如何过滤对象数组，然后返回特定属性？

Question

consider the data :

let orders = {
        "data": [
            {
                "email": "a@b.com", "orders": [
                    { "orderName": "something", "price": "43$" },
                    { "orderName": "anotherthing", "price": "4$" }
                ]
            },{
                "email": "c@w.com", "orders": [
                    { "orderName": "fish", "price": "43$" },
                    { "orderName": "parrot", "price": "4$" }
                ]
            }
        ]
    };

I'm trying to filter the orders of the object with some email like:

email = 'a@b.com'
x=orders.data.filter(o =>{if (o.email === email) return o.orders});

but the whole return value is the whole matching object, with email and orders, and I don't want the whole object , I want only the orders.

Answer 1

您不能单独使用filter ，还需要map ：

orders.data.filter(o => o.email === 'a@b.com').map(o => o.orders)

Answer 2

An alternative is to use find and then just reference orders when needed. Adding || {'orders': 'Email not found'}; || {'orders': 'Email not found'}; after will catch if the email isn't found

 let orders = { "data": [{ "email": "a@b.com", "orders": [{ "orderName": "something", "price": "43$" }, { "orderName": "anotherthing", "price": "4$" } ] }, { "email": "c@w.com", "orders": [{ "orderName": "fish", "price": "43$" }, { "orderName": "parrot", "price": "4$" } ] }] }; email = 'a@b.com' x = orders.data.find(o => { return o.email === email }) || { 'orders': 'Email not found' }; console.log(x.orders); email = 'x@y.com' x = orders.data.find(o => { return o.email === email }) || { 'orders': 'Email not found' }; console.log(x.orders); 

Answer 3

You cannot do this with .filter as the method will only return a subsection if the array, while you want to also transform it.

You can chain Array#filter with Array#map to produce the result:

 let orders = { "data": [{ "email": "a@b.com", "orders": [{ "orderName": "something", "price": "43$" }, { "orderName": "anotherthing", "price": "4$" } ] }, { "email": "c@w.com", "orders": [{ "orderName": "fish", "price": "43$" }, { "orderName": "parrot", "price": "4$" } ] }]}; email = 'a@b.com'; x = orders.data .filter(o => o.email === email) .map(o => o.orders); console.log(x); 

If you expect a single element here, you can use Array#find instead:

 let orders = { "data": [{ "email": "a@b.com", "orders": [{ "orderName": "something", "price": "43$" }, { "orderName": "anotherthing", "price": "4$" } ] }, { "email": "c@w.com", "orders": [{ "orderName": "fish", "price": "43$" }, { "orderName": "parrot", "price": "4$" } ] }]}; email = 'a@b.com'; x = orders.data .find(o => o.email === email) .orders; console.log(x); 

Answer 4

 let orders = { "data": [ { "email": "a@b.com", "orders": [ { "orderName": "something", "price": "43$" }, { "orderName": "anotherthing", "price": "4$" } ] },{ "email": "c@w.com", "orders": [ { "orderName": "fish", "price": "43$" }, { "orderName": "parrot", "price": "4$" } ] } ] }; const filteredOrders = orders.data.map((o) => o.email === 'a@b.com' ? o.orders : null).filter(o => o); console.log(filteredOrders) 

You can map first too and filter after that the valid results.