Guidelines for segregating a Union from an Array

I'm currently utilizing graphql-code-generator to automatically generate TypeScript definitions from my GraphQL queries. I have a specific union within an array that I am trying to extract in TypeScript. Is this feasible? Although I came across an example where someone extracted a type from a generic object and attempted using the Extract function, it unfortunately returned just never:

export type Foo = Array<(
    {
      id: string;
      __typename: 'Data1'
    }
    | {
      id: string;
      __typename: 'Data2'
    }
  )>;

type MyQueryData1 = Extract<Foo, { __typename: "Data1"}>
type MyQueryData2 = Extract<Foo, { __typename: "Data2"}>

Explore TypeScript Playground

typescript

Answer №1

Are you satisfied with the outcome? ts playground

If this meets your requirements, you will need to extract the type from the derived union type based on the element values of the array,

type MyQueryData1 = Extract<Foo[number], { __typename: "Data1"}>
type MyQueryData2 = Extract<Foo[number], { __typename: "Data2"}>

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

Typescript fetch implementation

I've been researching how to create a TypeScript wrapper for type-safe fetch calls, and I came across a helpful forum thread from 2016. However, despite attempting the suggestions provided in that thread, I am still encountering issues with my code. ...

typescriptgenericsfetch

Is there a way to utilize a value from one column within a Datatables constructor for another column's operation?

In my Typescript constructor, I am working on constructing a datatable with properties like 'orderable', 'data' and 'name'. One thing I'm trying to figure out is how to control the visibility of one column based on the va ...

javascriptjquerytypescriptdatatable

What is the best method to create a TypeScript dictionary from an object using a keyboard?

One approach I frequently use involves treating objects as dictionaries. For example: type Foo = { a: string } type MyDictionary = { [key: string]: Foo } function foo(dict: MyDictionary) { // Requirement 1: The values should be of type Foo[] const va ...

typescripttypescript-typings

Leverage the power of ssh2-promise in NodeJS to run Linux commands on a remote server

When attempting to run the command yum install <package_name> on a remote Linux server using the ssh2-promise package, I encountered an issue where I couldn't retrieve the response from the command for further processing and validation. I' ...

javascriptjavanode.jstypescriptssh2

Error: 'Target is not found' during React Joyride setup

I am attempting to utilize React Joyride on a webpage that includes a modal. The modal is supposed to appear during step 3, with step 4 displaying inside the modal. However, I am encountering an issue where I receive a warning message stating "Target not m ...

reactjstypescript

Eliminating the "undefined" error in TypeScript within a React application

Having recently dived into TypeScript configuration, I encountered an issue when coding and tried to resolve it by encapsulating the code block in an if statement checking for usersData to eliminate the "Object is possibly undefined" errors. However, upon ...

reactjstypescriptundefined

Tips for utilizing generics to determine the data type of a property by its name

I am seeking a method to determine the type of any property within a class or a type. For instance, if I had the classes PersonClass and PersonType, and I wanted to retrieve the type of the nationalId property, I could achieve this using the following cod ...

typescriptgenericstypescript-typings

Using the Vue.js Compositions API to handle multiple API requests with a promise when the component is mounted

I have a task that requires me to make requests to 4 different places in the onmounted function using the composition api. I want to send these requests simultaneously with promises for better performance. Can anyone guide me on how to achieve this effic ...

javascripttypescriptvue.js

Troubleshooting: Unable to locate .vue.d.ts file during declaration generation with Vue, webpack, and TypeScript

Currently, I am developing a library using Typescript and VueJS with webpack for handling the build process. One of the challenges I'm facing is related to the generation of TypeScript declaration files (.d.ts). In my source code, I have Typescript ...

typescriptwebpackvue.js

Converting lengthy timestamp for year extraction in TypeScript

I am facing a challenge with extracting the year from a date of birth value stored as a long in an object retrieved from the backend. I am using Angular 4 (TypeScript) for the frontend and I would like to convert this long value into a Date object in order ...

javascriptangulartypescripttimestamp

Add a custom design to the Material UI menu feature

I am currently trying to implement a custom theme using the following code: import Menu from '@material-ui/core/Menu'; import { createStyles, withStyles, Theme } from '@material-ui/core/styles'; const myMenu = withStyles( ( theme: The ...

typescriptmaterial-ui

Struggling with integrating Axios with Vue3

Can someone assist me in figuring out what is going wrong with my Axios and Vue3 implementation? The code I have makes an external call to retrieve the host IP Address of the machine it's running on... <template> <div id="app"> ...

typescriptaxiosvuejs3

Create Functions to Encapsulate Type Guards

Is it possible to contain a type guard within a function as shown below? function assertArray(value: any): void { if (!Array.isArray(value)) { throw "Not an array" } } // This doesn't work function example1(value: string | []) { a ...

typescript

Is it possible to verify type equality in Typescript?

If the types do not match, I want to receive an error. Here is an example of an object: const ACTIVITY_ATTRIBUTES = { onsite: { id: "applied", .... }, online: { id: "applied_online", .... }, ... } as co ...

typescript

There are no call signatures available for the unspecified type when attempting to extract callable keys from a union

When attempting to write a legacy function within our codebase that invokes methods on certain objects while also handling errors, I encountered difficulty involving the accuracy of the return type. The existing solution outlined below is effective at cons ...

typescripttypescript-generics

Creating an Observable from static data in Angular that resembles an HTTP request

I have a service with the following method: export class TestModelService { public testModel: TestModel; constructor( @Inject(Http) public http: Http) { } public fetchModel(uuid: string = undefined): Observable<string> { i ...

typescriptpromiseangularobservablerxjs

Incorporating regular expressions to extract a specific string from a URL is a requirement

Can anyone assist with extracting a specific string using regex in TypeScript? I have the following URL: https://test.io/content/storage/id/urn:aaid:sc:US:8eda16d4-baba-4c90-84ca-0f4c215358a1;revision=0?component_id=e62a5567-066d-452a-b147-19d909396132 I ...

javascriptregextypescript

Tips for effectively managing 404 errors in Angular 10 with modular routing

I'm facing challenges with handling 404 pages within an Angular 10 application that utilizes modular routing architecture. Here is the structure of my code: |> app |-- app.module.ts |-- app-routing.module.ts |-- app.component{ts, spec.ts, scss, ht ...

javascriptangulartypescriptangular-router

Is there a way to get this reducer function to work within a TypeScript class?

For the first advent of code challenge this year, I decided to experiment with reducers. The following code worked perfectly: export default class CalorieCounter { public static calculateMaxInventoryValue(elfInventories: number[][]): number { const s ...

javascripttypescriptreduce

Angular D3 - The method 'getBoundingClientRect' is not present in the 'Window' type

Check out this StackBlitz demo I created: https://stackblitz.com/edit/ng-tootltip-ocdngb?file=src/app/bar-chart.ts In my Angular app, I have integrated a D3 chart. The bars on the chart display tooltips when hovered over. However, on smaller screens, th ...

angulartypescriptd3.js