JPA忽略實體類某屬性，不持久化某字段的解決方法

背景

JDK版本：1.8

框架：SpringBoot 2.x

ORM：JPA

目的

在表的映射實體添加一個屬性，而數據表中不必添加該字段。

 異常

執行查詢數據后，報出如下異常：

Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown column 'scheduling0_.res_name' in 'field list'
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
    at java.lang.reflect.Constructor.newInstance(Unknown Source)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
    at com.mysql.jdbc.Util.getInstance(Util.java:408)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:944)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3976)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3912)
    at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2530)
    at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2683)
    at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2486)
    at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1858)
    at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:1966)
    at com.alibaba.druid.filter.FilterChainImpl.preparedStatement_executeQuery(FilterChainImpl.java:3188)
    at com.alibaba.druid.filter.FilterEventAdapter.preparedStatement_executeQuery(FilterEventAdapter.java:465)
    at com.alibaba.druid.filter.FilterChainImpl.preparedStatement_executeQuery(FilterChainImpl.java:3185)
    at com.alibaba.druid.wall.WallFilter.preparedStatement_executeQuery(WallFilter.java:640)
    at com.alibaba.druid.filter.FilterChainImpl.preparedStatement_executeQuery(FilterChainImpl.java:3185)
    at com.alibaba.druid.filter.FilterEventAdapter.preparedStatement_executeQuery(FilterEventAdapter.java:465)
    at com.alibaba.druid.filter.FilterChainImpl.preparedStatement_executeQuery(FilterChainImpl.java:3185)
    at com.alibaba.druid.proxy.jdbc.PreparedStatementProxyImpl.executeQuery(PreparedStatementProxyImpl.java:181)
    at com.alibaba.druid.pool.DruidPooledPreparedStatement.executeQuery(DruidPooledPreparedStatement.java:228)
    at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.extract(ResultSetReturnImpl.java:60)
    ... 101 more

原因

 報出上面的異常，說明即使不加 @Column 注解，JPA也會持久化該字段。

解決

JPA不持久化某字段的解決方案

@Transient 注解表示該屬性並非一個到數據庫表的字段的映射，ORM框架將忽略該屬性。

 

這樣查詢，添加等操作就不會報錯了。查詢時，單獨邏輯對此屬性進行賦值處理，做擴展就可以了。