The specified type 'BallInterface' must have 2 type arguments specified

Question

The specified type 'BallInterface' must have 2 type arguments specified

Currently on my Typescript learning journey, I encountered an error that states

Generic type 'BallInterface' requires 2 type argument(s)

in relation to tennisBall. How can I properly call a function with an object parameter containing multiple generic types? What is causing this error to be thrown? Below is the complete code snippet:

const addId = <T extends object>(obj: T) =>{ 
    const id = 3;
    return {
        ...obj,
        id
    }
}

interface BallInterface<T, V>{
    name: string
    data: T
    meta: V
}

const ball: BallInterface<{meta: string}, string> = {
    name: "Tennis",
    data:{meta: "for playing"},
    meta: "Mario"
}

const tennisBall = addId<BallInterface>(ball);

typescript

Answer 1

Answer №1

The reason for the error is due to your definition of BallInterface as an interface with two generics.

When you call addId on the last line, you are passing BallInterface as a generic without specifying the values that T and V should have.

It's not entirely clear what you are trying to accomplish here. If all you need to do is add the field Id, there is no need to provide a generic to addId at all. You are overcomplicating things unnecessarily :)

const addId = (obj: object) =>{
    const id = 3;
    return {
        ...obj,
        id
    }
}

interface BallInterface<T, V>{
    name: string
    data: T
    meta: V
}

const ball: BallInterface<{meta: string}, string> = {
    name: "Soccer",
    data:{meta: "for playing"},
    meta: "Ronaldo"
}

const soccerBall = addId(ball);

Answer 2

The reason for the error is due to your definition of BallInterface as an interface with two generics.

When you call addId on the last line, you are passing BallInterface as a generic without specifying the values that T and V should have.

It's not entirely clear what you are trying to accomplish here. If all you need to do is add the field Id, there is no need to provide a generic to addId at all. You are overcomplicating things unnecessarily :)

const addId = (obj: object) =>{
    const id = 3;
    return {
        ...obj,
        id
    }
}

interface BallInterface<T, V>{
    name: string
    data: T
    meta: V
}

const ball: BallInterface<{meta: string}, string> = {
    name: "Soccer",
    data:{meta: "for playing"},
    meta: "Ronaldo"
}

const soccerBall = addId(ball);

The specified type 'BallInterface' must have 2 type arguments specified

Answer №1

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