我正在编写一个带有Basket，Product和Basket_Product表格的播放应用程序。篮子和产品有多对多关系，存储在Basket_Product中。我正在使用Ebean ORM并收到此错误
[error] Test models.ModelsTest.createAndRetrieveOrder failed: java.lang.NullPointerException: null, took 5.128 sec
[error] at models.BasketProductPk.hashCode(BasketProductPk.java:43)
[error] at java.util.HashMap.hash(HashMap.java:338)
[error] at java.util.HashMap.get(HashMap.java:556)
[error] at com.avaje.ebeaninternal.server.transaction.DefaultPersistenceContext$ClassContext.putIfAbsent(DefaultPersistenceContext.java:175)
[error] at com.avaje.ebeaninternal.server.transaction.DefaultPersistenceContext$ClassContext.access$100(DefaultPersistenceContext.java:148)
[error] at com.avaje.ebeaninternal.server.transaction.DefaultPersistenceContext.putIfAbsent(DefaultPersistenceContext.java:56)
[error] at com.avaje.ebeaninternal.server.query.SqlTreeNodeBean.load(SqlTreeNodeBean.java:235)
[error] at com.avaje.ebeaninternal.server.query.CQuery.readRow(CQuery.java:541)
[error] at com.avaje.ebeaninternal.server.query.CQuery.readBeanInternal(CQuery.java:575)
[error] at com.avaje.ebeaninternal.server.query.CQuery.hasNextBean(CQuery.java:702)
[error] at com.avaje.ebeaninternal.server.query.CQuery.readTheRows(CQuery.java:689)
[error] at com.avaje.ebeaninternal.server.query.CQuery.readCollection(CQuery.java:655)
[error] at com.avaje.ebeaninternal.server.query.CQueryEngine.findMany(CQueryEngine.java:175)
[error] at com.avaje.ebeaninternal.server.query.DefaultOrmQueryEngine.findMany(DefaultOrmQueryEngine.java:77)
[error] at com.avaje.ebeaninternal.server.core.OrmQueryRequest.findList(OrmQueryRequest.java:263)
[error] at com.avaje.ebeaninternal.server.core.DefaultServer.findList(DefaultServer.java:1502)
[error] at com.avaje.ebeaninternal.server.querydefn.DefaultOrmQuery.findList(DefaultOrmQuery.java:890)
[error] at com.avaje.ebeaninternal.util.DefaultExpressionList.findList(DefaultExpressionList.java:173)
[error] at models.ModelsTest.createAndRetrieveOrder(ModelsTest.java:100)
这是我的Junit测试，即抛出错误。当我尝试访问Basket_Product表时。我检查了我的数据库，所有内容都正确插入，我只是在尝试访问特定篮子的Basket_Product时遇到错误。
模型测试方法
@Test
public void createAndRetrieveOrder(){
Customer walter = Customer.find.where().eq("email", "test@banana_now.com").findUnique();
Product p1 = Product.find.where().idEq(1).findUnique();
Product p2 = Product.find.where().idEq(2).findUnique();
Basket b = new Basket(walter);
b.save();
new BasketProduct(p1, b, 2).save();
new BasketProduct(p2, b, 2).save();
Basket b1 = Basket.find.where().idEq(8).findUnique();
List<BasketProduct> bplist = BasketProduct.find.where().eq("basket_id", b1.id).findList();
assertNotNull(bplist);
}
嵌入式密钥
@Embeddable
public class BasketProductPk implements Serializable{
@Column(name = "product_id")
private Product product;
@Column(name = "basket_id")
private Basket basket;
public BasketProductPk(Product product, Basket basket) {
this.product = product;
this.basket = basket;
}
@Override
public boolean equals(Object otherOb) {
if (this == otherOb) {
return true;
}
if (!(otherOb instanceof BasketProductPk)) {
return false;
}
BasketProductPk other = (BasketProductPk) otherOb;
return (
(product==null?other.product==null:product.equals
(other.product)
)
&&
(basket == other.basket)
);
}
@Override
public int hashCode() {
return (
(product==null?0:product.hashCode())
^
(basket.hashCode())
);
}
}
篮子产品
@Entity
@Table(name = "basket_product")
public class BasketProduct extends Model {
@EmbeddedId
public BasketProductPk id;
@ManyToOne(cascade= CascadeType.ALL)
@JoinColumn(name="product_id")
public Product product;
@ManyToOne(cascade=CascadeType.ALL)
@JoinColumn(name="basket_id")
public Basket basket;
public int quantity;
public float subtotal;
public BasketProduct(Product product, Basket basket, int quantity){
this.id = new BasketProductPk(product, basket);
this.product = product;
this.basket = basket;
this.quantity = quantity;
this.subtotal = quantity * product.price;
}
protected BasketProduct() {}
public static Finder<String, BasketProduct> find = new Finder<String, BasketProduct>(String.class, BasketProduct.class);
// getters, setters
}
产品
@Entity
public class Product extends Model{
@Id
public int id;
public String name;
public Float price;
public String category;
public String subcategory;
public String image_url;
public String url;
@ManyToOne
private Store store;
@OneToMany(cascade = CascadeType.ALL, mappedBy = "product")
private List<BasketProduct> basket_product;
public Product(String name, Float price, String category, String subcategory, String image_url, String url, Store store){
this.name = name;
this.price = price;
this.category = category;
this.subcategory = subcategory;
this.image_url = image_url;
this.url = url;
this.store = store;
}
public static Finder<String, Product> find = new Finder<String, Product>(String.class, Product.class);
}
篮
@Entity
public class Basket extends Model {
@Id
public int id;
@CreatedTimestamp
public Timestamp time;
int complete;
@ManyToOne
public Customer customer;
@ManyToOne
public Employee employee;
@OneToMany(cascade = CascadeType.ALL, mappedBy = "basket")
public List<BasketProduct> basket_product;
public Basket(Customer customer){
this.customer = customer;
this.complete = 0;
}
public Basket(Customer customer, Employee employee){
this.customer = customer;
this.employee = employee;
}
public static Finder<String, Basket> find = new Finder<String, Basket>(String.class, Basket.class);
}