java.lang.IllegalState异常：在同步期间，通过未标记级联PERSIST的关系发现了一个新对象

Question

我有两个2类的关系多对多。

@Entity
@Table(name = "recipies")
public class Recipie implements Serializable {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String name;
private String url;
private String image;
@ManyToMany
@JoinTable(
        name = "recipie_ingredients",
        joinColumns = {
            @JoinColumn(name = "recipie_id", referencedColumnName = "id")},
        inverseJoinColumns = {
            @JoinColumn(name = "ingredient_id", referencedColumnName = "id")})
private List<Ingredient> ingredients = new ArrayList<>();






@Entity
@Table(name = "ingredients")
public class Ingredient implements Serializable {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;
    private String name;
    @ManyToMany(mappedBy = "ingredients") 
    private List<Recipie> recipies; 

我想用这种方式创建一个新的recipie：

List<Ingredient> ingredientsList = new ArrayList<>();


String ingredientName = "example";

Ingredient ingredient = ingredientsDao.findIngredientByName(ingredientName);

if (ingredient == null) {
   ingredient = new Ingredient();
   ingredient.setName(ingredientName);

}
ingredientsList.add(ingredient);
.....
recipie.setIngredients(ingredientsList);
recipiesDao.addRecipie(recipie);

如果数据库中不存在成分，则会出现如下错误

Caused by: java.lang.IllegalStateException: During synchronization a new object was found through a relationship that was not marked cascade PERSIST

有没有办法自动添加表中创建的对象？

我尝试添加CascateType. PERSIST但它也不工作

@ManyToMany(mappedBy = "ingredients", cascade = CascadeType.PERSIST) 
private List<Recipie> recipies; 

Answer 1

正如@Gimby所提到的，您需要分配关系的双方。

在处理@Many。。。侧面关系我总是初始化集合（您在一侧完成）：

@Entity
@Table(name = "recipies")
public class Recipie implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
    private String url;
    private String image;
    @ManyToMany
    @JoinTable(
        name = "recipie_ingredients",
        joinColumns = {
            @JoinColumn(name = "recipie_id", referencedColumnName = "id")},
        inverseJoinColumns = {
            @JoinColumn(name = "ingredient_id", referencedColumnName = "id")})
    private List<Ingredient> ingredients = new ArrayList<>();

    ...
}



@Entity
@Table(name = "ingredients")
public class Ingredient implements Serializable {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;
    private String name;
    @ManyToMany(mappedBy = "ingredients") 
    private List<Recipie> recipies = new ArrayList<>(); 

    ...
}

然后你的逻辑有一点变化：

String ingredientName = "example";

Ingredient ingredient = ingredientsDao.findIngredientByName(ingredientName);

if (ingredient == null) {
   ingredient = new Ingredient();
   ingredient.setName(ingredientName);

}
...

// Don't forget to assign both sides of the relationship
recipe.getIngredients().add(ingredient);
ingredient.getRecipies().add(recipe);
recipiesDao.addRecipe(recipe);

然后应该正确地进行级联持久化/更新。

真正的乐趣将从你试图找出如何将数量与配料联系起来开始。。。

Answer 2

首先，对于双向关系，双方都需要更新，因此：

recipe.getIngredients().add(ingredient);
ingredient.getRecipes().add(recipe);

然后，可以在传递给save（）的关系一侧将级联设置为PERSIST。因此，如果要保存配方，则应标记配方。配料

@ManyToMany(cascade = CascadeType.PERSIST)

（旁注，拼写为“recipe”，而不是“recipie”）