今天接續 BookStore in SurrealDB 的部分：

初始化DB及cqrs框架：

let db = Surreal::new::<Mem>(()).await?;
db.use_ns("test").use_db("test").await?;
let repo = SurrealEventRepository { db: db.clone() };

let book_service = BookService {};
let book_store: PersistedEventStore<SurrealEventRepository, Book>
    = PersistedEventStore::new_event_store(repo.clone());
let book_cqrs = CqrsFramework::new(book_store, vec![], book_service.clone());

執行書籍建檔及入庫指令：

let _ = book_cqrs.execute("test-book-1", BookCommand::CreateBook {
    id: "test-book-1".to_string(),
    title: "Rust 語言開發實戰".to_string(),
    isbn10: "1234567890".to_string(),
    description: "使用rust，併同cqrs框架，實現event sourcing".to_string(),
}).await;
let _ = book_cqrs.execute("test-book-1", BookCommand::IngestBook {
    id: "test-book-1".to_string(),
    copies: 2,
}).await;

檢查 event sourcing內容：

let events : Vec<SerializedEvent> = repo.db.query("SELECT * FROM events").await?.take(0)?;
println!("======== Events ========\n{:#?}", events);

======== Events ========
[
    SerializedEvent {
        aggregate_id: "test-book-1",
        sequence: 1,
        aggregate_type: "Book",
        event_type: "BookEvent",
        event_version: "0.1.0",
        payload: Object {
            "BookCreated": Object {
                "description": String("使用rust，併同cqrs框架，實現event sourcing"),
                "id": String("test-book-1"),
                "isbn10": String("1234567890"),
                "title": String("Rust 語言開發實戰"),
            },
        },
        metadata: Object {},
    },
    SerializedEvent {
        aggregate_id: "test-book-1",
        sequence: 2,
        aggregate_type: "Book",
        event_type: "BookEvent",
        event_version: "0.1.0",
        payload: Object {
            "BookIngested": Object {
                "copies": Number(2),
                "id": String("test-book-1"),
            },
        },
        metadata: Object {},
    },
]

序列化的event sourcing是ok的，看一下aggregate內容：

let book_store: PersistedEventStore<SurrealEventRepository, Book> = PersistedEventStore::new_event_store(repo.clone());
let book = book_store.load_aggregate("test-book-1").await.unwrap();
println!("======== Book ========\n{:#?}", book.aggregate);

======== Book ========
Book {
    id: "test-book-1",
    title: "Rust 語言開發實戰",
    isbn10: "1234567890",
    description: "使用rust，併同cqrs框架，實現event sourcing",
    copies: 2,
    lending_records: [],
    lent_history: [],
}

繼續添加一些指令試試看變化，取2個借閱指令：

let _ = book_cqrs.execute("test-book-1", BookCommand::LendBook (
    LendingRecord{
        reader_id: "test-reader-1".to_string(),
        lent_date: Utc::now(),
        due_date: Utc::now().add(chrono::Duration::days(7)),
    }
)).await;

let _ = book_cqrs.execute("test-book-1", BookCommand::LendBook (
    LendingRecord{
        reader_id: "test-reader-2".to_string(),
        lent_date: Utc::now(),
        due_date: Utc::now().add(chrono::Duration::days(7)),
    }
)).await;

event store內的aggreage看起來正確

======== Book ========
Book {
    id: "test-book-1",
    title: "Rust 語言開發實戰",
    isbn10: "1234567890",
    description: "使用rust，併同cqrs框架，實現event sourcing",
    copies: 2,
    lending_records: [
        LendingRecord {
            reader_id: "test-reader-1",
            lent_date: 2023-10-01T14:06:15.411234091Z,
            due_date: 2023-10-08T14:06:15.411237089Z,
        },
        LendingRecord {
            reader_id: "test-reader-2",
            lent_date: 2023-10-01T14:06:15.412799337Z,
            due_date: 2023-10-08T14:06:15.412800741Z,
        },
    ],
    lent_history: [],
}

event sourcing 內容

[
    SerializedEvent {
        aggregate_id: "test-book-1",
        sequence: 3,
        aggregate_type: "Book",
        event_type: "BookEvent",
        event_version: "0.1.0",
        payload: Object {
            "BookLent": Object {
                "due_date": String("2023-10-08T14:06:15.411237089Z"),
                "lent_date": String("2023-10-01T14:06:15.411234091Z"),
                "reader_id": String("test-reader-1"),
            },
        },
        metadata: Object {},
    },
    SerializedEvent {
        aggregate_id: "test-book-1",
        sequence: 3,
        aggregate_type: "Book",
        event_type: "BookEvent",
        event_version: "0.1.0",
        payload: Object {
            "BookLent": Object {
                "due_date": String("2023-10-08T14:06:15.412800741Z"),
                "lent_date": String("2023-10-01T14:06:15.412799337Z"),
                "reader_id": String("test-reader-2"),
            },
        },
        metadata: Object {},
    },
]

可以看到 sequence出現2筆都是3的部分，這部分可能是persist沒寫好，接下來要再研究一下怎麼處理這段。