Entity Relationship (@er)

Coming Soon - ER diagrams are planned for a future release.

Entity Relationship diagrams show database schemas, entities, and their relationships.

Planned Syntax

@er
[entities]
  User
    id: UUID PK
    email: VARCHAR(255) UNIQUE
    name: VARCHAR(100)
    created_at: TIMESTAMP

  Order
    id: UUID PK
    user_id: UUID FK
    status: ENUM
    total: DECIMAL
    created_at: TIMESTAMP

  OrderItem
    id: UUID PK
    order_id: UUID FK
    product_id: UUID FK
    quantity: INT
    price: DECIMAL

  Product
    id: UUID PK
    name: VARCHAR(255)
    price: DECIMAL
    stock: INT

[relationships]
  User ||--o{ Order: places
  Order ||--|{ OrderItem: contains
  Product ||--o{ OrderItem: included_in

Rendered diagram

Use Cases

• Database schema documentation

• Data model design

• API resource relationships

• Domain modeling

Planned Features

Feature	Description
Entities	Tables with attributes
Attributes	Columns with types
Primary keys	PK marker
Foreign keys	FK marker
Relationships	Cardinality notation
Constraints	UNIQUE, NOT NULL, etc.

Relationship Notation

Planned cardinality syntax:

Notation	Meaning
||--||	One to one
||--o{	One to many
o{--o{	Many to many
||--|{	One to one or many

Current Alternatives

Until @er is fully implemented, you can use @arch with cylinder shapes:

@arch
[nodes]
  users:users|cyl
  orders:orders|cyl
  items:order_items|cyl
  products:products|cyl

[edges]
  users->orders:1:N
  orders->items:1:N
  products->items:1:N

Rendered diagram

Roadmap

See the Roadmap for planned release timeline.

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