Typescript Typecast现有变量

Question

假设我正在使用以下类型的模块：

interface AwesomeLibrary {
    name: string;
    query: Object;
}

我想将query类型转换到另一个界面：

interface Query {
    startDate: string;
    endDate: string;
    showAll: boolean;
}

假设有一个函数回调为我提供了AwesomeLibrary 。 然后，我想将query类型转换为Query 。 现在，这就是我所拥有的：

functionCb(response: AwesomeLibrary) {
    // This works fine
    let query: Query = response.query as Query;
    // Now, query.startDate is available
    // Do stuff to query
    // At the end, I want to send response back to another function, so I do
    response.query = query;
    otherFunction(response);

    // This does not work, but basically what I want:
    response.query = response.query as Query;
    // Then do stuff to response.query directly
    // Here response.query.startDate is not available, instead I have to use response.query['startDate']

    // Even this does not work:
    let query: Query = response.query as Query;
    response.query = query;
}

有什么想法吗？

Answer 1

您可以像这样键入强制转换：

(response.query as Query).startDate = (new Date()).toUTCString();

或者，您可以使用另一个变量：

let response2 = response as AwesomeLibrary & { query: Query };
response2.query.startDate = (new Date()).toUTCString();

您还可以使用以下类型的参数：

function functionCb(response: AwesomeLibrary & { query: Query }) {
    response.query.startDate = (new Date()).toUTCString();
}

但是随后您需要在调用此函数时进行强制转换。