Theo's Typesafe Cult•2y ago

Derive Type from Parameter of function attach to object (possibly recursive idk)

Hey Guys, so to explain what I'm doing, I'm basically defining a data structure to plug into a function of mine. The data structure is a key value and a class object that is defined on the fly. Like this

const AccountValidation: ValidationShape = {
    username: Validation.new('').length(5),
    password: Validation.new('').length(5)
}

const AccountValidation: ValidationShape = {
    username: Validation.new('').length(5),
    password: Validation.new('').length(5)
}

The Validation.new() function is used to define the default value for each field and instantiate an object to build my validation strategy.

type ValidationShape = {
    [key: string ]: Validation<unknown>
}

type ValidationShape = {
    [key: string ]: Validation<unknown>
}

This is the ValidationShape type and here is the Validation object class

export class Validation<T> {
    default: T;
    ValidationQueue: ValidationMethod[] = [];

    constructor(val: T) {
        this.default = val;
    }

    length(min: number, max?: number) {
        this.ValidationQueue.push({
            method: 'length',
            min,
            max

        })
        return this;
    }

    getDefaultValue(): T {
        return this.default;
    }

    getValidationQueue(): ValidationMethod[] {
        return this.ValidationQueue;
    }

    static new<T>(val: T) {
        return new Validation(val);
    }

export class Validation<T> {
    default: T;
    ValidationQueue: ValidationMethod[] = [];

    constructor(val: T) {
        this.default = val;
    }

    length(min: number, max?: number) {
        this.ValidationQueue.push({
            method: 'length',
            min,
            max

        })
        return this;
    }

    getDefaultValue(): T {
        return this.default;
    }

    getValidationQueue(): ValidationMethod[] {
        return this.ValidationQueue;
    }

    static new<T>(val: T) {
        return new Validation(val);
    }

So this is the object attached to each invidual key fpr my ValidationShape object. Now, I would like to take this shape, iterate over it and get the default value and its type and then take those values to create a new shape that is the key: ReturnType<GetDefaultValue>

type Reshape = {
    [Property in keyof ValidationShape]: ReturnType<Property['getDefaultValue']>
}


const T: Reshape = {
    username: "usernme",
    password: "passwrd",
}

type Reshape = {
    [Property in keyof ValidationShape]: ReturnType<Property['getDefaultValue']>
}


const T: Reshape = {
    username: "usernme",
    password: "passwrd",
}

Notice the reshape version is now just strings, since each new call was called with an empty string.

1 Reply

benten•2y ago

Sorry, what's the issue here?

Gaming

Programming

Derive Type from Parameter of function attach to object (possibly recursive idk)