v2-marketplace/data-modeler
Creates entity model documents with Mermeaid.js ER diagrams and attribute tables.
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- name:
- data-modeler
- description:
- Creates entity model documents with Mermaid.js ER diagrams and attribute tables. Use when asked to design a database schema, create an ERD, build an entity relationship diagram, model data entities, visualize a database design, or produce a data model document with structured attribute definitions.
Data Modeler
Instructions
Create an entity model document with 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:
- A ### heading with ENTITY_NAME
- One sentence description
- 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 |
| 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
- Read the requirements document
- Use TodoWrite to create a task for each entity
- Write the document header and ER diagram (relationships only)
- For each entity:
- Write ### heading
- Write one sentence description
- Write attribute table with 5 columns
- Add constraints if needed
- Mark todo complete
- Verify every entity has an attribute table
- Workspace
- v2-marketplace
- Visibility
- Public
- Created
- Last updated
- Publish Source
- GitHub
- Badge
