angular - 属性类型 'slidesPerView' 不兼容

Question

考虑一个带有 NGX-Swiper-Wrapper 插件的 Angular 6 应用程序。
Swiper 插件在 SwiperComponent 模板文件中调用:

<swiper [config]="customConfig">
...
</swiper>

为了保持组件文件的可读性，swiper 配置取自服务:

import { Component, OnInit } from '@angular/core';
import { DataService } from '../../services/data.service';
import { SwiperConfigInterface } from 'ngx-swiper-wrapper';
...
export class SwiperComponent implements OnInit {
  customConfig: SwiperConfigInterface;

  constructor(private dataService: DataService) { }

  ngOnInit() {
    this.customConfig = this.dataService.getCustomConfig();
  }

}

这是服务:

import { Injectable } from '@angular/core';
...
export class DataService {

  constructor() { }

  getCustomConfig() {
    return {
      observer: true,
      direction: 'vertical',
      slidesPerView: 'auto',
      freeMode: true,
      ...
    };
  }

  // Lots of other configs here
  ...

}

错误来了:

error TS2322: Type '{ ... slidesPerView: string; ...' is not assignable to type 'SwiperConfigInterface'. Types of property 'slidesPerView' are incompatible. Type 'string' is not assignable to type 'number | "auto"'.

这个错误可以粗暴的省略，只是将customConfig变量的类型从SwiperConfigInterface改为any。但是有人知道解决这个问题的更好方法吗？

Answer 1

SwiperConfigInterface 的 slidesPerView 属性需要一个 number 类型的值或一个 'auto' 类型的值:

slidesPerView?: number | 'auto',

根据错误消息，Typescript 将 'auto' 视为此对象中的 string 类型:

return {
  observer: true,
  direction: 'vertical',
  slidesPerView: 'auto',
  freeMode: true,
  ...
};

您可以强制编译器将其视为 'auto' 类型的值，方法是强制转换它:

slidesPerView: 'auto' as 'auto',