Question

我是较新的角度显影器，我具有以下要求的角度cli规格 -Angular CLI：7.0.7节点：10.13.0 OS：win32 x64 Angular：7.0.4 但是有1个错误发生。错误是

src / app / products / products.component.ts（28,12）中的
ERROR：错误TS2322：类型“ {}”不可分配给类型“产品[]”。属性“长度” 类型“ {}”中缺少。

product.component.ts

import { Product } from 'src/app/models/product';
import { ActivatedRoute } from '@angular/router';
import { CategoryService } from './../category.service';
import { ProductService } from './../product.service';
import { Component } from '@angular/core';
import 'rxjs/add/operator/switchMap';


@Component({
  selector: 'app-products',
  templateUrl: './products.component.html',
  styleUrls: ['./products.component.css']
})
export class ProductsComponent {
  products: Product[] = [];
  filteredProducts: Product[] = [];
  categories$;
  category: string;

  constructor(
    route: ActivatedRoute,
    productService: ProductService,
    categoryService: CategoryService
  ) {
    productService
      .getAll()
      .switchMap(products => {
        this.products = products;
        return route.queryParamMap;
      })

      .subscribe(params => {
        this.category = params.get('category');

        this.filteredProducts = (this.category) ?
          this.products.filter(p => p.category === this.category) :
          this.products;
      });

    this.categories$ = categoryService.getAll();
  }
}

以下行.switchMap（products => { this.products =产品； //此行发生错误返回route.queryParamMap;

Answer 1

正确的方法是像这样在您的服务中添加键入内容

class ProductService {
  getAll() {
    this.http.get<Product[]>(...);
  }
}

这会将您的响应类型转换为Observable<Product[]>，错误将消失

Answer 2

您可能想要更改

.switchMap(products => {
...
}

到

.switchMap((products: Product[]) => {
...
}

不能将类型“ {}”分配给类型“ Product []”的角度发生错误。类型“ {}”中缺少属性“长度”

2 个答案: