@atscript/moost-validator

Drop‑in atscript validation for Moost. This package adds a tiny pipe and an interceptor that let you validate any handler argument, DTO, or DI‑injected value that comes from an @mongo.collection / .as model – no extra boilerplate, no manual validate() calls.

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Features

- 🛂 Automatic validation – if the parameter type has a validator() factory, we run it.
- ⚡ Fast & sync – validation happens in the VALIDATE pipeline stage before business logic.
- 🛠️ Composable – use as a decorator (@UseValidatorPipe) or apply globally.
- 🧩 Nice errors out of the box – interceptor converts ValidatorError → HttpError(400).

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Installation

``bash
npm i @atscript/moost-validator


Or


pnpm add @atscript/moost-validator
`

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Quick start

$3

#### a) Globally – affects every parameter/property

`ts
import { Moost } from 'moost'
import { validatorPipe } from '@atscript/moost-validator'

const app = new Moost()
app.applyGlobalPipes(validatorPipe())
`

#### b) Per controller / handler

`ts
import { Controller, Pipe } from 'moost'
import { Post, Body } from '@moostjs/event-http'
import { UseValidatorPipe } from '@atscript/moost-validator'
import { CreateUserDto } from './user.dto.as'

@UseValidatorPipe() // controller‑wide
@Controller('users')
export class UsersController {
@Post()
@UseValidatorPipe() // or per‑method
async create(@Body() dto: CreateUserDto) {}
}
`

$3

Global:

`ts
import { validationErrorTransform } from '@atscript/moost-validator'

app.applyGlobalInterceptors(validationErrorTransform())
`

Per handler:

`ts
import { UseValidationErrorTransform } from '@atscript/moost-validator'

@Post()
@UseValidationErrorTransform()
async create(@Body() dto: CreateUserDto) {}
`

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API reference

| Export | Type | Description |
| ------------------------------- | --------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| validatorPipe(opts?) | PipeFn | Low‑level factory. Returns a pipe that runs type.validator(opts).validate(value) on the argument if the type was produced by atscript. Registered with priority VALIDATE. |
| UseValidatorPipe(opts?) | Decorator | Sugar over validatorPipe. Apply to a class, method, parameter, or property. |
| validationErrorTransform() | InterceptorFn | Catches ValidatorError, wraps it into HttpError(400) with { message, statusCode, _body }. Priority CATCH_ERROR. |
| UseValidationErrorTransform() | Decorator | Sugar over validationErrorTransform(). |

$3

Any options accepted by atscript.validator(opts). E.g. { abortEarly: false }.

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How it works (under the hood)

1. Pipe checks metadata that Moost attaches to every parameter/property.
2. If the declared type has a validator() factory (i.e. it was generated from
.as file with atscript), the pipe instantiates the validator once and
runs validate(value).
3. On failure the validator throws ValidatorError.
4. Interceptor catches that error and converts it to a standard Moost
HttpError so your REST adapter sends a clean 400 Bad Request` body.

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License

MIT © 2025 Artem Maltsev