Builder

A simple Typescript builder pattern for your project

Usage

import { build } from '@stewartmcgown/ts-builder';

class Cthulu {
    dread: boolean;
    stats: {
        cultists: number;
        kills: number;
    }
}

const cthulu = build(Cthulu)
    .dread(true)
    .stats(b => b
        .cultists(1000)
        .kills(1000000)
    )
    .$build()

// console.log(cthulu)

[class Cthulu] {
    dread: true,
    stats: {
        cultists: 1000,
        kills: 1000000
    }
}

Nested Objects

You can either build nested objects using a builder, or by passing in an object.

const cthulu = build(Cthulu)
    .dread(true)
    .stats({
        cultists: 1000,
        kills: 1000000
    })
    .$build()

Interfaces

interface Shadow {
    innsmouth: Date;
    water: boolean;
}

const obj = build<Shadow>()
    .innsmouth(new Date())
    .water(() => !!checkWaterIsWet()) // Use functions to set plain values
    .$build();

Auto Class Hydration

ts-builder can detect if you are using a class meta framework, like @nestjs/graphql, and will hydrate entities it meets with the builder automatically.

@ObjectType()
export class A {
    @Field()
    b: B
}

@ObjectType()
export class B {
    @Field()
    c: string

    @Field()
    d: D
}

@ObjectType()
export class D {
    @Field()
    e: string
}

const a = build(A) // No additional config required
    .b(b => b
        .c('Hello World')
        .d(d => d
            .e('Hello World')
        )
    )
    .$build();

a.b.constructor === B // ✅ 
a.b.d.constructor === D // ✅ 

If you are using a

API

$build

Builds the object and returns it.

$set

Sets a property on the object.

build(Cthulu)
    .$set('dread', false) // It's his day off
    
    .$build();

You may also shallow merge objects using $set. Uses Object.assign.

build(Cthulu)
    .$set({
        stats: {
            cultists: 1000,
            kills: 1000000
        }
    })

⚠️ Function Props

If you are using a function prop, you must use $set to set it. This is because the builder needs to know that you are setting a function, and not a builder.

class Service {
    getSomething: () => Promise<string>;
}

// This will not work the way you want it to
❌ build(Service)
    .getSomething(() => fetch('...')) 

// This will work
✅ build(Service)
    .$set('getSomething', () => fetch('...')) 

// This will also work, but looks a touch ugly
✅ build(Service) 
    .getSomething(() => () => fetch('...'))