dykyi-roman Mermaid Diagram Template Generator
Generate Mermaid diagrams for technical documentation.
Diagram Templates
Flowchart - Basic
flowchart TD
A[Start] --> B{Decision}
B -->|Yes| C[Action 1]
B -->|No| D[Action 2]
C --> E[End]
D --> E
Flowchart - Process
flowchart LR
subgraph Input
A[Request]
end
subgraph Processing
B[Validate]
C[Transform]
D[Store]
end
subgraph Output
E[Response]
end
A --> B --> C --> D --> E
Flowchart - Architecture Layers
flowchart TB
subgraph presentation[Presentation Layer]
direction LR
AC[Action]
RS[Responder]
end
subgraph application[Application Layer]
direction LR
UC[UseCase]
DTO[DTO]
end
subgraph domain[Domain Layer]
direction LR
EN[Entity]
VO[ValueObject]
EV[Event]
end
subgraph infrastructure[Infrastructure Layer]
direction LR
RP[Repository]
AD[Adapter]
end
presentation --> application
application --> domain
infrastructure -.-> domain
Sequence - Basic
sequenceDiagram
participant C as Client
participant S as Server
participant D as Database
C->>S: Request
S->>D: Query
D-->>S: Result
S-->>C: Response
Sequence - With Authentication
sequenceDiagram
participant C as Client
participant A as Auth
participant S as Service
participant D as Database
C->>A: Login(credentials)
A->>D: Verify user
D-->>A: User data
A-->>C: JWT Token
C->>S: Request + Token
S->>A: Validate token
A-->>S: Token valid
S->>D: Query
D-->>S: Data
S-->>C: Response
Sequence - With Error Handling
sequenceDiagram
participant C as Client
participant S as Service
participant D as Database
C->>S: Create order
alt Valid request
S->>D: INSERT order
D-->>S: order_id
S-->>C: 201 Created
else Validation error
S-->>C: 400 Bad Request
else Database error
S->>D: INSERT order
D-->>S: Error
S-->>C: 500 Internal Error
end
Sequence - Async with Queue
sequenceDiagram
participant C as Client
participant A as API
participant Q as Queue
participant W as Worker
participant D as Database
C->>A: POST /jobs
A->>D: Create job (pending)
A->>Q: Publish job
A-->>C: 202 Accepted {job_id}
W->>Q: Consume job
W->>D: Update job (processing)
W->>W: Process
W->>D: Update job (completed)
Class - Domain Model
classDiagram
class Order {
<<aggregate root>>
-OrderId id
-CustomerId customerId
-OrderStatus status
-Money total
+confirm() void
+cancel() void
+ship() void
}
class OrderItem {
<<entity>>
-OrderItemId id
-ProductId productId
-Quantity quantity
-Money price
}
class OrderStatus {
<<enumeration>>
PENDING
CONFIRMED
SHIPPED
CANCELLED
}
class Money {
<<value object>>
-int cents
-string currency
+add(Money) Money
+equals(Money) bool
}
Order "1" *-- "*" OrderItem : contains
Order --> OrderStatus : has
Order --> Money : total
OrderItem --> Money : price
Class - Repository Pattern
classDiagram
class OrderRepositoryInterface {
<<interface>>
+findById(OrderId id) Order
+save(Order order) void
+delete(OrderId id) void
}
class DoctrineOrderRepository {
-EntityManager em
+findById(OrderId id) Order
+save(Order order) void
+delete(OrderId id) void
}
class InMemoryOrderRepository {
-array orders
+findById(OrderId id) Order
+save(Order order) void
+delete(OrderId id) void
}
OrderRepositoryInterface <|.. DoctrineOrderRepository
