1

在使用 JPA 注释 OneToOne/OneToMany 从 Cassandra 检索数据时，我们得到一个空对象（参见下面的示例，其中“item”为空）。

[  
{  
  "idProduct":"095102f1-a987-4f7c-88c3-153d80b6977f",
  "item":{  
     "idItem":"b75acb06-eab6-48c1-99e9-fc7d48cf930b",
     "shortDescription":"Item 71",
     "longDescription":"An another item 71",
     "name":"Item Named 71",
     "image":"Image 71"
  },
  "options":[  
     {  
        "idProductOption":"0fa701dc-5394-47ea-86f6-e3dbf6c263da",
        "idProduct":"095102f1-a987-4f7c-88c3-153d80b6977f",
        "productOptionValue":[  
           {  
              "idProductOptionValue":"1b594b56-7767-4909-9d16-add51903c0f2",
              "idProductOption":"0fa701dc-5394-47ea-86f6-e3dbf6c263da",
              "item":null
           }
        ]
     }
  ]
}
]

如果我们直接访问“ProductOptionValue”，它会完美加载。看到它正确加载（因此，我们认为这是加载的级别限制）。

[  
{  
  "idProductOptionValue":"1b594b56-7767-4909-9d16-add51903c0f2",
  "idProductOption":"0fa701dc-5394-47ea-86f6-e3dbf6c263da",
  "item":{  
     "idItem":"17803826-0be6-4b94-813d-76abf969fa97",
     "shortDescription":"Item 41",
     "longDescription":"An item 41",
     "name":"Item Named 41",
     "image":"Image 41"
  }
}
]

我们使用以下注释来关联对象。

 @Entity
 @Table(name = "Product",  schema = "kunderaexamples@cassandra_pu")
 public class Product {
    @Id
    @Column(name = "idProduct")
    private String idProduct;

    @OneToMany(cascade = { CascadeType.ALL }, fetch = FetchType.EAGER)
    private List<ProductOption> productOption;

    @OneToOne(cascade = { CascadeType.ALL }, fetch = FetchType.EAGER)
    @JoinColumn(name = "idItem", table = "Item")
    private Item item;

    public String getIdProduct() {
        return idProduct;
    }

    public void setIdProduct(String idProduct) {
        this.idProduct = idProduct;
    }

    public List<ProductOption> getOptions() {
        return productOption;
    }

    public void setOptions(List<ProductOption> options) {
        this.productOption = options;
    }

    public Item getItem() {
        return item;
    }

    public void setItem(Item item) {
        this.item = item;
    }

    public Product() {
    }
 }

 @Entity
 @Table(name = "ProductOption",  schema = "kunderaexamples@cassandra_pu")
 public class ProductOption {
    @Id
    @Column(name = "idProductOption")
    private String idProductOption;

    @Column(name = "idProduct")
    private String idProduct;

    @OneToMany(cascade = { CascadeType.ALL }, fetch = FetchType.EAGER)
    private List<ProductOptionValue> productOptionValue;

    public String getIdProductOption() {
        return idProductOption;
    }

    public void setIdProductOption(String idProductOption) {
        this.idProductOption = idProductOption;
    }

    public List<ProductOptionValue> getProductOptionValue() {
        return productOptionValue;
    }

    public void setProductOptionValue(List<ProductOptionValue> productOptionValues) {
        this.productOptionValue = productOptionValues;
    }

    public String getIdProduct() {
        return idProduct;
    }

    public void setIdProduct(String idProduct) {
        this.idProduct = idProduct;
    }

    public ProductOption() {
    }
 }

 @Entity
 @Table(name = "ProductOptionValue",  schema = "kunderaexamples@cassandra_pu")
 public class ProductOptionValue {
    @Id
    @Column(name = "idProductOptionValue")
    private String idProductOptionValue;

    @Column(name = "idProductOption")
    private String idProductOption;

    @OneToOne(cascade = { CascadeType.ALL }, fetch = FetchType.EAGER)
    @JoinColumn(name = "idItem", table = "Item")
    private Item item;

    public String getIdProductOptionValue() {
        return idProductOptionValue;
    }

    public void setIdProductOptionValue(String idProductOptionValue) {
        this.idProductOptionValue = idProductOptionValue;
    }

    public Item getItem() {
        return item;
    }

    public void setItem(Item item) {
        this.item = item;
    }

    public String getIdProductOption() {
        return idProductOption;
    }

    public void setIdProductOption(String idProductOption) {
        this.idProductOption = idProductOption;
    }

    public ProductOptionValue() {
    }
}

@Entity
@Table(name = "Item",  schema = "kunderaexamples@cassandra_pu")
public class Item {
    @Id
    @Column(name = "idItem")
    private String idItem;

    @Column(name = "short_description")
    private String shortDescription;

    @Column(name = "long_description")
    private String longDescription;

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

    @Column(name = "image")
    private String image;

//  @Column(name = "context")
//  private Context context;
//  
//  @Column(name = "inventory")
//  private Inventory inventory;
//  
//  @Column(name = "price")
//  private ItemPrice price;

    /*
     * GETTERS AND SETTERS
     * */
    public String getIdItem() {
        return idItem;
    }

    public void setIdItem(String idItem) {
        this.idItem = idItem;
    }

    public String getShortDescription() {
        return shortDescription;
    }

    public void setShortDescription(String shortDescription) {
        this.shortDescription = shortDescription;
    }

    public String getLongDescription() {
        return longDescription;
    }

    public void setLongDescription(String longDescription) {
        this.longDescription = longDescription;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getImage() {
        return image;
    }

    public void setImage(String image) {
        this.image = image;
    }

//  public Context getContext() {
//      return context;
//  }
//
//  public void setContext(Context context) {
//      this.context = context;
//  }
//
//  public Inventory getInventory() {
//      return inventory;
//  }
//
//  public void setInventory(Inventory inventory) {
//      this.inventory = inventory;
//  }
//
//  public ItemPrice getPrice() {
//      return price;
//  }
//
//  public void setPrice(ItemPrice price) {
//      this.price = price;
//  }

    public Item() {
    }
}
4

1 回答 1

1

看起来有一些与属性名称有关的问题。

检查此链接https://github.com/impetus-opensource/Kundera/issues/158

于 2015-03-12T02:22:13.157 回答