Datamodellm

---
name: datamodellm
description: Create visual data models for database schemas using Nimbalyst's DataModelLM editor. Use when the user wants to design a data model, database schema, entity relationship diagram, or Prisma schema.
---

# DataModelLM - Visual Data Modeling

DataModelLM is Nimbalyst's visual editor for creating database schemas using Prisma format. It displays entity-relationship diagrams with a visual canvas.

## When to Use DataModelLM

- Designing database schemas
- Creating entity relationship diagrams (ERDs)
- Planning data models for applications
- Working with Prisma schemas
- Any visual data modeling task

## File Format

- **Extension**: `.prisma`
- **Format**: Prisma schema with special metadata header
- **Location**: Any directory (commonly workspace root or `models/`, `schema/`)

### Required Header

Every DataModelLM file MUST start with a `@nimbalyst` metadata comment:

```prisma
// @nimbalyst {"viewport":{"x":0,"y":0,"zoom":1},"positions":{},"entityViewMode":"standard"}
```

### Basic Structure

```prisma
// @nimbalyst {"viewport":{"x":0,"y":0,"zoom":1},"positions":{},"entityViewMode":"standard"}

datasource db {
  provider = "postgresql"
  url      = env("DATABASE_URL")
}

model User {
  id        Int      @id @default(autoincrement())
  email     String   @unique
  name      String?
  posts     Post[]
  createdAt DateTime @default(now())
  updatedAt DateTime @updatedAt
}

model Post {
  id        Int      @id @default(autoincrement())
  title     String
  content   String?
  published Boolean  @default(false)
  author    User     @relation(fields: [authorId], references: [id])
  authorId  Int
  createdAt DateTime @default(now())
}
```

## Supported Types

### Scalar Types
- `Int`, `BigInt`, `Float`, `Decimal`
- `String`, `Boolean`
- `DateTime`, `Json`, `Bytes`

### Modifiers
- `?` - Optional field
- `[]` - Array/list

### Attributes
- `@id` - Primary key
- `@unique` - Unique constraint
- `@default(value)` - Default value
- `@updatedAt` - Auto-update timestamp
- `@relation` - Define relationships

## Relationship Patterns

### One-to-Many
```prisma
model User {
  posts Post[]
}
model Post {
  author   User @relation(fields: [authorId], references: [id])
  authorId Int
}
```

### One-to-One
```prisma
model User {
  profile Profile?
}
model Profile {
  user   User @relation(fields: [userId], references: [id])
  userId Int  @unique
}
```

### Many-to-Many (Implicit)
```prisma
model Post {
  categories Category[]
}
model Category {
  posts Post[]
}
```

## Best Practices

1. **Always include the @nimbalyst header** - Required for visual editor
2. **Use meaningful model names** - PascalCase, singular (User not Users)
3. **Include timestamps** - Add createdAt and updatedAt to most models
4. **Define explicit relations** - Always specify @relation with fields and references