休眠不通過生成的ID

Question

我有使用休眠映射的問題。 兩個表矩陣和matrix_value。

CREATE TABLE matrix (
    matrix_id  INT AUTO_INCREMENT, 
    number_of_rows INT NOT NULL DEFAULT 0, 
    number_of_cols INT NOT NULL DEFAULT 0, 
    PRIMARY KEY (matrix_id) 
) ENGINE =InnoDB; 

CREATE TABLE matrix_value (
    id   INT AUTO_INCREMENT, 
    matrix_id INT NOT NULL DEFAULT 0, 
    row_id  INT NOT NULL DEFAULT 0, 
    column_id INT NOT NULL DEFAULT 0, 
    matrix_val INT NOT NULL DEFAULT 0, 
    PRIMARY KEY (id), 
    CONSTRAINT FK_matrix_value_matrix 
    FOREIGN KEY (matrix_id) REFERENCES matrix (matrix_id) 
    ON UPDATE CASCADE ON DELETE CASCADE 
) ENGINE =InnoDB; 

matrix_values的生成和插入矩陣行和它 必須自動採取matrix_id並把它傳遞給matrix_values列之後，但它拋出

com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Column 'matrix_id' cannot be null 
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) 
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57) 
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) 
    at java.lang.reflect.Constructor.newInstance(Constructor.java:526) 

此外其添加到表'矩陣'附加列'matrixValues'填充null。

這裏是方法

public void fillMatrixWithValues(MatrixValue[] values) throws Exception {   
    Session session = HibernateUtils.openSession(); 
    Transaction tx = null; 
    try { 
     tx = session.getTransaction(); 
     tx.begin(); 
     if (values != null && values.length != 0) { 
      for (int i = 0; i < values.length; i++) { 
       session.saveOrUpdate(values[i]); 
      } 
      tx.commit(); 
     }  
    } catch (HibernateException e) { 
     if (tx != null) { 
      tx.rollback(); 
     } 
     logger.error("Error fillMatrixWithValues-method: " + e.getMessage()); 
     throw e; 
    }  finally { 
     session.close(); 
    } 
} 

矩陣（POJO）

@Id 
@GeneratedValue(strategy = GenerationType.IDENTITY) 
@GenericGenerator(name = "increment", strategy = "increment") 
@Column(name = "matrix_id", unique = true, nullable = false) 
private int matrixId; 

@Column(name = "number_of_rows", unique = false, nullable = false) 
private int numberOfRows; 

@Column(name = "number_of_cols", unique = false, nullable = false) 
private int numberOfCols; 

@OneToMany (mappedBy= "matrix", fetch = FetchType.EAGER) 
@Transient 
private List<MatrixValue> values; 

MatrixValues（POJO）

@Id 
@GeneratedValue(strategy = GenerationType.IDENTITY) 
@GenericGenerator(name = "increment", strategy = "increment") 
@Column(name = "id", unique = true, nullable = false) 
private int id; 

@PrimaryKeyJoinColumn 
@Column(name = "matrix_id", unique = false, nullable = false, insertable = false, updatable = false) 
private int matrixId; 

@Column(name = "row_id", unique = false, nullable = false) 
private int rowId; 

@Column(name = "column_id", unique = false, nullable = false) 
private int columnId; 

@Column(name = "matrix_val", unique = false, nullable = false) 
private int value; 

@ManyToOne 
@JoinColumn(name = "matrix_id") 
private Matrix matrix; 

getters and setters 

ħ ibernate.xml

<hibernate-configuration> 
    <session-factory> 
     <property name="connection.driver_class">com.mysql.jdbc.Driver</property> 
     <property name="connection.url">jdbc:mysql://localhost/matrixbase</property> 
     <property name="connection.username">root</property> 
     <property name="connection.password">root</property> 
     <property name="connection.pool_size">10</property> 
     <property name="dialect">org.hibernate.dialect.MySQLDialect</property> 
     <property name="show_sql">true</property> 
     <property name="hbm2ddl.auto">update</property> 
     <property name="hibernate.connection.autocommit">false</property> 
     <property name="current_session_context_class">thread</property> 
     <property name="hibernate.jdbc.batch_size">30</property> 
     <property name="hibernate.jdbc.batch_versioned_data">true</property> 
     <property name="hibernate.jdbc.use_get_generated_keys">true</property> 

     <mapping class="kuidin.task5.entity.Matrix" /> 
     <mapping class="kuidin.task5.entity.MatrixValue" /> 
<hibernate-configuration> 

什麼是錯？ 在此先感謝。

Answer 1

刪除MatrixValues類中的@Transient和matrix_id字段（帶註釋）。你也不需要。

說明：

1. 的matrixValues集合不是短暫的。它應該被持久化，儘管Matrix並不是該關聯的'擁有者'（當持久化Hibernate會查看映射字段以查找要存儲的值時，雖然這應該產生相同的值），但這稱爲'反向'側（雙向）關聯。
2. matrixValues中的matrix_id列將填充分配給矩陣字段的矩陣的id。添加額外的字段是多餘的，並註釋它爲@PrimaryKeyJoinColumn只是錯誤的：該列不是包含它的表的主鍵的一部分。