shield_lock
JinDaGe
← Back to skills
extension
Category: Development & EngineeringNo API key required

entity-model

Creates entity model documents with Mermaid.js ER diagrams and attribute tables defining entities, relationships, data types, and validation rules. Use when the user asks to "create an entity model", "design a data model", "draw an ERD", "define database schema", "model entities", or mentions entity-relationship diagram, ER diagram, database design, or data modeling.

personAuthor: jakexiaohubgithub
open_in_newRepositorydownloadDownload package

Entity Model

Instructions

Create or update the entity model at docs/entity_model.md based on docs/requirements.md. The document contains an ER diagram and attribute tables.

DO NOT

  • Add attributes/columns to the Mermaid diagram
  • Write prose descriptions like "Key attributes: name, email..."
  • Create a "Relationships" table
  • Skip the attribute tables

Document Structure

# Entity Model

## Entity Relationship Diagram

```mermaid
erDiagram
    ROOM_TYPE ||--o{ ROOM : "categorizes"
    GUEST ||--o{ RESERVATION : "makes"

ENTITY_NAME

One sentence describing the entity.

| Attribute | Description | Data Type | Length/Precision | Validation Rules | |-----------|-------------|-----------|------------------|-----------------------| | id | ... | Long | 19 | Primary Key, Sequence | | ... | ... | ... | ... | ... |

Required Format for Each Entity

Every entity MUST have:

  1. A ### heading with ENTITY_NAME
  2. One sentence description
  3. An attribute table with exactly 5 columns

Example Entity

ROOM_TYPE

Defines categories of rooms with shared characteristics.

| Attribute | Description | Data Type | Length/Precision | Validation Rules | |-------------|--------------------------|-----------|------------------|---------------------------| | id | Unique identifier | Long | 19 | Primary Key, Sequence | | name | Name of the room type | String | 50 | Not Null, Unique | | description | Detailed description | String | 500 | Optional | | capacity | Maximum number of guests | Integer | 10 | Not Null, Min: 1, Max: 10 | | price | Price per night in CHF | Decimal | 10,2 | Not Null, Min: 0 |

Mermaid Diagram Rules

  • Show entity names and relationships ONLY
  • NO attributes inside entity blocks
  • Use relationship syntax: ENTITY_A ||--o{ ENTITY_B : "relationship"

Validation Rules Reference

Use these values in the "Validation Rules" column (never leave empty):

| Attribute Type | Validation Rules Value | |----------------|----------------------------------| | Primary key | Primary Key, Sequence | | Required field | Not Null | | Unique field | Not Null, Unique | | Foreign key | Not Null, Foreign Key (TABLE.id) | | Optional field | Optional | | With range | Not Null, Min: X, Max: Y | | With values | Not Null, Values: A, B, C | | Email | Not Null, Format: Email |

Data Types Reference

| Data Type | Length/Precision | Usage | |-----------|------------------|-----------------------| | Long | 19 | IDs, foreign keys | | String | varies (50-500) | Text fields | | Integer | 10 | Whole numbers | | Decimal | 10,2 | Currency, percentages | | Boolean | 1 | True/false flags | | Date | - | Date only | | DateTime | - | Date and time |

Multi-Column Constraints

If validation spans multiple columns, add after the table:

Constraints: Check-out date must be after check-in date.

Workflow

  1. Read the requirements document
  2. Use TodoWrite to create a task for each entity
  3. Write the document header and ER diagram (relationships only)
  4. For each entity:
    • Write ### heading
    • Write one sentence description
    • Write attribute table with 5 columns
    • Add constraints if needed
    • Mark todo complete
  5. Validate the document:
    • Every entity in the ER diagram has a corresponding attribute table section
    • Every attribute table has exactly 5 columns
    • No attributes appear inside the Mermaid diagram entity blocks
    • All foreign keys reference existing entities
    • All validation rules use values from the Validation Rules Reference