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POLob returns null using MySQL and jpa
 

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  1. POLob returns null using MySQL and jpa
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    <p>I'm trying to store a document as a BLOB in a java domain object that I have.</p> <p>I've seen several posts saying it can be done using @Lob for example</p> <p><a href="http://www.java2s.com/Tutorial/Java/0355__JPA/MarkByteArrayFieldAsLob.htm" rel="nofollow noreferrer">http://www.java2s.com/Tutorial/Java/0355__JPA/MarkByteArrayFieldAsLob.htm</a></p> <p>So, the problem I have is, when I store the data all seems fine, I can see it in my mysql database, however when I try to get it out within the domain object, it's always null.</p> <p>Any ideas?</p> <p>Note, the relevant getter and setter I'm using within my entity is as follows:</p> <pre><code>@Lob public byte[] getData() { return data; } public void setData(byte[] data) { this.data = data; } </code></pre> <p><strong>Update</strong> as per the comment of Pascal Thivent, I've added some code. I've also simplified the test. If I have one entity object, with two fields, an id and the data, eg</p> <pre><code>@Entity @Table(name = "picture") public class Picture extends BaseObject{ Long id; byte[] data; @Id @GeneratedValue(strategy = GenerationType.AUTO) public Long getId() { return id; } public void setId(Long id) { this.id = id; } @Lob public byte[] getData() { return data; } public void setData(byte[] data) { this.data = data; } } </code></pre> <p>Now, I have no problem creating and saving the data. However, when I try to retrieve the data just by calling a standard</p> <pre><code> this.entityManager.find(clazz, id); </code></pre> <p>Populated with the Picture.class and the relevant id, I get the following exception.</p> <p>Note one very interesting line in the exception, which i think is key is:</p> <pre><code>CausedBy: mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown column "test@email.com" </code></pre> <p>Note that "test@email.com" is the value of the byte array that I put into the data filed, so it's as if the sql is looking for a column name which is actually the name contents of the byte array. Weird!</p> <pre><code>javax.persistence.PersistenceException: org.hibernate.exception.SQLGrammarException: could not load an entity: [com.model.Picture#2] at org.hibernate.ejb.AbstractEntityManagerImpl.throwPersistenceException(AbstractEntityManagerImpl.java:630) at org.hibernate.ejb.AbstractEntityManagerImpl.find(AbstractEntityManagerImpl.java:195) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:198) at $Proxy28.find(Unknown Source) at com.service.impl.BaseManagerImpl.get(BaseManagerImpl.java:55) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:307) at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:182) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:149) at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:106) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171) at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204) at $Proxy32.get(Unknown Source) at com.service.UserManagerTest.testSaveOrUpdatePicture(UserManagerTest.java:33) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at junit.framework.TestCase.runTest(TestCase.java:154) at junit.framework.TestCase.runBare(TestCase.java:127) at junit.framework.TestResult$1.protect(TestResult.java:106) at junit.framework.TestResult.runProtected(TestResult.java:124) at junit.framework.TestResult.run(TestResult.java:109) at junit.framework.TestCase.run(TestCase.java:118) at org.eclipse.jdt.internal.junit.runner.junit3.JUnit3TestReference.run(JUnit3TestReference.java:130) at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:460) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:673) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:386) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:196) Caused by: org.hibernate.exception.SQLGrammarException: could not load an entity: [com.model.Picture#2] at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:67) at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43) at org.hibernate.loader.Loader.loadEntity(Loader.java:1874) at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:48) at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:42) at org.hibernate.persister.entity.AbstractEntityPersister.load(AbstractEntityPersister.java:3044) at org.hibernate.event.def.DefaultLoadEventListener.loadFromDatasource(DefaultLoadEventListener.java:395) at org.hibernate.event.def.DefaultLoadEventListener.doLoad(DefaultLoadEventListener.java:375) at org.hibernate.event.def.DefaultLoadEventListener.load(DefaultLoadEventListener.java:139) at org.hibernate.event.def.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:195) at org.hibernate.event.def.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:103) at org.hibernate.impl.SessionImpl.fireLoad(SessionImpl.java:878) at org.hibernate.impl.SessionImpl.get(SessionImpl.java:815) at org.hibernate.impl.SessionImpl.get(SessionImpl.java:808) at org.hibernate.ejb.AbstractEntityManagerImpl.find(AbstractEntityManagerImpl.java:175) ... 35 more Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown column 'test@email.com' in 'field list' at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27) at java.lang.reflect.Constructor.newInstance(Constructor.java:513) at com.mysql.jdbc.Util.handleNewInstance(Util.java:406) at com.mysql.jdbc.Util.getInstance(Util.java:381) at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1031) at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:957) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3376) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3308) at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1837) at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1961) at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2543) at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1737) at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:1888) at com.mysql.jdbc.BlobFromLocator.length(BlobFromLocator.java:334) at org.hibernate.type.ByteArrayBlobType.get(ByteArrayBlobType.java:89) at org.hibernate.type.AbstractLobType.nullSafeGet(AbstractLobType.java:46) at org.hibernate.type.AbstractType.hydrate(AbstractType.java:81) at org.hibernate.persister.entity.AbstractEntityPersister.hydrate(AbstractEntityPersister.java:2096) at org.hibernate.loader.Loader.loadFromResultSet(Loader.java:1380) at org.hibernate.loader.Loader.instanceNotYetLoaded(Loader.java:1308) at org.hibernate.loader.Loader.getRow(Loader.java:1206) at org.hibernate.loader.Loader.getRowFromResultSet(Loader.java:580) at org.hibernate.loader.Loader.doQuery(Loader.java:701) at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:236) at org.hibernate.loader.Loader.loadEntity(Loader.java:1860) ... 47 more </code></pre> <p>Generated SQL as per Pascal's request is:</p> <p>Hibernate: select picture0_.id as id32_0_, picture0_.data as data32_0_ from picture picture0_ where picture0_.id=?</p>
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    1. USBrian
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      1. POLob returns null using MySQL and jpa
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
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      1. USPascal Thivent
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      1. VTUpMod
    1. COWhat column type you are using on the DB side (also maybe show the annotated field of your entity)? Can you provide the generated SQL?
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      1. USPascal Thivent
    2. COit seems that mysql is generating a BLOB datatype as a result of the jpa mapping.
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      1. USBrian
    3. CONobody has any clue about this? I suspect it's a hibernate problem...
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      1. USBrian
 

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