[英]Generic type array of objects in typescript
Give then following:然后给出以下内容:
interface Datum {
[k: string]: any
}
type Data = Datum[]
const inner = (data: Data) => {
console.log(data)
};
const outer = (data: Data | Data[]) => {
inner(data) // expect type error?
};
I dont understand how I dont get a type error
on the inner function call
.我不明白如何在inner function call
没有收到type error
。 I guess it has something to do with the generic
.我想这与generic
. Cant figure out a way of rewriting.想不出重写的方法。
The Datum
interface is just too broad. Datum
界面实在是太宽泛了。 It will represent basically any object (ie indexable by a string and the result of the indexing operation is any
).它将基本上代表任何对象(即可由字符串索引并且索引操作的结果是any
)。
Given the object type is soo wide, both Datum
and Datum[]
and Datum[][]
are assignable to an array type, and thus you don't get any error.鉴于对象类型太宽, Datum
和Datum[]
和Datum[][]
都可以分配给数组类型,因此您不会收到任何错误。 Make the interface a bit more specific and you get an error.使界面更具体一点,你会得到一个错误。 Ex:前任:
interface Datum {
[k: string]: boolean | number | string;
}
type Data = Datum[]
const inner = (data: Data) => {
console.log(data)
};
const outer = (data: Data | Data[]) => {
inner(data) // error now
};
Or as @PatrickRoberts mentions in comments you can add a number
index to the interface to make it explicitly incompatible with an array:或者正如@PatrickRoberts 在评论中提到的,您可以向接口添加number
索引以使其与数组明确不兼容:
interface Datum {
[i: number]: never
[k: string]: any;
}
type Data = Datum[]
const inner = (data: Data) => {
console.log(data)
};
const outer = (data: Data | Data[]) => {
inner(data) // error
};
The best option would probably be using directly the object
interface instead of Datum
:最好的选择可能是直接使用object
接口而不是Datum
:
interface Datum {
[k: string]: any
};
// This is an object interface.
type Data = object[]; // instead of Datum[]
const inner = (data: object[]) => {
console.log(data)
};
Pd: I was looking for a solution for this same issue, used the solution from @titian-cernicova-dragomir which worked nicely. Pd:我一直在为同样的问题寻找解决方案,使用了@titian-cernicova-dragomir 的解决方案,效果很好。 I ended up finding the object interface being used in the react-csv
library.我最终找到了在react-csv
库中使用的对象接口。
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