Entities

In Mirror ORM, an Entity is a TypeScript class that accurately reflects a table in your database. Using Stage 3 Decorators to map your structure statically and ultra-fast.

The Anatomy of an Entity

A Mirror entity is made up of three pillars: the class, the unique identifier and the data columns.

import { Entity, PrimaryColumn, Column } from 'mirror-orm';

@Entity('products')
export class Product {
  @PrimaryColumn({ strategy: 'uuid_v7' })
  id!: string;

  @Column({ name: 'display_name' })
  name!: string;

  @Column({ type: 'number' })
  price!: number;
}

1. The @Entity Decorator

@Entity links your class to a table. If you do not pass a name, Mirror will use the class name as the name of the table in the database (respecting the defined case).

• Global Filters: You can define filters that apply to all queries of this entity (e.g. multi-tenancy).
• Performance: When the class is loaded, Mirror extracts the “blueprint” from the table and stores it in MetadataRegistry.

2. Column Mapping (@Column)

Mirror doesn’t try to guess types. It requires you to be explicit when data conversion is required.

• Native Type Casting: Through the type option, Mirror injects the conversion logic directly into the JIT Hydrator. This means that converting a bank string to a Date or boolean in JS happens at native V8 speed, without checking loops.
• Data Privacy: Use select: false for sensitive columns (like password_hash). They will never be brought from the bank unless you explicitly ask for them in a find({ select: [...] }).

3. Primary Key Strategies (@PrimaryColumn)

Mirror supports the most modern ID strategies on the market to avoid collisions and optimize indexing:

• identity: Lets the bank generate the ID (SERIAL, BIGSERIAL, AUTO_INCREMENT).
• uuid_v7: Generates time-sortable IDs directly in Mirror (recommended for insertion performance in large tables).
• ulid / cuid2: Native support for URL-friendly and secure identifiers.
• custom: You define the generation function.

See also: The complete column options reference is in Column Decorators. To map relations between entities, see Relationships.