打字稿：是否有一种简单的方法可以将一种类型的对象数组转换为另一种类型

Question

So, I have two classes

Item { name: string; desc: string; meta: string}

ViewItem { name: string; desc: string; hidden: boolean; }

I have an array of Item that needs to be converted into an array of ViewItem. Currently, I am looping through the array using for, instantiating ViewItem, assigning values to attributes and pushing it to the second array.

Is there a simple way to achieve this using lambda expressions? (similar to C#) Or is there any other means?

Answer 1

You haven't showed enough of your code, so I'm not sure how you instantiate your classes, but in any case you can use the array map function :

class Item {
    name: string;
    desc: string;
    meta: string
}

class ViewItem {
    name: string;
    desc: string;
    hidden: boolean;

    constructor(item: Item) {
        this.name = item.name;
        this.desc = item.desc;
        this.hidden = false;
    }
}

let arr1: Item[];
let arr2 = arr1.map(item => new ViewItem(item));

( code in playground )

---

Edit

This can be shorter with Object.assign :

constructor(item: Item) {
    Object.assign(this, item);
}

Answer 2

An alternate method is to use Object.keys ,

class Item {
    name: string;
    desc: string;
    meta: string
}

class ViewItem {
    name: string;
    desc: string;
    hidden: boolean;

    // additional properties
    additionalProp: boolean;

    constructor(item: Item) {
        Object.keys(item).forEach((prop) => { this[prop] = item[prop]; });

        // additional properties specific to this class
        this.additionalProp = false;
    }
}

Usage:

let arr1: Item[] = [
    {
        name: "John Doe",
        desc: "blah",
        meta: "blah blah"
    }
];
let arr2: ViewItem[] = arr1.map(item => new ViewItem(item));

Playground link

Answer 3

you can do use something like this.

const newdata = olddata.map((x) => {
        return { id: Number(x.id), label: x.label };
      });

as the converted column will be mapped to the newdata array.