Assign a true or false value to every attribute of an object

Question

Assign a true or false value to every attribute of an object

Imagine we have a scenario with an interface like this:

    interface User {
       Id: number;
       FirstName: string;
       Lastname: string;
       Age: number;
       Type: string;
    }

and a specific method for copying properties based on a flag.

    function copyIfAccepted<T extends object, K extends keyof T>(source: T, dest: T, key: K, 
  isAccepted: boolean) {
      if (isAccepted && source[key] !== dest[key]) {
        dest[key] = source[key];
      }
    }

Currently, the method is being called multiple times for each property. Keep in mind that not all properties are listed here.

     copyIfAccepted(oldUser, newUser, 'Id', true);
     copyIfAccepted(oldUser, newUser, 'FirstName', false);
     copyIfAccepted(oldUser, newUser, 'LastName', true);
     copyIfAccepted(oldUser, newUser, 'Age', true);

Is there a way to refactor this method so it only needs to be called once for all relevant properties? This should be done using TS 4.9

typescript

Answer 1

Answer №1

As previously stated in my comment, a helper type can be created to iterate over any type and convert it into an object with its attributes as booleans for the "isActive" part:

interface User {
  Id: number;
  FirstName: string;
  Lastname: string;
  Age: number;
}

type ToBooleanType<T> = {
  [P in keyof T]: boolean;
};

function copyIfAccepted<T extends object>(source: T, dest: T, checks: ToBooleanType<T>) {
  for (const key in source) {
    const sourceValue = source[key];
    const destValue = dest[key];
    const isAccepted = checks[key];

    if (isAccepted && sourceValue !== destValue) {
      dest[key] = sourceValue;
    }
  }
}
const user1: User = { Age: 21, FirstName: 'Joe', Id: 1, Lastname: 'Dirt' };
const user2: User = { Age: 26, FirstName: 'Jane', Id: 3, Lastname: 'Doe' };

copyIfAccepted(user1, user2, { Id: false, Age: true, FirstName: false, Lastname: true });

console.log(user1, user2);

Output:

[LOG]: {
  "Age": 21,
  "FirstName": "Joe",
  "Id": 1,
  "Lastname": "Dirt"
},  {
  "Age": 21,
  "FirstName": "Jane",
  "Id": 3,
  "Lastname": "Dirt"
}

This code demonstrates that only the checked attributes are copied over if they are different.

Typescript Playground

Answer 2

As previously stated in my comment, a helper type can be created to iterate over any type and convert it into an object with its attributes as booleans for the "isActive" part:

interface User {
  Id: number;
  FirstName: string;
  Lastname: string;
  Age: number;
}

type ToBooleanType<T> = {
  [P in keyof T]: boolean;
};

function copyIfAccepted<T extends object>(source: T, dest: T, checks: ToBooleanType<T>) {
  for (const key in source) {
    const sourceValue = source[key];
    const destValue = dest[key];
    const isAccepted = checks[key];

    if (isAccepted && sourceValue !== destValue) {
      dest[key] = sourceValue;
    }
  }
}
const user1: User = { Age: 21, FirstName: 'Joe', Id: 1, Lastname: 'Dirt' };
const user2: User = { Age: 26, FirstName: 'Jane', Id: 3, Lastname: 'Doe' };

copyIfAccepted(user1, user2, { Id: false, Age: true, FirstName: false, Lastname: true });

console.log(user1, user2);

Output:

[LOG]: {
  "Age": 21,
  "FirstName": "Joe",
  "Id": 1,
  "Lastname": "Dirt"
},  {
  "Age": 21,
  "FirstName": "Jane",
  "Id": 3,
  "Lastname": "Dirt"
}

This code demonstrates that only the checked attributes are copied over if they are different.

Typescript Playground

Assign a true or false value to every attribute of an object

Answer №1

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