CODEWITHSUNDEEP
typescript
dagda1
dagda1

Reputation: 28810

specify object fields are a property of an enum

How can I type the following structure:

const fields: any = {
  [AuthForms.LoginForm]: ['email', 'password'],
  [AuthForms.ForceChangePasswordForm]: ['password', 'confirmPassword'],
  [AuthForms.ForgottenPasswordForm]: ['email'],
  [AuthForms.ResetPasswordForm]: ['email', 'password', 'confirmPassword']
};

I have tried below but cannot quite get the syntax right

const fields: { [keyof AuthForms]: string[] } = {
  [AuthForms.LoginForm]: ['email', 'password'],
  [AuthForms.ForceChangePasswordForm]: ['password', 'confirmPassword'],
  [AuthForms.ForgottenPasswordForm]: ['email'],
  [AuthForms.ResetPasswordForm]: ['email', 'password', 'confirmPassword']
};

Upvotes: 1

Views: 36

Answers (1)

kingdaro
kingdaro

Reputation: 12018

For the record, you should be able to leave off the type annotation entirely, and use the type inferred by TS. That's what I'd personally do, but if you can't for whatever reason...

Index signatures (the { [key: string]: SomeType } syntax) only accepts the types string and number for the key. In order to specify specific keys, you'll need to use a mapped type.

Remember: to specify the type for a key of SomeEnum, you only need to type SomeEnum, so no keyof is needed here.

const fields: { [K in AuthForms]: string[] } = {

You can also opt for the more readable Record type, which was made for simple cases like this. This does the same as the above:

const fields: Record<AuthForms, string[]> = {

Upvotes: 1

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