我的问题是关于下面的代码:
Ingredient.java
@Entity
@Table(name = "recipes_ingredients")
public class Ingredient implements Serializable {
@Id
@Column(name = "ingredient_id")
private Long id;
@NotEmpty
private String name;
private Integer quantity;
// Getters and Setters
}
Recipe.java
@Entity
@Table(name = "recipes")
public class Recipe implements Serializable {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "recipe_id")
private Long id;
@NotEmpty
private String name;
@ManyToOne(fetch = FetchType.LAZY)
private Client client;
@OneToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL, orphanRemoval = true)
@JoinColumn(name = "fk_recipe_id")
private List<Ingredient> ingredients;
// Getters and Setters
}
我想要做的是 PK(recipes_ingredients 表)以某种方式由:ingredient_id
和 recipe_id
组成(使用我已经拥有的 FK 并使其也PK 或者只是以其他方式获取该 ID 并使用 {{1} 使其PK }).
ingredient_id
将是每个食谱从 1 开始的数字,这样如果我有一个 recipe_id = 1 和 3 成分的食谱,我的想法是在成分表中它有类似的东西这个:
ingredient_id
知道我该怎么做吗?
答案 0 :(得分:0)
public class IngredientId {
private Recipe recipe;
private Long id;
public IngredientId(Recipe recipe, Long id) {
this.recipe = recipe;
this.id = id;
}
public IngredientId() {
}
//Getters and setters are omitted for brevity
public Recipe getRecipe() {
return recipe;
}
public void setRecipe(Recipe recipe) {
this.recipe = recipe;
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
@Override
public boolean equals(Object o) {
if ( this == o ) {
return true;
}
if ( o == null || getClass() != o.getClass() ) {
return false;
}
IngredientId ingredientId = (IngredientId) o;
return Objects.equals( recipe, ingredientId.recipe ) && Objects.equals( id, ingredientId.id );
}
@Override
public int hashCode() {
return Objects.hash( recipe, id );
}
}
@Entity
@IdClass( IngredientId.class )
@Table(name = "recipes_ingredients")
public class Ingredient {
@Id
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "recipe_id")
private Recipe recipe;
@Id
@GeneratedValue
@Column(name = "ingredient_id")
private Long id;
private String name;
private Integer quantity;
public IngredientId getId() {
return new IngredientId( recipe, id );
}
public void setId(IngredientId id) {
this.recipe = id.getRecipe();
this.id = id.getId();
}
}
@Entity
@Table(name = "recipes")
public class Recipe {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "recipe_id")
private Long id;
private String name;
@OneToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL, orphanRemoval = true)
@JoinColumn(name = "recipe_id")
private List<Ingredient> ingredients = new ArrayList<>();
}
需要注意的是,复合键不能有空值。 因此,只有当您知道每种成分都与食谱相关联时,这才有意义。请参阅 this answer on StackOverflow 和 this Hibernate Jira
您可以查看 Hibernate ORM documentation 了解更多详情。