What is the best way to allocate string types from an enum using Typescript?

Question

What is the best way to allocate string types from an enum using Typescript?

Within my code, I have an enum that includes a collection of strings

export enum apiErrors {
    INVALID_SHAPE = "INVALID_SHAPE",
    NOT_FOUND = "NOT_FOUND",
    EXISTS = "EXISTS",
    INVALID_AUTH = "INVALID_AUTH",
    INTERNAL_SERVER_ERROR = "INTERNAL_SERVER_ERROR"
}

I have created an interface as follows:

export interface IApiResponse {
    status: boolean;
    payload: any;
    errorCode?: string; // I would like this to only accept values like "INVALID_SHAPE" or "NOT_FOUND" and so forth...
}

I am aware that I could simply use "INVALID_SHAPE" | "NOT_FOUND"

Is there a method to destructure the enum for errorCode in order to restrict it to accept only those specific strings?

typescript

Answer 1

Answer №1

When setting the errorCode to the apiErrors enum, as pointed out by @JBNizet and @AviadP, Typescript ensures that any implementation of the IApiResponse interface must have the errorCode assigned one of those predefined values.

export enum apiErrors {
   INVALID_SHAPE = "INVALID_SHAPE",
   NOT_FOUND = "NOT_FOUND",
   EXISTS = "EXISTS",
   INVALID_AUTH = "INVALID_AUTH",
   INTERNAL_SERVER_ERROR = "INTERNAL_SERVER_ERROR"
}

export interface IApiResponse {
   status: boolean;
   payload: any;
   errorCode?: apiErrors // this is the change
}

// example of invalid response
const invalidResponse: IApiResponse = {
   status: false,
   payload: {foo: 'bar'},
   errorCode: 'something not in the enum',
};

// valid response
const validResponse: IApiResponse = {
   status: false,
   payload: {foo: 'bar'},
   errorCode: apiErrors.INVALID_SHAPE,
};

// another valid response with no errorCode specified
const anotherValidResponse: IApiResponse = {
   status: true,
   payload: {foo: 'bar'},
   // errorCode isn't included at all
};

Answer 2

When setting the errorCode to the apiErrors enum, as pointed out by @JBNizet and @AviadP, Typescript ensures that any implementation of the IApiResponse interface must have the errorCode assigned one of those predefined values.

export enum apiErrors {
   INVALID_SHAPE = "INVALID_SHAPE",
   NOT_FOUND = "NOT_FOUND",
   EXISTS = "EXISTS",
   INVALID_AUTH = "INVALID_AUTH",
   INTERNAL_SERVER_ERROR = "INTERNAL_SERVER_ERROR"
}

export interface IApiResponse {
   status: boolean;
   payload: any;
   errorCode?: apiErrors // this is the change
}

// example of invalid response
const invalidResponse: IApiResponse = {
   status: false,
   payload: {foo: 'bar'},
   errorCode: 'something not in the enum',
};

// valid response
const validResponse: IApiResponse = {
   status: false,
   payload: {foo: 'bar'},
   errorCode: apiErrors.INVALID_SHAPE,
};

// another valid response with no errorCode specified
const anotherValidResponse: IApiResponse = {
   status: true,
   payload: {foo: 'bar'},
   // errorCode isn't included at all
};

What is the best way to allocate string types from an enum using Typescript?

Answer №1

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