Function leftJoinHeterogeneous

Performs a left outer join on two heterogeneous sequences.

Example

type Person = { name: string };
type Pet = { name: string; owner: Person };

const magnus: Person = { name: 'Magnus' };
const terry: Person = { name: 'Terry' };
const adam: Person = { name: 'Adam' };
const john: Person = { name: 'John' };

const barley: Pet = { name: 'Barley', owner: terry };
const boots: Pet = { name: 'Boots', owner: terry };
const whiskers: Pet = { name: 'Whiskers', owner: adam };
const daisy: Pet = { name: 'Daisy', owner: magnus };
const scratchy: Pet = { name: 'Scratchy', owner: { name: 'Bob' } };

const people = from([magnus, terry, adam, john]);
const pets = from([barley, boots, whiskers, daisy, scratchy]);

const result = leftJoinHeterogeneous<Pet, Person, { ownerName: string; pet: string | null }>(
    people,
    pets,
    person => person,
    pet => pet.owner,
    person => ({ ownerName: person.name, pet: null }),
    (person, pet) => ({ ownerName: person.name, pet: pet.name })
  )
  .toArray();

expect(result).toEqual([
  { ownerName: 'Magnus', pet: 'Daisy' },
  { ownerName: 'Terry', pet: 'Barley' },
  { ownerName: 'Terry', pet: 'Boots' },
  { ownerName: 'Adam', pet: 'Whiskers' },
  { ownerName: 'John', pet: null }
]);

Typeparam

TFirst The type of elements in the first sequence.

Typeparam

TSecond The type of elements in the second sequence.

Typeparam

TKey The type of the key returned by the key selector functions.

Typeparam

TResult The type of the result elements.

Returns

A sequence containing results projected from a left outer join of the two input sequences.