Add new mapped-type for intersection more than two classes

[trycontrolmymind]

I'm submitting a...

[ ] Regression 
[ ] Bug report
[x] Feature request
[ ] Documentation issue or request
[ ] Support request => Please do not submit support request here, instead post your question on Stack Overflow.

Current behavior

import { IntersectionType } from '@nestjs/mapped-types';
import { BaseTemplateFiltering } from 'validators/BaseTemplateFiltering';
import { LimitOffsetQuery } from 'validators/LimitOffsetQuery';
import { SortByQuery } from 'validators/SortByQuery';

export class BaseTemplateQueryDto extends IntersectionType(
  BaseTemplateFiltering,
  IntersectionType(LimitOffsetQuery, SortByQuery),
) {}

Wanted behavior

import { IntersectionMultipleType } from '@nestjs/mapped-types';
import { BaseTemplateFiltering } from 'validators/BaseTemplateFiltering';
import { LimitOffsetQuery } from 'validators/LimitOffsetQuery';
import { SortByQuery } from 'validators/SortByQuery';

export class BaseTemplateQueryDto extends IntersectionMultipleType(
  BaseTemplateFiltering,
  LimitOffsetQuery, 
  SortByQuery,
) {}

I don't think is it possible to do things such this...

[jmcdo29]

Might be a bit ugly, but as these types are composable you could do something like

const BasetemplateQueryDto extends IntersectionType(
	IntersectionType(
		BaseTemplateFiltering,
		LimitOffsetQuery
	),
	SortByQuery
) {}

Just a thought until there's an official verdict on this. Don't immediately know what would happen to duplicate keys, what kind of precedence would take, so be wary of that.

[kamilmysliwiec]

Would you like to create a PR for this issue? We can let `IntersectionType accept a spread arg (infinite number of args) and just combine them all.

[trycontrolmymind]

Would you like to create a PR for this issue? We can let `IntersectionType accept a spread arg (infinite number of args) and just combine them all.

Okay, i'll try ​this week

[altick]

A bit off-topic question, but why is this function called intersection when it actually gives a union of the given types? Personally I understand the intersection as something that exists in all given places 🤔

[trycontrolmymind]

@altick Yep it was a bit stange for me tooo

intersection should be something like this, but now it's work as union

[kamilmysliwiec]

@trycontrolmymind @altick check out this link https://www.reddit.com/r/typescript/comments/9qduq3/why_is_type_intersection_called_like_that_its/ to learn more on why we (and TypeScript itself) use Intersection/Union names here.

Let's track this here #341

[trycontrolmymind]

Could someone review PR #341 with new functionality, after that I could edit documentation after review.