根据其他接口的属性创建接口

Question

I have two interfaces, Workflow and WorkflowVersion

workflow.model.ts

import { WorkflowVersion } from './workflow-version.model';

export interface Workflow{
    name: string;
    ID: number;
    workflowVersions: WorkflowVersion[];
}

workflow-version.model.ts

export interface WorkflowVersion{
    versionID: number;
    lastPublished: string;
    environmentID: number;
}

I'd like to create an interface that 'flattens' the two. This new interface, WorkflowFlat , should contain all non-object type properties of both interfaces. Currently I have this:

workflow-flat.model.ts

export interface WorkflowFlat {
    name: string;
    ID: number;
    versionID: number;
    lastPublished: string;
    environmentID: number;
}

The model above achieves this, but it feels repetitive. If I want to add a description property to WorkflowVersion down the road, I'd have to remember to also add it to WorkflowFlat . Is there any way to make the model automatically take all properties from the two interfaces and then create a new interface with the non-object ones?

Answer 1

Aaron Beall's answer is close (sorry I can't comment yet), but it doesn't properly remove all the keys that extends object , so they'll be required by the final type as key: never which is not wanted.

The following snippet achieves the objective by reusing a type-level helper from the awesome tycho01/typical repo :

export type NonMatchingPropNames<T, X> = { [K in keyof T]: T[K] extends X ? never : K }[keyof T];

export type NonMatchingProps<T, X> = Pick<T, NonMatchingPropNames<T, X>>;

type PrimitiveValuesOf<T> = NonMatchingProps<T, object>;

type A = PrimitiveValuesOf<Workflow & WorkflowVersion>;

const a: A = {
  name: '',
  ID: 0,
  versionID: 1,
  lastPublished: '',
  environmentID: 2
}; // OK