Conditional Fields

ResourcesJS includes Laravel-inspired helpers for removing fields cleanly.

when()

when() includes a value only when the condition is truthy.

class UserResource extends Resource<User> {
  toArray() {
    return {
      id: this.resource.id,
      email: this.when(currentUser.isAdmin, this.resource.email),
    };
  }
}

When the condition fails, email is removed from the final output.

Lazy Values

Pass a function to avoid computing expensive values unless the condition passes.

permissions: this.when(isAdmin, () => loadPermissions(this.resource))

unless()

unless() is the inverse of when().

email: this.unless(currentUser.isGuest, this.resource.email)

mergeWhen()

Use mergeWhen() with object spread to include multiple fields at once.

return {
  id: this.resource.id,
  ...this.mergeWhen(currentUser.isAdmin, {
    email: this.resource.email,
    permissions: this.resource.permissions,
  }),
};

Type Inference

Conditional fields are represented as optional properties in InferResource.

type UserResponse = InferResource<typeof UserResource>;
// { id: number; email?: string }

Missing values are removed recursively from nested objects and arrays.