Retrieve the value of the Type Property dynamically during execution

Looking at this type generated from a graphql schema:

export type UserPageEntry = {
  readonly __typename?: 'UserPageEntry'
}

I am interested in retrieving the string representation of its only property type ('UserPageEntry') during compile time. This way, I can eliminate the hardcoded string 'UserPageEntry' in the code snippet below:

   cache.modify({
              optimistic: true,
              id: `UserPageEntry:${userId}`,

My goal was to utilize an indexed access type like so:

type x =  UserPageEntry['__typename']

... and then use it as ${x.toString()}:${userId},

Is there a way to access the default value of this property or is it wiped out?

typescript

Answer №1

Regrettably, Titian Cernicova-Dragomir emphasizes here:

You are unable to convert a type into a value.

Nevertheless, TypeScript can verify that the correct magic string is used:

const userPageEntryString: UserPageEntry["__typename"] = "UserPageEntry";

const id = `${userPageEntryString}:${userId}`;

Playground link

There are several ways this can be beneficial:

  • It helps catch typos
  • It ensures the accuracy of the magic string if 
    UserPageEntry["__typename"]
    changes during future refactoring

Here's an example demonstrating a typo (which also showcases both benefits):

const userPageEntryString: UserPageEntry["__typename"] = "UserPaegEntry";
// This results in an error as intended, since it is incorrect −−−−−−−−−−−−−−−−−−^^

Playground link

Similar questions

If you have not found the answer to your question or you are interested in this topic, then look at other similar questions below or use the search

When I apply filtering and grouping to the table, the rows in the mat table disappear

When using mat-table, grouping works fine without filtering. However, once the table is filtered or if the search bar is focused, ungrouping causes the rows in the table to disappear. I am looking for a solution that allows me to group and ungroup the tabl ...

angulartypescriptangular-materialgroupingmat-table

Strange Node.js: I always avoid utilizing `require()`, yet encountered an unexpected error

For more information on this particular issue, please refer to this link It's quite puzzling as I haven't used the require() function in my code, yet I'm receiving an error telling me not to use it. How odd! The problematic code snippet i ...

node.jstypescriptimportrequirees6-modules

Encountering difficulty importing TypeScript files dynamically within a Deno executable

When attempting to import a file from aws in an exe using its public link based on user input, I am facing difficulties For example, I generated my exe with the command below deno compile --allow-all main.ts Users execute this exe using commands like ./e ...

javascripttypescriptimportdeno

Is it possible to define a data type from an external package using TypeScript and Node.js?

I'm currently in the process of reorganizing some code to utilize a list of signals and connect `.once` handlers to each one individually. const terminationSignals = ["SIGINT", "SIGUSR2", "SIGTERM"]; terminationSignals.f ...

javascriptnode.jstypescript

AngularJS2 brings a powerful and seamless implementation of indexedDB for efficient

I'm on the hunt for an indexeddb implementation that works seamlessly with Angularjs2. While I stumbled upon this api at https://github.com/gilf/angular2-indexeddb, it appears to be lacking in active development and may not be ready for production use ...

typescriptangularindexeddb

What is the best way to establish communication with the root component in Angular?

I have implemented a modal in the root component that can be triggered from anywhere. However, I am facing a dilemma on how the bottom component can communicate with the top component without excessive use of callback functions. Root Component <contai ...

angulartypescript

I am encountering an issue where body-parser is not functioning properly with typescript. Whenever I make a request, the request.body is returning as undefined

Below is the code snippet for my Express application using TypeScript version 3.7.4: import bodyParser from "body-parser"; import config from "config"; import cookieParser from "cookie-parser"; import express from "express"; import mongoose from "mongoose ...

javascriptnode.jstypescriptexpressbody-parser

A comprehensive guide on extracting data from the query string in Angular

There is a specific query string format that we need to handle. The input parameter of the method comes in the form of a string and it's not an instance of ActivatedRoute. http://localhost:4200/users?param1=en&param2=nk I've attempted to rea ...

angulartypescript

What are some creative ways to emphasize certain dates?

Is there a way to customize mui-x-date-pickers to highlight specific days from a Date array with green filled circles around them? I am using new Date and wondering how to achieve this effect. Below is the code snippet I am currently working with: <Dat ...

reactjstypescriptmaterial-ui

Understanding the concept of inconsistent return points in Typescript: What implications does it carry?

I am currently working on converting a NodeJs JavaScript code to TypeScript. The code snippet below shows how I save uploaded files using JavaScript and now I'm encountering an error when trying to do the same in TypeScript. The error message says "Fu ...

node.jstypescript

I'm confused why this particular method within a class is not being inherited by the next class. Rather than seeing the expected extension, I am presented with - [Function (

Working fine with the Person class, the register() function displays the correct return statement when logged in the console. However, upon extending it to the Employee class, instead of the expected return statement, the console logs show [Function (anon ...

javascripttypescripttypescript-class

Exploring Computed Properties in Angular Models

We are currently in the process of developing an application that involves the following models: interface IEmployee{ firstName?: string; lastName?: string; } export class Employee implements IEmployee{ public firstName?: string; public l ...

angulartypescript

Images in Angular Firebase causing scroll problems in Chrome

In regard to Angular 6, a common issue arises with slow image loading specifically in Chrome, not other browsers. The project utilizes Firebase and the snapshotchange method to fetch images for the Angular project. Image URLs used are like this: . The iss ...

htmlangulartypescriptfirebasegoogle-chrome

"Embracing the power of multiple inheritance with Types

I am struggling with the concept of multiple inheritance in TypeScript. It doesn't make sense to overload a hierarchy with too much functionality. I have a base class and several branches in the hierarchy. However, I need to utilize mixins to isolate ...

typescriptmultiple-inheritance

Guide to incorporating @types/module with the corresponding npm module that has type definitions available

This is an example of a module I am currently utilizing in my project. I have come across TypeScript type definitions for the npm module polylabel, which can be found at https://github.com/mapbox/polylabel. When I run npm install --save @types/polylabel, ...

javascripttypescriptnpm

Guide to creating a universal interface using the generic class concept

I am in the process of developing a new augmented, generic interface that is based on an existing interface. The original interface sets out the properties that the object will possess (root). The enhanced type should also have these properties, but instea ...

typescripttypescript-generics

Challenges managing errors in Angular unit tests

As I continue to learn Angular, my search for information has yielded minimal results. However, one resource that stood out was a post on Stack Overflow titled How to write a test which expects an Error to be thrown in Jasmine? After reviewing the aforeme ...

angulartypescriptunit-testingjasmine

Angular: Implementing asynchronous data retrieval for templates

I am currently facing the following issue: I need to create a table with entries (Obj). Some of these entries have a file attribute. When an entry has a file attribute (entry.file), I need to make a backend call to retrieve the URL of that file: public g ...

htmlangulartypescriptrxjs

Enhancing search capabilities in Angular 8.1.2 by filtering nested objects

I am in need of a filter logic similar to the one used in the example posted on this older post, but tailored for a more recent version of Angular. The filtering example provided in the older post seems to fit my requirements perfectly, especially with ne ...

angulartypescriptangular-filtersangular-pipe

What is the best way to use Immer to update Zustand state when incorporating objects that are added through a controlled form using React-Hook-

Having some trouble with integrating Zustand and Immer using React-Hook-Form. My goal is to capture a series of values from a form, store them in a list, and allow for the addition of new objects to that list. In this scenario, the user inputs data for a ...

javascriptreactjsarraystypescript