Nest: Typed @Query Decorator

[scokmen]

I'm submitting a...

[ ] Regression
[ ] Bug report
[x] Feature request
[ ] Documentation issue or request

Current Behavior

@Query() decorator is working perfectly in most cases but when we need to cast the value of the query to Number, Boolean or Array types we must write code for that over and over again. I think we can develop some reusable decorators for that.

Suggested Method

Additional @Query() decorators.

• BooleanQuery(param?: string)
• NumericQuery(param?: string)
• ArrayQuery(param?: string, separator?: string)

If this is ok for NestJs project, I can contribute :)

Thank you.

[SeWaS]

I like the idea of having the @Query() decorator type-aware! So far I tackled this problem by using a pipe that checks and transforms the query parameter into the desired type.
Personally, I think it would be great to have such a feature in the framework.

[iagolaguna]

To complement this feature when using @Query() with an object, something like:

@Query() foo:Bar

export class Bar {
foo: string;
bar: number;
}

maybe if we use class-transformer to do that would be great too and turn this in something like

export class Bar {
@Type(() => String)
foo: string;
@Type(() => Number)
bar:number;
}

I had a similar issue if @Query() because don't parse values and now i'm using plainToClass function from class-transformer

[kamilmysliwiec]

I don't think we should add more decorators (to don't confuse new users and don't overcomplicate the basic features). However, we should automatically cast @Query('PROPERTY_NAME') and @Param('PROPERTY_NAME') to inferred types (either boolean or number) when the transform in the ValidationPipe is set to true (https://docs.nestjs.com/techniques/validation#transform-payload-objects). Since this is a breaking change, it will be added in the next major release (7.0.0) - PR is merged already https://github.com/nestjs/nest/pull/4110. In addition, we should add ParseBoolPipe and ParseArrayPipe to cover other scenarios (parsing array or explicitly parsing boolean values) - this PR is merged as well https://github.com/nestjs/nest/pull/4113 (and will be published as part of 7.0.0 release).

[SeWaS]

Ah, very nice! I didn't see that these PRs already exist. I think with these transforming pipes (and even some more) it will be a lot easier to work with proper types for (query-) parameters.
Really like this solution and I'm looking forward to 7.0.0 then 👍