[英]How to get property using function of a typed object in typescript
Here is the interface:这是界面:
interface {
State?: string;
Profession?: string;
}
Now I want to use the getProperty function to get the value based on key of object.现在我想使用 getProperty function 根据 object 的键获取值。
function getProperty<Context, K extends keyof Context>(obj: Context, key: K): Context[K] {
return obj[key];
}
let key: string = 'State';
getProperty(context, key);
Now it returns the error现在它返回错误
> TSError: ⨯ Unable to compile TypeScript: index.ts:50:33 - error
> TS2345: Argument of type 'string' is not assignable to parameter of
> type '"State" | "Profession"'.
How should i solve this?我应该如何解决这个问题?
Remove the key:string
part删除key:string
部分
let key:any = 'State'
getProperty
function defined 2nd parameter key
as keyof Context
, so you need to define variable key
in a similar way: getProperty
function 将第二个参数key
定义为keyof Context
,因此您需要以类似的方式定义变量key
:
let key: keyof IContext = 'State';
Assuming that IContext
is the name of your interface.假设IContext
是您的接口的名称。 Full example would look like this:完整示例如下所示:
interface IContext {
State?: string;
Profession?: string;
}
function getProperty<Context, K extends keyof Context>(obj: Context, key: K): Context[K] {
return obj[key];
}
let key: keyof IContext = 'State'; // should not be a string
const context: IContext = {}; // instance of IContext
getProperty(context, key);
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