Overview

Schema-based validation using Standard Schema specification

Overview

rich-domain provides built-in validation support using the Standard Schema specification. This means you can use your favorite validation library - Zod, Valibot, ArkType, or any other Standard Schema-compatible library.

import { z } from "zod";

const userSchema = z.object({
  id: z.custom<Id>((val) => val instanceof Id),
  name: z.string().min(2),
  email: z.string().email(),
  age: z.number().min(0).max(150),
});

class User extends Aggregate<UserProps> {
  protected static validation = {
    schema: userSchema,
    config: {
      onCreate: true,
      onUpdate: true,
      throwOnError: true,
    },
  };
}

Why Standard Schema?

Library Agnostic

Use Zod, Valibot, ArkType, or any Standard Schema-compatible library

Type Inference

Get full TypeScript inference from your schemas

Validation Timing

Control when validation runs (create, update, or both)

Error Handling

Choose between throwing errors or collecting them

Supported Libraries

Any library implementing the Standard Schema spec works:

Zod

import { z } from "zod";

const schema = z.object({
name: z.string().min(2),
email: z.string().email(),
});

Basic Usage

1. Define Your Schema

import { z } from "zod";
import { Id } from "@woltz/rich-domain";

const productSchema = z.object({
  id: z.custom<Id>((val) => val instanceof Id),
  name: z.string().min(1, "Name is required"),
  price: z.number().positive("Price must be positive"),
  stock: z.number().int().min(0, "Stock cannot be negative"),
  status: z.enum(["draft", "published", "archived"]),
});

type ProductProps = z.infer<typeof productSchema>;

2. Apply to Entity/Aggregate

import { Aggregate, EntityValidation } from "@woltz/rich-domain";

class Product extends Aggregate<ProductProps> {
  protected static validation: EntityValidation<ProductProps> = {
    schema: productSchema,
    config: {
      onCreate: true, // Validate on construction
      onUpdate: true, // Validate on property changes
      throwOnError: true, // Throw ValidationError on failure
    },
  };

  get name() {
    return this.props.name;
  }
  set name(value: string) {
    this.props.name = value;
  }

  get price() {
    return this.props.price;
  }
  set price(value: number) {
    this.props.price = value;
  }
}

3. Validation in Action

// Valid - no error
const product = new Product({
  name: "Widget",
  price: 29.99,
  stock: 100,
  status: "draft",
});

// Invalid - throws ValidationError
const invalid = new Product({
  name: "", // ❌ Name is required
  price: -10, // ❌ Price must be positive
  stock: 5.5, // ❌ Stock must be integer
  status: "draft",
});

Validation Configuration

interface ValidationConfig {
  onCreate?: boolean; // Validate in constructor (default: true)
  onUpdate?: boolean; // Validate on property changes (default: true)
  throwOnError?: boolean; // Throw or collect errors (default: true)
}

onCreate

When true, validates the entire entity when constructed:

class Product extends Aggregate<ProductProps> {
  protected static validation = {
    schema: productSchema,
    config: { onCreate: true },
  };
}

// Validation runs here
const product = new Product({ name: "", price: -1 });
// ValidationError: Name is required, Price must be positive

onUpdate

When true, validates after every property change:

class Product extends Aggregate<ProductProps> {
  protected static validation = {
    schema: productSchema,
    config: { onUpdate: true },
  };

  set price(value: number) {
    this.props.price = value;
    // Validation runs automatically after this
  }
}

const product = new Product({ name: "Widget", price: 29.99, ... });
product.price = -10; // ValidationError: Price must be positive

throwOnError

Controls error handling behavior:

// throwOnError: true (default)
// Throws ValidationError immediately

// throwOnError: false
// Stores errors internally, doesn't throw

Validation for Value Objects

Value Objects also support validation:

import { ValueObject } from "@woltz/rich-domain";

const emailSchema = z.string().email("Invalid email format");

class Email extends ValueObject<string> {
  protected static validation = {
    schema: emailSchema,
    config: { onCreate: true, throwOnError: true },
  };

  getDomain(): string {
    return this.value.split("@")[1];
  }
}

// Valid
const email = new Email("[e-mail]");

// Invalid - throws
const invalid = new Email("not-an-email");
// ValidationError: Invalid email format

Non-Throwing Mode

Collect errors without throwing:

class ProductSafe extends Aggregate<ProductProps> {
  protected static validation = {
    schema: productSchema,
    config: {
      onCreate: true,
      throwOnError: false, // Don't throw
    },
  };
}

const product = new ProductSafe({
  name: "",
  price: -10,
  stock: 100,
  status: "draft",
});

// Entity is created, but has errors
if (product.hasValidationErrors) {
  console.log(product.validationErrors?.getMessages());
  // ["Name is required", "Price must be positive"]
}

ValidationError

The ValidationError class provides rich error information:

try {
  const product = new Product({ name: "", price: -10, ... });
} catch (error) {
  if (ValidationError.isValidationError(error)) {
    // Get all error messages
    error.getMessages();
    // ["Name is required", "Price must be positive"]

    // Get errors for specific field
    error.getErrorsForPath("price");
    // [{ path: ["price"], message: "Price must be positive" }]

    // Check if specific field has errors
    error.hasErrorsForPath("name"); // true

    // Access raw issues
    error.issues;
    // [
    //   { path: ["name"], message: "Name is required" },
    //   { path: ["price"], message: "Price must be positive" }
    // ]

    // Serialize for API response
    error.toJSON();
    // { name: "ValidationError", message: "...", issues: [...] }
  }
}

Complete Example

import { z } from "zod";
import {
  Id,
  Aggregate,
  EntityValidation,
  EntityHooks,
  ValidationError,
} from "@woltz/rich-domain";

// Schema
const orderSchema = z.object({
  id: z.custom<Id>((val) => val instanceof Id),
  customerId: z.string().uuid(),
  items: z
    .array(
      z.object({
        productId: z.string().uuid(),
        quantity: z.number().int().positive(),
        unitPrice: z.number().positive(),
      })
    )
    .min(1, "Order must have at least one item"),
  status: z.enum(["draft", "confirmed", "shipped", "delivered"]),
  total: z.number().min(0),
});

type OrderProps = z.infer<typeof orderSchema>;

class Order extends Aggregate<OrderProps> {
  protected static validation: EntityValidation<OrderProps> = {
    schema: orderSchema,
    config: {
      onCreate: true,
      onUpdate: true,
      throwOnError: true,
    },
  };

  get items() {
    return this.props.items;
  }
  get total() {
    return this.props.total;
  }
  get status() {
    return this.props.status;
  }

  addItem(productId: string, quantity: number, unitPrice: number) {
    this.props.items.push({ productId, quantity, unitPrice });
    this.recalculateTotal();
  }

  private recalculateTotal() {
    this.props.total = this.props.items.reduce(
      (sum, item) => sum + item.quantity * item.unitPrice,
      0
    );
  }

  confirm() {
    if (this.props.items.length === 0) {
      throw new Error("Cannot confirm empty order");
    }
    this.props.status = "confirmed";
  }
}

// Usage
try {
  const order = new Order({
    customerId: "123e4567-e89b-12d3-a456-426614174000",
    items: [], // ❌ Empty - will fail validation
    status: "draft",
    total: 0,
  });
} catch (error) {
  if (ValidationError.isValidationError(error)) {
    console.log(error.getMessages());
    // ["Order must have at least one item"]
  }
}

Next Steps

Hooks

Lifecycle hooks for custom validation rules

Error Handling

Working with ValidationError and error responses