java.lang.IllegalStateException: org.hibernate.Tra

问题:

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

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

the content of entity is 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

@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

@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

<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

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

回答1:

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

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

and remove this line in ProductDAO:

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.

回答2:

This my fixed code

@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);
}