OrderRepositoryInterface <|.. InMemoryOrderRepository
ER - Database Schema
erDiagram
users ||--o{ orders : places
orders ||--|{ order_items : contains
order_items }o--|| products : references
users {
uuid id PK
varchar email UK
varchar name
timestamp created_at
}
orders {
uuid id PK
uuid user_id FK
varchar status
int total_cents
varchar currency
timestamp created_at
}
order_items {
uuid id PK
uuid order_id FK
uuid product_id FK
int quantity
int price_cents
}
products {
uuid id PK
varchar name
varchar sku UK
int price_cents
varchar currency
}
State - Entity Lifecycle
stateDiagram-v2
[*] --> Draft : create()
Draft --> Pending : submit()
Draft --> [*] : delete()
Pending --> Approved : approve()
Pending --> Rejected : reject()
Pending --> Draft : requestChanges()
Approved --> Published : publish()
Approved --> Draft : unpublish()
Rejected --> Draft : revise()
Rejected --> [*] : delete()
Published --> Archived : archive()
Published --> Draft : unpublish()
Archived --> [*]
C4 - Context Diagram
flowchart TB
subgraph boundary[System Boundary]
S[("📦 Order Management System\n\nManages customer orders\nand inventory")]
end
C[("👤 Customer\n\nPlaces and tracks orders")]
A[("👤 Admin\n\nManages products\nand orders")]
P[("💳 Payment Gateway\n\nProcesses payments")]
E[("📧 Email Service\n\nSends notifications")]
W[("🚚 Warehouse\n\nFulfills orders")]
C -->|"Browse, Order, Track"| S
A -->|"Manage"| S
S -->|"Process payment"| P
S -->|"Send emails"| E
S -->|"Ship orders"| W
C4 - Container Diagram
flowchart TB
subgraph boundary[Order Management System]
WA[("🌐 Web App\nReact SPA")]
API[("⚙️ API\nPHP/Symfony")]
WRK[("⚡ Worker\nPHP")]
DB[("🗄️ Database\nPostgreSQL")]
CACHE[("💾 Cache\nRedis")]
Q[("📬 Queue\nRabbitMQ")]
end
C[("👤 Customer")]
P[("💳 Payment")]
E[("📧 Email")]
C -->|"HTTPS"| WA
WA -->|"REST/JSON"| API
API -->|"SQL"| DB
API -->|"Cache"| CACHE
API -->|"Publish"| Q
WRK -->|"Consume"| Q
WRK -->|"SQL"| DB
API -->|"HTTPS"| P
WRK -->|"SMTP"| E
CQRS Flow
flowchart LR
subgraph commands[Write Side]
CMD[Command] --> CH[Handler]
CH --> AG[Aggregate]
AG --> ES[Event Store]
end
subgraph events[Event Bus]
ES --> EB[Event Bus]
end
subgraph queries[Read Side]
EB --> PR[Projector]
PR --> RM[Read Model]
Q[Query] --> QH[Handler]
QH --> RM
end
Node Shapes Reference
flowchart LR
A[Rectangle] --> B(Rounded)
B --> C{Diamond}
C --> D([Stadium])
D --> E[(Database)]
E --> F((Circle))
F --> G>Asymmetric]
G --> H{{Hexagon}}
Arrow Reference
flowchart LR
A1 --> B1
A2 --- B2
A3 -.-> B3
A4 ==> B4
A5 --o B5
A6 --x B6
A7 <--> B7
A8 -->|label| B8
Styling
flowchart LR
A[Start]:::green --> B[Process]:::blue --> C[End]:::red
classDef green fill:#9f6,stroke:#333,stroke-width:2px
classDef blue fill:#69f,stroke:#333,stroke-width:2px
classDef red fill:#f66,stroke:#333,stroke-width:2px
Generation Instructions
When generating Mermaid diagrams:
- Choose appropriate type based on what you're showing
- Limit to 7±2 elements per diagram
- Use descriptive labels (not A, B, C)
- Add subgraphs for grouping
- Show direction of flow/dependencies
- Include legend if using custom styles
- Test rendering before finalizing