1. 搭建開發環境

在開始開發餐廳後台點餐應用之前，我們需要建立一個適當的開發環境。這個環境將包括一個PostgreSQL資料庫，用於存儲應用程式的數據，以及PgAdmin，用於管理和查看資料庫內容。

使用Docker Compose搭建環境：
Docker Compose 是一個用於定義和運行多容器Docker應用程式的工具。我們將使用Docker Compose配置和運行PostgreSQL和PgAdmin容器。

1.1 創建Docker Compose文件

在執行這個步驟之前，你需要確保本地環境包含Docker。
創建一個名為docker-compose.yml的文件，我們將在其中定義我們的容器配置。

version: '3'
services:
  postgres:
    image: postgres
    container_name: restaurant-postgres
    environment:
      POSTGRES_DB: restaurant
      POSTGRES_USER: postgres
      POSTGRES_PASSWORD: postgres
    ports:
      - "5436:5432"
    volumes:
      - postgres-data:/var/lib/postgresql/data

  pgadmin:
    image: dpage/pgadmin4
    container_name: restaurant-pgadmin
    environment:
      PGADMIN_DEFAULT_EMAIL: admin@example.com
      PGADMIN_DEFAULT_PASSWORD: admin
    ports:
      - "5437:80"
    depends_on:
      - postgres

volumes:
  postgres-data:

2. SpringBoot初始化

2.1 添加相關依賴

在項目中的pom.xml添加以下主要依賴：

<dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!--  [SQL]Spring Data JPA  -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <!-- postgres SQL -->
        <dependency>
            <groupId>org.postgresql</groupId>
            <artifactId>postgresql</artifactId>
            <scope>runtime</scope>
        </dependency>
    
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            
        <!-- 其他依賴 -->
    </dependencies>

2.2 配置檔設置application.yml

spring:
  datasource:
    url: jdbc:postgresql://localhost:5436/restaurant
    driver-class-name: org.postgresql.Driver
    username: postgres
    password: postgres

  jpa:
    database-platform: org.hibernate.dialect.SQLServerDialect
    hibernate:
      ddl-auto: update

  thymeleaf:
    cache: false

3. 建立實體類

根據昨天的ERD圖

我們將進行簡化(如下圖所示)，這是因為我們只要關注Spring Boot和前面的知識點進行練習，無須將所有實體類都創建：

• 訂單表 OrderEntity

@Entity(name = "_order")
@Data
public class OrderEntity {
    @Id
    @GeneratedValue
    private Long id;

    @Column(name = "date_time")
    private LocalDateTime dateTime;

    @Column(name = "total_price")
    private Integer totalPrice;

    @Column(name = "pay_method")
    private String payMethod;

    @OneToMany(mappedBy = "order", cascade = CascadeType.ALL, orphanRemoval = true)
    private List<OrderDetailEntity> orderDetails = new ArrayList<>();  // 初始化為空列表

    public void addOrderDetail(OrderDetailEntity orderDetail) {
        orderDetails.add(orderDetail);
        orderDetail.setOrder(this);
    }

    public void removeOrderDetail(OrderDetailEntity orderDetail) {
        orderDetails.remove(orderDetail);
        orderDetail.setOrder(null);
    }
}

• 訂單明細表 OrderDetailEntity

@Entity(name = "order_detail")
@Data
public class OrderDetailEntity {

    @EmbeddedId
    private OrderDetailId id = new OrderDetailId();

    @ManyToOne
    @MapsId("orderId")
    @JoinColumn(name = "order_id")
    private OrderEntity order;

    @ManyToOne
    @JoinColumn(name = "dish_id")
    private DishEntity dish;

    private Integer count;

    private Integer total;

    @Embeddable
    @Data
    public static class OrderDetailId implements Serializable {
        @Column(name = "_order_id")
        private Long orderId;

        @Column(name = "dno")
        private Integer dno;
    }

    @Override
    public String toString() {
        return "OrderDetailEntity{";
    }
}

• 餐點表 DishEntity

@Entity(name = "dish")
@Data
public class DishEntity {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    private String name;

    private String description;

    private Integer price;

    @ManyToOne
    @JoinColumn(name = "type_id")
    private DishTypeEntity dishType;
}

• 餐點種類表 DishTypeEntity

@Entity(name = "dish_type")
@Data
public class DishTypeEntity {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    private String name;

    @OneToMany(mappedBy = "dishType")
    private List<DishEntity> dishes;
}