NestJS TypeORM Validator


Lightweight NestJS decorators for validating values against TypeORM entities.

This package provides several decorators (more to come):

| Decorator | Description |
| ----------- | ------------------------------------------------------------- |
| @ExistsIn | Ensures a value exists in a specified entity/table column. |
| @UniqueIn | Ensures a value is unique in a specified entity/table column. |

It integrates with TypeORM DataSource instances, enabling database-aware validation in DTOs.

---

Key features

- Works with TypeORM entity classes or table name strings.
- Supports multiple (named) TypeORM DataSource registrations.
- Supports class-validator options (for example each for array validation, or message for custom message).
- Minimal runtime dependency surface — relies on TypeORM and class-validator as peer dependencies.

---

Installation

Install the package:

$3

``bash
npm install @rotyro-tools/nestjs-typeorm-validator
`

$3

`bash
yarn add @rotyro-tools/nestjs-typeorm-validator
`

$3

`bash
pnpm add @rotyro-tools/nestjs-typeorm-validator
`

$3

`bash
bun add @rotyro-tools/nestjs-typeorm-validator
`

---

Peer dependencies

This package declares the following peer dependencies that consumers must install at compatible versions:

- class-validator
- typeorm

Install them:

$3

`bash
npm install --save class-validator typeorm
`

$3

`bash
yarn add class-validator typeorm
`

$3

`bash
pnpm add class-validator typeorm
`

$3

`bash
bun add class-validator typeorm
`

---

Getting started

1. Register one or more TypeORM DataSources to be used by the validators:

`typescript
import { registerDataSourceForValidation } from '@rotyro-tools/nestjs-typeorm-validator';
import { DataSource } from 'typeorm';

const dataSource = new DataSource({
type: 'mysql',
host: 'localhost',
port: 3306,
username: 'user',
password: 'pass',
database: 'db',
entities: [
/ ... /
],
synchronize: false,
});

// If you initialize the DataSource yourself, that's fine. If you don't, registerDataSourceForValidation will attempt to initialize it for you.
await dataSource.initialize();

// Register your DataSource
registerDataSourceForValidation(dataSource); // Registers as 'default'

// Second 'replica' DataSource
const replicaDataSource = new DataSource({
type: 'mysql',
host: 'replica-host',
port: 3306,
username: 'replica_user',
password: 'replica_pass',
database: 'db_replica',
entities: [
/ ... /
],
synchronize: false,
});

// Optionally initialize the replica DataSource as well
await replicaDataSource.initialize();

// Register your DataSource
registerDataSourceForValidation(replicaDataSource, 'replica');
`

2. Use decorators in your DTOs:

`typescript
import { ExistsIn, UniqueIn } from '@rotyro-tools/nestjs-typeorm-validator';

import { User } from '@/modules/users/entities/user.entity';

class CreatePostDto {
// Ensure the given authorId exists in the User entity's id column
// in the 'default' DataSource
@ExistsIn(User, 'id', null, { message: 'Author not found' })
authorId: number;

// Ensure the title is unique in the posts table (using a table name)
// in the 'replica' DataSource
@UniqueIn('post', 'title', 'replica', { message: 'Title already taken' })
title: string;
}
`

---

Examples

Checking existence (minimal setup):

`typescript
import { ExistsIn } from '@rotyro-tools/nestjs-typeorm-validator';

class CreateCommentDto {
@ExistsIn('user', 'id')
userId: number;
}
`

Unique constraint (entity usage and custom message):

`typescript
import { UniqueIn } from '@rotyro-tools/nestjs-typeorm-validator';

import { User } from '@/modules/users/entities/user.entity';

class RegisterUserDto {
@UniqueIn(User, 'email', null, { message: 'Email already in use' })
email: string;
}
`

Validating arrays:

`typescript
import { ExistsIn } from '@rotyro-tools/nestjs-typeorm-validator';

class BulkCreateDto {
@ExistsIn('tag', 'name', 'replica', {
each: true,
message: 'Tag does not exist',
})
tagNames: string[];
}
`

---

Development

Install dependencies:

`bash
npm install
`

Build:

`bash
npm run build
`

Lint:

`bash
npm run lint
`

Format:

`bash
npm run format
`

Run tests:

`bash
npm run test
`

Commit (with Commitizen):

`bash
npm run cm
``