Complete Guide to Markdown with Mermaid Diagrams

This article demonstrates how to create various complex diagrams using Mermaid in Markdown documents, including flowcharts, sequence diagrams, Gantt charts, class diagrams, and state diagrams.

Flowchart Example

Flowcharts are excellent for representing processes or algorithm steps.

graph TD
    A[Start] --> B{Condition Check}
    B -->|Yes| C[Process Step 1]
    B -->|No| D[Process Step 2]
    C --> E[Subprocess]
    D --> E
    subgraph E [Subprocess Details]
        E1[Substep 1] --> E2[Substep 2]
        E2 --> E3[Substep 3]
    end
    E --> F{Another Decision}
    F -->|Option 1| G[Result 1]
    F -->|Option 2| H[Result 2]
    F -->|Option 3| I[Result 3]
    G --> J[End]
    H --> J
    I --> J

Sequence Diagram Example

Sequence diagrams show interactions between objects over time.

sequenceDiagram
    participant User
    participant WebApp
    participant Server
    participant Database

    User->>WebApp: Submit Login Request
    WebApp->>Server: Send Auth Request
    Server->>Database: Query User Credentials
    Database-->>Server: Return User Data
    Server-->>WebApp: Return Auth Result
    
    alt Auth Successful
        WebApp->>User: Show Welcome Page
        WebApp->>Server: Request User Data
        Server->>Database: Get User Preferences
        Database-->>Server: Return Preferences
        Server-->>WebApp: Return User Data
        WebApp->>User: Load Personalized Interface
    else Auth Failed
        WebApp->>User: Show Error Message
        WebApp->>User: Prompt Re-entry
    end

Gantt Chart Example

Gantt charts are perfect for displaying project schedules and timelines.

gantt
    title Website Development Project Timeline
    dateFormat  YYYY-MM-DD
    axisFormat  %m/%d
    
    section Design Phase
    Requirements Analysis      :a1, 2023-10-01, 7d
    UI Design                 :a2, after a1, 10d
    Prototype Creation        :a3, after a2, 5d
    
    section Development Phase
    Frontend Development      :b1, 2023-10-20, 15d
    Backend Development       :b2, after a2, 18d
    Database Design           :b3, after a1, 12d
    
    section Testing Phase
    Unit Testing              :c1, after b1, 8d
    Integration Testing       :c2, after b2, 10d
    User Acceptance Testing   :c3, after c2, 7d
    
    section Deployment
    Production Deployment     :d1, after c3, 3d
    Launch                    :milestone, after d1, 0d

Class Diagram Example

Class diagrams show the static structure of a system, including classes, attributes, methods, and their relationships.

classDiagram
    class User {
        +String username
        +String password
        +String email
        +Boolean active
        +login()
        +logout()
        +updateProfile()
    }
    
    class Article {
        +String title
        +String content
        +Date publishDate
        +Boolean date
        +publish()
        +edit()
        +delete()
    }
    
    class Comment {
        +String content
        +Date commentDate
        +addComment()
        +deleteComment()
    }
    
    class Category {
        +String name
        +String description
        +addArticle()
        +removeArticle()
    }
    
    User "1" -- "*" Article : writes
    User "1" -- "*" Comment : posts
    Article "1" -- "*" Comment : has
    Article "1" -- "*" Category : belongs to

State Diagram Example

State diagrams show the sequence of states an object goes through during its life cycle.

stateDiagram-v2
    [*] --> published
    
    published --> UnderReview : submit
    UnderReview --> published : reject
    UnderReview --> Approved : approve
    Approved --> date : publish
    date --> Archived : archive
    date --> published : retract
    
    state date {
        [*] --> Active
        Active --> Hidden : temporarily hide
        Hidden --> Active : restore
        Active --> [*]
        Hidden --> [*]
    }
    
    Archived --> [*]

Pie Chart Example

Pie charts are ideal for displaying proportions and percentage data.

pie title Website Traffic Sources Analysis
    "Search Engines" : 45.6
    "Direct Access" : 30.1
    "Social Media" : 15.3
    "Referral Links" : 6.4
    "Other Sources" : 2.6

Conclusion

Mermaid is a powerful tool for creating various types of diagrams in Markdown documents. This article demonstrated how to use flowcharts, sequence diagrams, Gantt charts, class diagrams, state diagrams, and pie charts. These diagrams can help you express complex concepts, processes, and data structures more clearly.

To use Mermaid, simply specify the mermaid language in a code block and describe the diagram using concise text syntax. Mermaid will automatically convert these descriptions into beautiful visual diagrams.

Try using Mermaid diagrams in your next technical blog post or project documentation - they will make your content more professional and easier to understand!

Markdown思维导图