java.lang.IllegalStateException: org.hibernate.TransientPropertyValueException

java.lang.IllegalStateException: org.hibernate.TransientPropertyValueException

提问by Laurence Geng

My application has two entity Product and Category. When add product , user choose the category that product belong to. But when save the product to data base i meet the error

我的应用程序有两个实体产品和类别。添加产品时，用户选择产品所属的类别。但是当将产品保存到数据库时，我遇到了错误

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.IllegalStateException: org.hibernate.TransientPropertyValueException: Not-null property references a transient value - transient instance must be saved before current operation

org.springframework.web.util.NestedServletException：请求处理失败；嵌套异常是 java.lang.IllegalStateException: org.hibernate.TransientPropertyValueException: Not-null 属性引用了一个瞬态值 - 在当前操作之前必须保存瞬态实例

the content of entity is Category.java

实体的内容是 Category.java

@Entity
@Table(name="category")
public class Category {

@Id
@GeneratedValue(strategy=GenerationType.AUTO)
private long id;

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

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

@OneToMany(mappedBy = "category", fetch=FetchType.LAZY)
private Set<Product> products;

//getter and setter method
}

Product.java

产品.java

@Entity
@Table(name="product")
public class Product {

@Id
@GeneratedValue(strategy=GenerationType.AUTO)
private long id;

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

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

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

@Column(name="price")
private long price;

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

@ManyToOne
@JoinColumn(name = "category_id", referencedColumnName = "id", nullable = false)
Category category;

//getter and setter method
}

ProductDAO.java

产品DAO.java

@Repository("ProductDAO")
@Transactional
public class ProductDAO {

@PersistenceContext
private EntityManager entityManager;

public EntityManager getEntityManager() {
    return entityManager;
}

public void setEntityManager(EntityManager entityManager) {
    this.entityManager = entityManager;
}

public void create(Product product) {
    entityManager.merge(product.getCategory());
    entityManager.persist(product);
}
//other method
}

my jsp file

我的jsp文件

<form:form method="post" commandName="product" action="add.html" enctype="multipart/form-data">
    Productname <form:input path="name"/>
                <form:errors path="name" class ="error"/><br>
    description    <form:input   path="description"/><br>
    price    <form:input   path="price"/><br>
    manufacture <form:input path="manufacture"/><br>
    Category
    <form:select path="category">
    <form:options items="${categories}" itemValue="id" itemLabel="categoryName" />
    </form:select>
    <form:errors path="category" class ="error"/><br>
    <br/>
    Product image<input type="file" name="file" />
    <form:errors path="imageName" class ="error"/><br>
    <input type="submit" class="register" value="Save">
</form:form>

my Converter

我的转换器

public class CategoryConverter implements Converter<String, Category>{

    @Autowired
    private CategoryService categoryService;

    public Category convert(String id) {
        return categoryService.findById(Long.valueOf(id));
    }
}

thank for any help

感谢您的帮助

回答by Laurence Geng

please add (cascade=CascadeType.ALL) into category field mapping of Product

请将 (cascade=CascadeType.ALL) 添加到 Product 的类别字段映射中

@ManyToOne(cascade=CascadeType.ALL)
@JoinColumn(name = "category_id", referencedColumnName = "id", nullable = false)
Category category;

and remove this line in ProductDAO:

并在 ProductDAO 中删除此行：

entityManager.merge(product.getCategory());

NOTE: if your product's category is an existing one, you should load it first then set it to your product, this is normal flow. Do not new duplicated Category object.

注意：如果您的产品类别是现有的，您应该先加载它，然后将其设置为您的产品，这是正常流程。不要新建重复的 Category 对象。

回答by Laurence Geng

This my fixed code

这是我的固定代码

@Transactional
public void create(Product product) {
    Category category=categoryDAO.findById(product.getCategory().getId());
    category.getProducts().add(product);
    categoryDAO.edit(category);
    product.setCategory(category);
    this.productDAO.create(product);
}