Pluggable Validation

nestjs-codegen translates your @Body()/@Query() DTOs (class-validator decorators) and defineContract schemas into a neutral SchemaNode IR, then renders that IR with a validation adapter. zod, valibot, and arktype each ship as their own adapter package (none is bundled in core). Adding a new library is one render function away (the interface is shaped around Standard Schema).

Choosing an adapterCopy Anchor Link

import { defineConfig } from '@dudousxd/nestjs-codegen';
import { zodAdapter } from '@dudousxd/nestjs-codegen-zod';

export default defineConfig({
  validation: zodAdapter,
});

What gets generatedCopy Anchor Link

Given this DTO:

class CreateUserDto {
  @IsEmail() email!: string;
  @MinLength(8) password!: string;
}

each adapter renders forms.ts in its own idiom:

import { z } from 'zod';

export const CreateBodySchema = z.object({
  email: z.string().email(),
  password: z.string().min(8),
});
export type CreateBody = z.infer<typeof CreateBodySchema>;

Request types from schemasCopy Anchor Link

The adapter decides how forms.ts is written. The types of the generated client come from wherever the route declares its schema — a defineContract, or a validation pipe such as @Body(new ZodPipe(schema)) — and are inferred by the TypeScript checker through Standard Schema, so refinements, defaults and transforms resolve to real types whichever library the schema is written in. See Schema pipes.

Decorator coverageCopy Anchor Link

The class-validator → IR translator understands the common decorators: @IsString, @IsNumber/@IsInt, @IsBoolean, @IsDate, @IsEmail/@IsUrl/@IsUUID, @Matches, @MinLength/@MaxLength/@Length, @Min/@Max, @IsPositive/ @IsNegative, @IsEnum/@IsIn, @IsOptional/@IsDefined, @IsNotEmpty, @ValidateNested + @Type(() => X) (nested + arrays), @IsObject, @Allow.

Unmappable decorators are kept as a comment with a warning — the schema still compiles.

Writing your own adapterCopy Anchor Link

A ValidationAdapter renders the IR to source text:

import type { ValidationAdapter } from '@dudousxd/nestjs-codegen';

export const myAdapter: ValidationAdapter = {
  name: 'my-lib',
  importStatements: ({ used }) => (used ? ["import * as m from 'my-lib';"] : []),
  render(node, ctx) { /* SchemaNode → string */ return '…'; },
  renderModule(mod) { /* root + hoisted named schemas */ return { schemaText: '…', namedNestedSchemas: new Map(), warnings: [] }; },
  inferType: (constName) => `m.Infer<typeof ${constName}>`,
};

Pass the instance to validation and you're done.