Typescript：Getter無法返回具有自定義類型的數組

Question

我嘗試從getter返回具有自定義類型的數組時遇到錯誤。 這是錯誤消息：

Type 'Expense[]' is missing the following properties from type 'Expense': name, cost, priority

這是我的代碼：

import Expense from '../interfaces/expence';

class User {
  firstName: string;
  lastName: string;
  totalCost: number;
  private expenses: Expense[];
  constructor(firstName: string, lastName: string) {
    this.firstName = firstName;
    this.lastName = this.lastName;
  }
  set userExpenses(expence: Expense) {
    this.expenses = [...this.expenses, expence]
    this.totalCost += expence.cost
  }
  get userExpenses() {
    return this.expenses
  }
}
export default User;

interface Expense {
  name: string
  cost: number;
  priority: string,
}

export default Expense;

Answer 1

這里的問題是get和set必須具有相同的類型。 在您的情況下， set在單個Expense對象上工作，而get返回Expense[] 。

更好的解決方案是為setter創建一個append方法，因為以下代碼沒有意義

user.userExpenses = new Expense("1", 100, "1"); \\ it appends to expenses array

這就是我要做的

class User {
firstName: string;
lastName: string;
totalCost:number;
private expenses: Expense[] ;
constructor(firstName: string,lastName: string) {
    this.firstName = firstName;
    this.lastName = this.lastName;
}

set userExpenses(expences: Expense[]) { //assignment
    this.expenses = [...expences];   
    this.expenses.forEach(e => this.totalCost += e.cost);
}

get userExpenses() {
    return this.expenses
}

addExpences(expences: Expense[]) {  //append
    expences.forEach(e => this.totalCost += e.cost);
    this.expenses = [...this.expenses, ...expences];   
}

}