A data type that exclusively accepts values from an enumerated list without mandating the inclusion of every possible value within the enum

Question

Here's a code snippet I'm working with:

enum Foo {
  a,
  b,
  c
}

type Bar = {
  [key in keyof typeof Foo]: string;
}

const test: Bar = {
  a: 'a',
  b: 'b'
};

I'm encountering an issue where the code is complaining about the missing c property in the test variable.

Any suggestions on how to adjust the Bar type so that the keys from the enum are optional?

Answer 1

Answer №1

If you want to create a more flexible type, you can utilize the Partial<T>:

enum Example {
  x,
  y,
  z
}

type Data = Partial<{
  [key in keyof typeof Example]: string;
}>

const exampleData: Data = {
  x: 'x',
  y: 'y'
};

Alternatively, as suggested by @jcalz in the comments, you can specify properties as optional:

enum Example {
  x,
  y,
  z
}

type Data = {
  [key in keyof typeof Example]?: string;
}

const exampleData: Data = {
  x: 'x',
  y: 'y'
};

Answer 2

If you want to create a more flexible type, you can utilize the Partial<T>:

enum Example {
  x,
  y,
  z
}

type Data = Partial<{
  [key in keyof typeof Example]: string;
}>

const exampleData: Data = {
  x: 'x',
  y: 'y'
};

Alternatively, as suggested by @jcalz in the comments, you can specify properties as optional:

enum Example {
  x,
  y,
  z
}

type Data = {
  [key in keyof typeof Example]?: string;
}

const exampleData: Data = {
  x: 'x',
  y: 'y'
};

Answer 3

One of the easiest solutions is to use utility types like Partial and Record

type Example = Partial<Record<keyof typeof Bar, string>>

Answer 4

One of the easiest solutions is to use utility types like Partial and Record

type Example = Partial<Record<keyof typeof Bar, string>>