TS2322：类型“字符串”不可分配给类型“布尔”

Question

I have problem with binary, even if add brackets to it.

I'm using primeNG library.

In HTML file I wrote this code:

<div class="products-page">
    <div class="p-grid">
      <div class="p-col-3" *ngIf="!isCategoryPage">
        <h4>Categories</h4>
        <div class="p-field-checkbox" *ngFor="let category of categories">
          <p-checkbox
            [(ngModel)]="category.checked"
            binary="true"
            [inputId]="category.id"
            (onChange)="categoryFilter()"
          ></p-checkbox>
          <label for="{{ category.id }}">{{ category.name }}</label>
        </div>
      </div>
      <div [ngClass]="{ 'p-col-9': !isCategoryPage, 'p-col-12': isCategoryPage }">
        <div class="p-grid" *ngIf="products">
          <div
            [ngClass]="{ 'p-col-4': !isCategoryPage, 'p-col-3': isCategoryPage }"
            *ngFor="let product of products"
          >
            <products-product-item [product]="product"></products-product-item>
          </div>
        </div>
      </div>
    </div>
  </div>

,,,,

In ts file:

import { Component, OnInit } from '@angular/core';
import { Product, Category } from '@bluebits/products';
import { ProductsService } from '../../services/products.service';
import { CategoriesService } from '../../services/categories.service';
import { ActivatedRoute } from '@angular/router';

@Component({
  selector: 'products-list',
  templateUrl: './products-list.component.html'
})
export class ProductsListComponent implements OnInit {

  products: Product[] = [];
  categories: Category[] = [];
  isCategoryPage: boolean;

  constructor(
    private prodService: ProductsService,
    private catService: CategoriesService,
    private route: ActivatedRoute
    ) { }

  ngOnInit(): void {
    this.route.params.subscribe((params) => {
      params.categoryid ? this._getProducts([params.categoryid]) : this._getProducts();
      params.categoryid ? (this.isCategoryPage = true) : (this.isCategoryPage = false);
    });
    this._getCategories();
  }

  private _getProducts(categoriesFilter?: string[]) {
    this.prodService.getProducts(categoriesFilter).subscribe((resProducts) => {
      this.products = resProducts;
    });
  }

  private _getCategories() {
    this.catService.getCategories().subscribe(
      (resCats) => {
        this.categories = resCats;
      }
    )
  }

  categoryFilter() {
    const selectedCategories = this.categories
      .filter((category) => category.checked)
      .map((category) => category.id);

    this._getProducts(selectedCategories);
  }
}

In module file:

I Import this module

import { CheckboxModule } from 'primeng/checkbox';

I got this error:

error TS2322: Type 'string' is not assignable to type 'boolean'.

binary="true"

How can I fix it?

Answer 1

When you do binary="true" , you're assigning a string to a property that expects a boolean. To pass the true boolean value rather than the "true" string you'll have to use the brackets syntax:

<p-checkbox [binary]="true" [(ngModel)]="checked"></p-checkbox>

Answer 2

尝试添加[value]="true"属性：

 <p-checkbox [(ngModel)]="category.checked" [binary]="true" [value]="true"></p-checkbox>

Answer 3

Just to clarify and add some references:

The binary attribute is a boolean property of the p-checkbox . Your angular template is attempting to set ( bind ) it to true (it might not seem evident at first glance that the attribute assignment binds a property, but as thedocs suggest: " In most cases, the target name is the name of a property, even when it appears to be the name of an attribute . ").

The samedoc proceeds to state:

The brackets, [], cause Angular to evaluate the right-hand side of the assignment as a dynamic expression. Without the brackets, Angular treats the right-hand side as a string literal and sets the property to that static value.

IE, w/o the brackets, 'binary' is assigned the 'true' string literal, which is then flagged as an assignment error by typescript. [binary]='true' triggers an evaluation of 'true' to the boolean value.

BTW, you might conclude that you can workaround the issue by using interpolation ( binary="{{true}}" ). Indeed the angular docs support this notion, stating that " Often interpolation and property binding can achieve the same results. ". It does however qualify that by noting that " when setting an element property to a non-string data value, you must use property binding ".

Answer 4

The Angular CDK has a useful concept of declaring your @Input() s as BooleanInput instead of boolean . This allows myProp="true" to work in addition to [myProp]=true .

The coerceBooleanProperty function ensures that the input value is a boolean.

Answer 5

I solved this by modifying the angularCompilerOptions inside the tsconfig.json file.

Remove the strictTemplates property if it is set.