# Class Diagrams

### What are Class Diagrams?

Mermaid's class diagrams help you visualize data structures and their relationships in your projects. For analytics engineers, they're particularly useful for documenting data models, transformation logic, and system architectures.

### Creating Your First Class Diagram

1. **Launch DinoAI:** From Code IDE, access [DinoAI](https://docs.paradime.io/app-help/documentation/dino-ai) to start creating diagrams.
2. **Use a Simple Prompt:** Tell DinoAI what kind of Class Diagram you want to create. For example:

{% code overflow="wrap" %}

```
- "Create a mermaid class diagram showing my data model classes with attributes and methods"

- "Generate a mermaid class diagram for my dbt™ transformation logic with class relationships"

- "Build a mermaid class diagram showing my data pipeline components and their interactions"
```

{% endcode %}

3. **Get Your Diagram:** DinoAI will generate a complete `.mmd` file with proper Mermaid syntax.
4. **Preview Your Work:** Click the eye icon (👁️) to preview your diagram in real-time as you edit.
5. **Iterate and Refine:** Modify the generated `.mmd` file directly, or ask DinoAI to make specific changes.

#### Example:

```mermaid
---
title: Animal example
---
classDiagram
    note "From Duck till Zebra"
    Animal <|-- Duck
    note for Duck "can fly\ncan swim\ncan dive\ncan help in debugging"
    Animal <|-- Fish
    Animal <|-- Zebra
    Animal : +int age
    Animal : +String gender
    Animal: +isMammal()
    Animal: +mate()
    class Duck{
        +String beakColor
        +swim()
        +quack()
    }
    class Fish{
        -int sizeInFeet
        -canEat()
    }
    class Zebra{
        +bool is_wild
        +run()
    }
```

<figure><img src="https://2337193041-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FHET0AD04uHMgdeLAjptq%2Fuploads%2FtzRYqfBriJzgt70eyHHQ%2Fimage.png?alt=media&#x26;token=881c6179-1a83-49a9-ac49-6a4a9b3ad156" alt=""><figcaption></figcaption></figure>

{% hint style="info" %}

#### Reusable Class Diagrams prompts for you and your team

You can create custom, standardized [.dinoprompts](https://docs.paradime.io/app-help/documentation/dino-ai/dino-prompts) for Mermaid's Class Diagrams that ensure consistency across your data team. See [step-by-step guide.](https://docs.paradime.io/app-help/documentation/integrations/code-ide/mermaid-js/..#creating-mermaid-diagrams-with-.dinoprompts)
{% endhint %}

***

### Diagram Syntax Guide

#### Class Structure

A class diagram represents data objects and their relationships. Each class shows:

* The class name
* Its attributes (properties)
* Its methods (operations)

#### Basic Syntax

```mermaid
classDiagram
    class DataModel {
        +tableName: string
        +schema: string
        +refreshData()
        -validateSchema()
    }
```

#### Access Levels

Show visibility with these symbols:

* `+` : Public access
* `-` : Private access
* `#` : Protected access
* `~` : Internal access

#### Connections

Show relationships between classes:

```mermaid
classDiagram
    FactTable --> DimensionTable
    BaseModel <|-- CustomModel
```

Common relationships:

* Parent-child: `<|--`
* Contains: `*--`
* Uses: `-->`
* Optional: `o--`

### Data Team Examples

#### Data Models

```mermaid
classDiagram
    class FactSales {
        +order_date: date
        +customer_key: int
        +product_key: int
        +calculateRevenue()
    }
    class DimCustomer {
        +customer_key: int
        +customer_name: string
        +getLTV()
    }
    FactSales --> DimCustomer
```

#### Transformation Pipeline

```mermaid
classDiagram
    class Staging {
        +raw_data: table
        +clean()
        +validate()
    }
    class Warehouse {
        +processed_data: table
        +transform()
        +loadData()
    }
    Staging --> Warehouse
```

### Best Practices

1. Name classes clearly and consistently
2. Show only relevant attributes and methods
3. Group related classes together
4. Add notes for complex relationships
5. Keep diagrams focused on one aspect of your system

{% hint style="info" %}

### Additional Resources

For more syntax options and advanced features, visit the [official Mermaid documentation](https://mermaid.js.org/syntax/classDiagram.html)
{% endhint %}