错误 TS2352：将类型 'Session | null' 转换为类型 '{ x: string; y: string; }' 可能是一个错误

Question

最初我得到了这些错误

server.ts:30:12 - error TS2339: Property 'shop' does not exist on type 'Session | null'.
30     const {shop, accessToken} = ctx.session;
~~~~
server.ts:30:18 - error TS2339: Property 'accessToken' does not exist on type 'Session | null'.
30     const {shop, accessToken} = ctx.session;
~~~~~~~~~~~

在写了const {shop, accessToken} = ctx.session as {shop: string, accessToken: string}之后，我看到了以下内容：

server.ts:48:31 - error TS2352: Conversion of type 'Session | null' to type '{ shop: string; accessToken: string; }' may be a mistake because neither type sufficiently overlaps with the other. If this was intentional, convert the expression to 'unknown' first.
Type 'Session' is missing the following properties from type '{ shop: string; accessToken: string; }': shop, accessToken
48   const {shop, accessToken} = ctx.session as {shop: string, accessToken: string};
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[4:52:59 AM] Found 4 errors. Watching for file changes.

我是Typescript的新手，但相信我有两个选项

1. 将行重写为const {shop, accessToken} = ctx.session as unknown as {shop: string, accessToken: string}
2. 为Session编写一个接口，并对其断言ctx.session(ctx.session as Session(，覆盖以前的类型赋值(session|null(

这是正确的吗？这里有什么更好的选择？

Answer 1

问题是"session"可以为null，而null不包含任何属性。

试试其中一个：

const {shop, accessToken} = ctx.session!;

或者：

if (ctx.session === null) { return; } // Or throw, or next()
const {shop, accessToken} = ctx.session;