类型“{}”缺少类型 ts(2739) 中的以下属性

Question

I have a function that makes structured data from rawData (from API)

function makeData(raw:typeof rawData){
    const data:IData = {} // this line throws above error.

    const now = new Date()
    data.createdAt=now.toDateString();
    data.currentUser=raw.name;
    data.uniqueId= raw.id + now.toDateString();

    return data
}

As I am making the data, I am using an empty object in the beginning and typing it with IData so that the return value from the function is typed as IData . But as mentioned this is throwing error.

interface IData {
    createdAt:string;
    currentUser:string;
    uniqueId:string;
}

Usage:

const {createdAt, currentUser,uniqueId} = makeData(rawData)

I tried to remove IData completely then I got the following error.

Property 'createdAt' does not exist on type '{}'. // got the same error for other properties as well ( currentUser, uniqueId )

Getting the same error(s) on the line where destructing is done.

I got a workaround for now:

const data : Record<string,unknown>= {}

But this doesn't seem to be more convincing for me.

Is there a better way to type data as IData.

Live Demo .

Answer 1

you can't define a const of IData without specify the data inside of it, instead you can do something like this

function makeData(raw: typeof rawData): IData{
    const now = new Date()
    
    return {
        createdAt: now.toDateString(),
        currentUser: raw.name,
        uniqueId: raw.id + now.toDateString()
    }
    
}

Answer 2

Here as you are annotating data as IData . It expects the object to contain all the required properties. (in this case: createdAt, currentUser, uniqueId)

You can do 2 things.

1: You can do type assertion.

const data = {} as IData.

2: Initialise the object with empty values.

const data:IData = {
  createdAt:"",
  currentUser:"",
  uniqueId:""
 }

Answer 3

That's happen because all the propertys inside IData are required, so if you define a variable of type IData you need to provide it the values

Maybe you can use the UtilityType Partial or define what type are you going to return

function makeData(raw: typeof rawData): IData { }

The comment by @mikrowdev is the best solution for this i think.