带有由接口定义的字符串键和内容的打字稿类型对象

Question

my data has this structure:

groups = {
    someGroupName: {
        total: 30,
        count: 3,
        average: 10
    },
    someOtherGroupName: {
        total: 60,
        count: 3,
        average: 20
    }
}

I can write an interface for the nested part:

interface Stats {
    total: number,
    count: number,
    average: number
}

but how can I set a type for groups as a whole? I do not know what groups are coming in. I just know that it will be a groupname as the key and the stats object as the value.

Answer 1

You can use an index signature to tell typescript that the object is indexable by any string but all values in the object are of a certain type:

interface Stats {
    total: number,
    count: number,
    average: number
}

interface Groups {
    [name: string] : Stats
}

let groups: Groups = {
    someGroupName: {
        total: 30,
        count: 3,
        average: 10
    },
    someOtherGroupName: {
        total: 60,
        count: 3,
        average: 20
    }
}

let someGroupName = groups['someGroupName'] //someGroup is Stats
groups['someGroupName'] = 0 // invalid 0 is not of type Stats 

Answer 2

Simpler way

You can use {[key:string]:string} as a type for any object with string values and string keys.

type strObj = {[key:string]:string}

const sample:strObj = {
    one:"text1",
    two:"text2"
}

For nested Object

And if it is a nested object, you can nest the type in place of string at the end.

{[key:string]: string } ==> {[key:string]: {[key:string]:string}}

Hence,

type strObj = {[key:string]:{[key:string]:string}}
const sample:strObj = {
    one:{
        sub:"text1"
    },
    two:{
        sub:"text2"
    }
}