Add decorator to allow specification of the schema type name

[radacovsky]

You can use @ApiSchema to set a custom schema name.
Custom schema names are not inherited.

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[x] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Other... Please describe:

What is the current behavior?

Currently when creating schema for a class the class name is taken as the schema name.

Issue Number: N/A

What is the new behavior?

A new decorator has been introduced: @ApiSchema. Using this decorator you can define custom schema name different from the class name.

e.g.
@ApiSchema({name: 'User'})
class UserDto {}

will produce a schema with name User, not UserDto.

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

[kamilmysliwiec]

Thanks! Could you create a PR to the docs as well? https://github.com/nestjs/docs.nestjs.com

[radacovsky]

Ok, will do!

[radacovsky]

@kamilmysliwiec here is the PR for documentation update
nestjs/docs.nestjs.com#1533

[nartc]

LGTM

[nartc]

Have a question on the docs PR.

[radacovsky]

@nartc I haven't noticed any question there. Can you link it here, please?

[andrew-itscript]

When do you plan to merge and release it ?

[anchan828]

I can't wait for merge and release it!

[Dhiraj-JC]

This PR is very helpful. When you guys are plan to merge and release it?

[zroadhouse-rigup]

Can we release this soon please? It's been ready for quite a while now. There are other useful features that can be built on top of the ApiSchema decorator once this is merged (documentation at the type level).

[adworacz]

It looks like this branch has merge conflicts - is this all that remains to be fixed? I'm willing to assist to help get this merged.

[radacovsky]

@adworacz I doubt the maintainer of this project wants to merge this PR/functionality. If he wanted he would have merged it when it was all green.

[kamilmysliwiec]

Ignore merge conflicts, I'll resolve them when I get to this PR.

[kamilmysliwiec]

#2427