What is the best way to create an array of strings that can include multiple elements from a set of strings?

Question

What is the best way to create an array of strings that can include multiple elements from a set of strings?

Exploring different roles for authorization:

['admin', 'manager', 'user']

Is there a way to create a specific type, named Roles, which is essentially a string array ( string[] ) that is limited to only containing values from the list of roles mentioned above? It should also be able to be an empty array.

Edit: Here is my initial attempt at defining this:

type Roles = [] | ['user'] | ['manager'] | ['admin'] | ['user', 'manager'] | ['user', 'admin'] | ['manager', 'admin'] | ['user', 'manager', 'admin']

However, this structure does not allow for:

const roles:Roles = ['admin','user']

Furthermore, if there are 4 roles, it becomes cumbersome as the number of options increase exponentially and it does not support variations in position within the list.

typescript

Answer 1

Answer №1

To start, establish a type called Position that can only be 'employee', 'supervisor', or 'manager' as shown below:

type Position = 'employee' | 'supervisor' | 'manager';
type Positions = Set<Position>;
//If there are multiple 'supervisor' positions in the list, Set will eliminate duplicates and keep the first instance
//resulting in a unique set of roles with supervisor role being distinct
const uniquePositionSet: Positions = new Set<Position>(['employee', 'manager', 'supervisor', 'supervisor']);

Next, define another type that represents a Set containing instances of the Position type.

Answer 2

To start, establish a type called Position that can only be 'employee', 'supervisor', or 'manager' as shown below:

type Position = 'employee' | 'supervisor' | 'manager';
type Positions = Set<Position>;
//If there are multiple 'supervisor' positions in the list, Set will eliminate duplicates and keep the first instance
//resulting in a unique set of roles with supervisor role being distinct
const uniquePositionSet: Positions = new Set<Position>(['employee', 'manager', 'supervisor', 'supervisor']);

Next, define another type that represents a Set containing instances of the Position type.

Answer 3

Answer №2

To simplify your code, consider using an enum to define the possible values and include functions for converting between strings and the custom enum.

For example:

enum UserRole {
    Admin = 'admin',
    Manager = 'manager',
    User = 'user',
}
type UserRoles = UserRole[]

const userRoles: UserRoles = [UserRole.Admin, UserRole.User]

Here is a conversion example (refer to How do I convert a string to enum in TypeScript? for more information):

function convertToRole(name: string): UserRole {
    return name as keyof typeof UserRole
}

const convertedUserRoles: UserRoles = [convertToRole('admin'), convertToRole('user')]
const roleName = UserRole[UserRole.Admin] // 'admin'

Refer to the TypeScript documentation at https://www.typescriptlang.org/docs/handbook/enums.html#string-enums for further details.

Answer 4

To simplify your code, consider using an enum to define the possible values and include functions for converting between strings and the custom enum.

For example:

enum UserRole {
    Admin = 'admin',
    Manager = 'manager',
    User = 'user',
}
type UserRoles = UserRole[]

const userRoles: UserRoles = [UserRole.Admin, UserRole.User]

Here is a conversion example (refer to How do I convert a string to enum in TypeScript? for more information):

function convertToRole(name: string): UserRole {
    return name as keyof typeof UserRole
}

const convertedUserRoles: UserRoles = [convertToRole('admin'), convertToRole('user')]
const roleName = UserRole[UserRole.Admin] // 'admin'

Refer to the TypeScript documentation at https://www.typescriptlang.org/docs/handbook/enums.html#string-enums for further details.

What is the best way to create an array of strings that can include multiple elements from a set of strings?

Answer №1

Answer №2

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