collectype / factory/objects/objectKey / objectKeyFactory
objectKeyFactory<
T,C>(ctx,oper): <K>(field,target) =>C
Defined in: factory/objects/objectKey.ts:39
Creates a predicate filter for object key presence using PredicType.object.key.
T
The item type in the collection.
C extends Wherable<T, C>
The Wherable context type (must extend Wherable<T, C>).
C
The context (usually a collection) supporting the where method.
ObjectKeyOper
The object key operation (e.g., ‘containsKey’, ‘lacksKey’, etc.).
A function that takes a field (of type object on T) and a target key, and applies the object key predicate to filter the context.
<
K>(field,target):C
K extends string | number | symbol
K
string |
symbol |
C
// Example: Composing an object key filter as a property, homogeneous model
import { BaseFunctions } from 'collectype';
import { objectKeyFactory } from 'collectype';
type Person = { name: string; meta: { country: string; city: string } };
class PersonFunctions extends BaseFunctions<Person> {
objectContainsKey = objectKeyFactory<Person, this>(this, 'containsKey');
}
// Usage:
const people: Person[] = [
{ name: 'Alice', meta: { country: 'FR', city: 'Paris' } },
{ name: 'Bob', meta: { country: 'US' } }
];
const fn = new PersonFunctions(people);
const filtered = fn.objectContainsKey('meta', 'city');
// filtered contains the items where 'meta' has the key 'city'