modal,result: any) => {
                    // We need this in order to properly close the Bootstrap modal via `.modal('hide')`
                    modal.element.modal('hide');
                }
            })
            .then( (modal: IDavis.Modal): void => {
                // required for Bootstrap Modal
                modal.element.modal('show');
            })
            .catch( (error: any) => {
               console.error('imageController.initModal().ModalService.showModal().ERROR',error);
            });

这里缺少什么？

解决方法

似乎与此问题有关：https://github.com/microsoft/TypeScript/issues/10530

您仍然可以将 obj[value] 拉出到变量中以获得类型推断：

function matchSearchTerm<T>(data: T[],search: string): T[] {
  return data.filter((obj) => {
    const filteredData = (Object.keys(obj) as Array<keyof typeof obj>).some((value) => {
      const val = obj[value];
      return (
        typeof val === "string" && val.toLowerCase().includes(search.toLowerCase())
      );
    });
    return filteredData;
  });
}

,

function matchSearchTerm<T extends Record<string,string>>(data: T[],search: string) {
  return data.filter((obj) => {
    const filteredData = (Object.keys(obj) as Array<keyof T>).some((value) => {
      const checkIt = obj[value]
      type O = typeof checkIt
      return (
        typeof obj[value] === "string" && obj[value].toLowerCase().includes(search.toLowerCase())
      );
    });
    return filteredData;
  });
}

只需为您的 T 通用参数添加额外的约束：T extends Record<string,string>