[英]How to create an interface for object and array of objects in Angular 8 and type script?
[英]How to create object of type interface in angular 4?
我正在一家单页购物商店中工作,但遇到了一个小问题。 我一直在尝试定义接口类型的对象,但无法在此对象中保存任何值。
这是我的代码
interface ICartItem2 {
total_items: number;
total_sum: number;
}
items: Array<ICartItem> = []; //array of objects working fine
totals: ICartItem2; //this is my faulty object of type interface ICartItem2
total_items:number=0;
total_sum:number = 0;
cart: ICartItem;
broadcast_obj = {items:[],totals:{}}; //object to store array of objects and single object
主要问题是这条线
totals: ICartItem2;
它在声明时没有显示错误,但是在我将值存储在该对象中然后显示主对象时,在下一行显示未定义。
this.totals = {total_items:this.total_items,total_sum:this.total_sum}
console.log(this.broadcast_obj.totals); // showing undefined
我已经完成了对象数组的工作,并且工作正常
this.cart = {id:id, name: itemText, price: amount,quantity:1};
this.items.push(this.cart);
当我在控制台中显示时(this.broadcast_obj.items); //显示正常。
这是完整的代码
import { Component, OnInit } from '@angular/core';
import { DataService } from '../data.service';
interface ICartItem {
id: number;
name: string;
price: number;
quantity: number;
}
interface ICartItem2 {
total_items: number;
total_sum: number;
}
@Component({
selector: 'app-home',
templateUrl: './home.component.html',
styleUrls: ['./home.component.scss']
})
export class HomeComponent implements OnInit {
items: Array<ICartItem> = [];
totals: ICartItem2;
total_items:number=0;
total_sum:number = 0;
cart: ICartItem;
broadcast_obj = {items:[],totals:{}};
duplicate:ICartItem ;
constructor(private _data: DataService) { }
ngOnInit() {
//this.items_count = this.cart.length;
this._data.cast.subscribe(res => this.broadcast_obj = res);
this._data.changeCart(this.broadcast_obj);
}
additem(id,itemText,amount){
if(this.items.length==0){//no item in the array
this.cart = {id:id, name: itemText, price: amount,quantity:1};
this.items.push(this.cart);
}
else{
this.duplicate = this.items.find(x => x.id == id);//check if item already exists in the cart
if (this.duplicate === null || this.duplicate === undefined) { //item object not found in the array
this.cart = {id:id, name: itemText, price: amount,quantity:1};
this.items.push(this.cart);
}
else if(this.duplicate.id===id){
this.duplicate.quantity++;
}
}
this.broadcast_obj.items = this.items;
this.total_items++;
this.total_sum += amount;
this.totals = {total_items:this.total_items,total_sum:this.total_sum}
console.log(this.broadcast_obj.totals);
this._data.changeCart(this.broadcast_obj);
}
}
标头组件代码
import { Component, OnInit } from '@angular/core';
import { DataService } from '../data.service';
interface ICartItem {
id: number;
name: string;
price: number;
quantity: number;
}
interface ICartItem2 {
total_items: number;
total_sum: number;
}
@Component({
selector: 'app-header',
templateUrl: './header.component.html',
styleUrls: ['./header.component.scss']
})
export class HeaderComponent implements OnInit {
cart: Array<ICartItem> = [];
totals: ICartItem2;
total_items:number = 0;
total_sum:number = 0;
showHide: false;
constructor(private _data: DataService) {
}
ngOnInit() {
this._data.cast.subscribe(res =>{
this.cart = res.items;
this.total_items = res.totals.total_items;
//this.total_sum = res.totals.total_sum;
});
}
addClass(toggle) {
console.log(this.total_items);
this.showHide = toggle;
}
}
服务代码
import { Injectable } from '@angular/core';
import { BehaviorSubject } from 'rxjs/BehaviorSubject';
@Injectable()
export class DataService {
private cartobj = new BehaviorSubject<any>({});
cast = this.cartobj.asObservable();
constructor() { }
changeCart(item_param) {
this.cartobj.next(item_param);
}
}
您在填充items
的属性this.broadcast_obj
与this.items
。 但是,您没有对totals
属性进行初始化。 因此它显示为未定义。 如果执行console.log(this.totals)
您将获得正确的输出。 我相信您需要添加this.broadcast_obj.totals = this.totals;
之后this.totals = {total_items:this.total_items,total_sum:this.total_sum}
编辑
import { Component, OnInit } from '@angular/core';
import { DataService } from '../data.service';
interface ICartItem {
id: number;
name: string;
price: number;
quantity: number;
}
interface ICartItem2 {
total_items: number;
total_sum: number;
}
@Component({
selector: 'app-home',
templateUrl: './home.component.html',
styleUrls: ['./home.component.scss']
})
export class HomeComponent implements OnInit {
items: Array<ICartItem> = [];
totals: ICartItem2;
total_items:number=0;
total_sum:number = 0;
cart: ICartItem;
broadcast_obj = {items:[],totals:{}};
duplicate:ICartItem ;
constructor(private _data: DataService) { }
ngOnInit() {
//this.items_count = this.cart.length;
this._data.cast.subscribe(res => this.broadcast_obj = res);
this._data.changeCart(this.broadcast_obj);
}
additem(id,itemText,amount){
if(this.items.length==0){//no item in the array
this.cart = {id:id, name: itemText, price: amount,quantity:1};
this.items.push(this.cart);
}
else{
this.duplicate = this.items.find(x => x.id == id);//check if item already exists in the cart
if (this.duplicate === null || this.duplicate === undefined) { //item object not found in the array
this.cart = {id:id, name: itemText, price: amount,quantity:1};
this.items.push(this.cart);
}
else if(this.duplicate.id===id){
this.duplicate.quantity++;
}
}
this.broadcast_obj.items = this.items;
this.total_items++;
this.total_sum += amount;
this.totals = {total_items:this.total_items,total_sum:this.total_sum}
console.log(this.totals) //Should give you valid log
this.broadcast_obj.totals = this.totals; //Added as per my answer
console.log(this.broadcast_obj.totals);
this._data.changeCart(this.broadcast_obj);
}
}
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