Restrict the properties of an object to match the properties of a different object

Question

Restrict the properties of an object to match the properties of a different object

I am currently developing an Object patching utility function with the following code snippet

class Test{
  a:number;
  b:number;
}

var c:Test={a:0,b:1}

function patchable<T>(obj:T){
  return {
    patch:function<K>(prop:K){
      return patchable({...obj,...prop})},
    value:function():T{return obj}
		}
}

c=patchable(c).patch({notAllow:94}).value()

Is it feasible in typescript to restrict the patch function to only accept objects containing properties that are present in the Test interface, meaning K can exclusively have keys available in T

typescript

Answer 1

Answer №1

class Sample {
  x: number
  y: number
}

var z: Sample = {
  x: 0,
  y: 1
}

function adaptable<U>(customObj: U) {
  return {
    modify: function <V extends keyof U>(property: Pick<U, V>) {
      return adaptable({ ...customObj, ...property })
    },
    result: function(): U {
      return customObj
    }
  }
}

z = adaptable(z).modify({ disallow: 94 }).result() // fails
z = adaptable(z).modify({ x: 94 }).result() // compiles

Answer 2

class Sample {
  x: number
  y: number
}

var z: Sample = {
  x: 0,
  y: 1
}

function adaptable<U>(customObj: U) {
  return {
    modify: function <V extends keyof U>(property: Pick<U, V>) {
      return adaptable({ ...customObj, ...property })
    },
    result: function(): U {
      return customObj
    }
  }
}

z = adaptable(z).modify({ disallow: 94 }).result() // fails
z = adaptable(z).modify({ x: 94 }).result() // compiles

Answer 3

Answer №2

Another approach is to use the Partial method:

class Example {
  x?: number
  y?: number
}

var z: Example = {
  x: 0,
  y: 1
}
function editable<E>(object: E) {
  return {
    edit: function (property: Partial<E>) {
      return editable({ ...object, ...property })
    },
    showValue: function(): E {
      return object
    }
  }
}

z = editable(z).edit({ notAllowed: 94 }).showValue() // fails
z = editable(z).edit({ x: 94 }).showValue() // works
console.log(z)

Answer 4

Another approach is to use the Partial method:

class Example {
  x?: number
  y?: number
}

var z: Example = {
  x: 0,
  y: 1
}
function editable<E>(object: E) {
  return {
    edit: function (property: Partial<E>) {
      return editable({ ...object, ...property })
    },
    showValue: function(): E {
      return object
    }
  }
}

z = editable(z).edit({ notAllowed: 94 }).showValue() // fails
z = editable(z).edit({ x: 94 }).showValue() // works
console.log(z)

Restrict the properties of an object to match the properties of a different object

Answer №1

Answer №2

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