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Step 3: Create the data structures

Inventory data lives in a module-scoped MikroORM entity. Keep multi-tenancy in mind by including both tenant_id and organization_id.

1. Define the entity​

mkdir -p packages/inventory/src/modules/inventory/data
touch packages/inventory/src/modules/inventory/data/entities.ts
touch packages/inventory/src/modules/inventory/data/validators.ts
data/entities.ts
import { Entity, Property, PrimaryKey } from '@mikro-orm/core';
import { v4 as uuid } from 'uuid';

@Entity({ tableName: 'inventory_items' })
export class InventoryItemEntity {
  @PrimaryKey({ columnType: 'uuid' })
  id = uuid();

  @Property({ columnType: 'uuid' })
  tenant_id!: string;

  @Property({ columnType: 'uuid' })
  organization_id!: string;

  @Property()
  sku!: string;

  @Property()
  name!: string;

  @Property({ columnType: 'integer' })
  quantity!: number;

  @Property({ columnType: 'text', nullable: true })
  location?: string;

  @Property({ columnType: 'timestamptz', defaultRaw: 'now()' })
  created_at: Date = new Date();

  @Property({ columnType: 'timestamptz', defaultRaw: 'now()', onUpdate: () => new Date() })
  updated_at: Date = new Date();

  @Property({ columnType: 'timestamptz', nullable: true })
  deleted_at?: Date | null;
}

Each column follows the multi-tenant conventions: tenant_id, organization_id, timestamps, and deleted_at for soft deletes.

2. Add validators​

data/validators.ts
import { z } from 'zod';

export const upsertInventoryItemSchema = z.object({
  tenantId: z.string().uuid(),
  organizationId: z.string().uuid(),
  sku: z.string().min(1).max(64),
  name: z.string().min(1).max(128),
  quantity: z.number().int().min(0),
  location: z.string().max(128).optional(),
});

export type UpsertInventoryItemInput = z.infer<typeof upsertInventoryItemSchema>;

Use the same schema for create and update flows—call it from API handlers, CLI commands, and forms to guarantee consistent validation.

3. Generate migrations​

Register the entity in packages/inventory/tsconfig.json (or rely on path aliases already defined for the package), then run:

yarn modules:prepare
yarn db:generate

Migrations appear under packages/inventory/src/modules/inventory/migrations. Commit them alongside your entity. When you run yarn db:migrate, the new table will be created across environments.