Validation on parent DTO instead

[meager condor]

class Datetime {
  @ApiProperty({
    type: Date,
    default: new Date(),
  })
  @IsDate()
  datetime: Date;
}
export class MainDto {
  @ApiProperty({ type: Datetime })
  @ValidateNested()
  @Type(() => Date)
  datetime: Datetime
}

Why is it that when I put @IsDate() in MainDto it works, but when I put @IsDate() in Datetime it doesn't work? I want to do my validation on "child dto", I thought @ValidationNested() would run the validation on the child, and report error if any of the validation fails

[humble tundra]

What's the request body look like?

[meager condor]

also I don't understand why setting

@Type(() => Datetime)

would produce this error: nested property datetime must be either object or array

[meager condor]

URL?datetime=2023-11-07T17:07:05.652Z

[humble tundra]

Why are you trying to set up a nested object when you aren't sending an object

[meager condor]

so I should just set the validator in MainDto and remove Datetime?

[humble tundra]

Yes

I don't know why you were trying to make a nested object there to begin with

[meager condor]

export class MainDto {
  @Type(() => Boolean)
  @IsBoolean()
  arriveBy: boolean
}

what about boolean? I want to validate true/false but any value would become true

can I check for boolean in Query? Or is it not possible because they are plain text

[humble tundra]

@Transform(({ val }) => JSON.parse(val))

[meager condor]

do I still need @Type with this?

[humble tundra]

Nope

[meager condor]

if I input anything other than true/false, it throws error in Nest, and it couldn't trigger the @IsBoolean check

[humble tundra]

Correct

[meager condor]

is there any way to "catch" it and pass it to the @IsBoolean check?

basically throw @IsBoolean and respond with arriveBy must be a Boolean

[humble tundra]

You could returnval === 'true' instead of JSON.parse(val)

Boolean doesn't work because it returns the truthy value of whatever you pass to it. And, confusingly enough, !!'false' evaluates to true

[meager condor]

hmm I see, guess using boolean check here is kinda a bad idea

[humble tundra]

There is @IsBooleanString()

[meager condor]

is there a way to use this to check the string before the @Transform happens?

putting it before @Transform with JSON.parse still gives error

[humble tundra]

Transform happens before validation. Always

[meager condor]

hmm okay, then I think val === 'true' is my best bet

I have another Coordinate which uses nested object as I will be reusing the Coordinate

class Coordinate {
  @IsNumber()
  @Type(() => Number)
  @Min(-90)
  @Max(90)
  lat: number;

  @IsNumber()
  @Type(() => Number)
  @Min(-180)
  @Max(180)
  lon: number;
}

class From {
  @ValidateNested()
  @Type(() => Coordinate)
  from_lat: Coordinate["lat"];

  @ValidateNested()
  @Type(() => Coordinate)
  from_lon: Coordinate["lon"];
}

// class To with same layout...

export class MainDto {
  @ValidateNested()
  @Type(() => From)
  from: From;
}

This does not trigger any validation as I can put anything in from_lat or from_lon. How should I solve this?

[humble tundra]

How do you send these values?

[meager condor]

?from_lat=test&from_lon=test

[humble tundra]

Then it won't be a nested object, right?

You'd need something like ?from[lat]=test&from[lon]=test

And even then, needed query parameters are not necessarily standard, so support is not guaranteed

[meager condor]

oh I think I misunderstood something then...
But is that possible to do check in Coordinate since I don't want to repeat the same code to check over and over again

[humble tundra]

Look into querystring or qs to see how things are parsed initially

[humble tundra]

You could always extend parent classes that have these fields if you really don't want to create them on each necessary query dto

[meager condor]

what I am trying to do is that:

• lat is always be -90 to 90
• lon is always be -180 to 180
  and this is always the initial validation for Coordinate, hence I want to put it in there

and then some other dto that uses Coordinate will have further restriction/check, where maybe lat would be be 0 to 30

this way, if I put the initial check in Coordinate I can use it with the extra restriction or without I believe

but right now it is not doing any validation, can you only do validation on "parent" and not "child"?

I think extending Coordinate only allows me to add extra parameters, and cannot achieve what I want. Please correct me if I am wrong

[humble tundra]

You could use PickType from @nestjs/mapped-types` for this

[humble tundra]

With PickType you can take existing fields and add extra metadata to them

[humble tundra]

By parent and child do you mean super and child classes or current and nested classes?

