I'm receiving the following in an API response:
{ "roles": [ "ADMIN", "USER" ] }
where the response will always contain an array of roles (USER, PRESENTER, ORGANIZER, and ADMIN).
I want to convert it into a valid TypeScript array (Role[]), where the type Role is defined as follows:
export type Role = 'USER' | 'PRESENTER' | 'ORGANIZER' | 'ADMIN'
Any ideas?
Your Role type is not an enum. It is just a string type limited to certain values.
You can just cast the result as a Role[] and TypeScript will be happy. This assumes the incoming data never has a bad value!
const data: {roles: Role[]} = JSON.parse('{"roles": ["ADMIN", "USER"]}');
data.roles // TypeScript knows it is a Role[]
if and you're done :)
if in an extensible way is tricky.ifs for youYou can just cast it to your union type:
const apiRoleArray = ["ADMIN", "USER"];
const realRoleArray: Role[] = <Role[]>apiRoleArray;
BUT you probably want to validate its contents rather than just trusting the API. :-) Drawing on this question's answers, you can create the type by using the keys of an object rather than defining it literally (see the accepted answer there for why):
const roleStrings = {
USER: "",
PRESENTER: "",
ORGANIZER: "",
ADMIN: ""
};
export type Role = keyof typeof roleStrings;
then give yourself a validation function:
const isRole = (s: string): s is Role => {
return roleStrings.hasOwnProperty(s);
};
then a robust conversion function, for example:
const rawToRoleArray = (rawArray: string[]): Role[] => {
return rawArray.map(s => {
if (!isRole(s)) {
throw new Error("Invalid Role: " + s);
}
return <Role>s;
});
};
(you could combine those if you don't need them separately)
then use it:
// Valid
const realRoleArray: Role[] = rawToRoleArray(["ADMIN", "USER"]);
console.log(realRoleArray);
// Invalid
const realRoleArray2: Role[] = rawToRoleArray(["ADMIN", "FOO"]);
console.log(realRoleArray2);
if I was talking about: if (!isRole(s)).
If I got you corectly thats what you want to do.
enum RoleEnum {
USER,
PRESENTER,
ORGANIZER,
ADMIN
}
const parseEnum = (name: String): RoleEnum => RoleEnum[`${name}`]
const parsed: RoleEnum[] = [ 'ADMIN', 'USER' ].map(parseEnum)
console.log(parsed)
presenter&organizercame into picture? ALso the expected output is not clearSymbols would be a good ideaRole[]? Is there an issue with using the usual cast usingas? EG, something likeconst roles = response.roles as Role[]?as Role[]