[meager condor]

current and nested classes

[humble tundra]

Validation will happen on what fields your decorate

[meager condor]

class Coordinate {
  @IsNumber()
  @Min(-90)
  @Max(90)
  lat: number;

  @IsNumber()
  @Min(-180)
  @Max(180)
  lon: number;
}
class From extends PickType(Coordinate, ["lat", "lon"] as const) {
  from_lat: Coordinate["lat"];
  from_lon: Coordinate["lon"];
}
class To extends PickType(Coordinate, ["lat", "lon"] as const) {
  to_lat: Coordinate["lat"];
  to_lon: Coordinate["lon"];
}
class MainDto {
  from: From;
  to: To;
}

This would produce the image below in Swagger, how can I change it so there are only from_lat, from_lon, to_lat, to_lon in the request? And it is not doing the Min Max check in Coordinate too. I'm definitely doing something wrong but I don't quite understand

for example, in class From, I want to input the lat and lon with key from_lat and from_lon, but still keep the validation check in Coordinate

Validation on parent DTO instead

[humble tundra]

Okay, seriously, why not just set these fields directly? This seems like a lot of work for no payout to be completely honest

[meager condor]

Coordinate will be reused very often in the future, so I try to make it into a dto for basic validation.
And then there would be more validation based on what kind of data I am trying to get as they require a specific range of Coordinate. That is my idea on why I should create the Coordinate dto.

In this case right now, I have two set of Coordinate which I would like to transfer, hence I made From and To to “prefix” the lat and lon

If I do this:

class MainDto {
from: Coordinate;
to: Coordinate;
}

It would result in duplicated key and I cannot set two Coordinate

(Sorry I cant use codeblock on phone for some reason)

Or is there a decorator to change the key name of lat/lon so I can just do “from: Coordinate; to: Coordinate” in MainDto instead?

[humble tundra]

Okay, let's take a step back: what do you want the eventually swagger and query to look like? Let's start with the goal and work from there

[meager condor]

can swagger have nested layout?

[humble tundra]

What do you mean by that?

[meager condor]

like you see here

I have from_lat and from_lon

can I make it so it says:

from: {
    lat: ____
    lon: ____
}

or is it not possible in Swagger with @Query?

[humble tundra]

Is that how you want the query parameters to look? from[lat]=test&from[lon]=test&to[lat]=test&to[lon]=test?

[meager condor]

actually nevermind, this will wrok: from_lat=test&from_lon&test&to_lat=test&to_lon=test

[humble tundra]

Then no, you do not want to have a nested class

You want those four properties to be on the main class, but you do not want nested classes

Guaranteed

[meager condor]

but what if I want to reuse Coordinate?

what kind if query allows me to reuse?

[humble tundra]

But this isn't a Coordinate, right? You could transform it into one, but that;s not what your query parameters are showing it to be

These are four query parameter fields, right? Not nested objects

[meager condor]

hmm I see. When should I be using nested objects?

[humble tundra]

Personally, in query parameters, never

[meager condor]

is it uncommon to use it on @Query since they are mostly plain text?

[humble tundra]

It's a non-standard thing to do. I believe querystring supports it, which is what express uses for parsing the query string, but I forget how coded into theURL Standard it is

Can you do it? Sure. Should you? That's up to you to decide in the end

[meager condor]

by transforming you mean this?

validate user input with:

class QueryDto {
    from_lat: …
    from_lon: …
    to_lat: …
    to_lon: …
    arriveBy: …
    datetime: …
}

And then whenever read it, I would create another Dto to transform from_lat from_lon into a single Coordinate, same for to_lat and to_lon?

[humble tundra]

Yes, you could do that with a pipe or inside the controller

I don't think it would be too difficult though to just make a CoordinateQueryParam class that looks something like

export class CoordinateQueryParam {
  from_lat: number;
  from_lon:  number;
  to_lat: number;
  to_lon: number;
}

And any subsequent parameters that needs to be added can be by using the mapped-types from @nestjs/swagger like

export class QueryDto extends CoordinateQueryParams {
  arriveBy: Date;
  datetime: Date;
}

[meager condor]

that’s actually a great idea

[humble tundra]

This is what I mentioned in the linked message

[meager condor]

for piping I see you put it in the controller in the tutorial, but my controller right now already contain a validation pipe for the Query

@Get()
doSomething(@Query() query: QueryDto) {}

do I use @UsePipes(new TransformationPipe(FinalDto))?

[humble tundra]

Using a pipe to transform it actually might get a little difficult as it would mess with the type metadata. Might be doable, but it might just be easier to do that in your controller

[meager condor]

I see

[meager condor]

but now that I think about it, wouldn’t that mean I have to put all the validation on CoordinateQueryParam?

oh wait, I do the basic validation on CoordinateQueryParam, and it would transform into Coordinate which would be always correct as it’s already validated on CoordinateQueryParam

[humble tundra]

Don;t you want to do that already?

[meager condor]

am I understanding correctly?

and then whenever I want more validation, I do PickType

[humble tundra]

Give it a shot and see. I might not be following your train of thought, but you might be on to something. It's been a bit of a long day

[meager condor]

yeah I shall try and work on it and see if it works. Thank you for helping me, I am new to this and you helped a lot!