Blobs may not be accessed after serialization

wouterv · **Joined:** Sun Feb 29, 2004 4:18 pm **Posts:** 7

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Hibernate version:3.1 beta 5

Full stack trace of any exception that occurs:
Blobs may not be accessed after serialization
Stack Trace:

* org.hibernate.lob.SerializableBlob.getWrappedBlob(SerializableBlob.java:23)
* org.hibernate.lob.SerializableBlob.getBinaryStream(SerializableBlob.java:39)
* nl.huib.swiet.dao.impl.hibernate.ItemDAOImpl.saveOrUpdateItem(ItemDAOImpl.java:155)
* nl.huib.swiet.service.shop.ItemService.saveOrUpdateItem(ItemService.java:49)
* nl.huib.swiet.service.shop.ItemService$$FastClassByCGLIB$$b5303db5.invoke(<generated>)
* net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:149)
* org.springframework.aop.framework.Cglib2AopProxy$CglibMethodInvocation.invokeJoinpoint(Cglib2AopProxy.java:661)
* org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:122)
* org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:57)
* org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:144)
* org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:606)
* <censored>.ItemService$$EnhancerByCGLIB$$5dd13c60.saveOrUpdateItem(<generated>)

Name and version of the database you are using: MySQL 4.1

The generated SQL (show_sql=true):
Hibernate: update item set sold=?, width=?, height=?, thumbnail_medium=?, stock=?, name_nl=?, description_en=?, description_nl=?, name_en=?, buy_price=?, buy_date=?, in_shop=?, new_item=?, archived=?, sale_price=?, depth=? where id=?

Hi,

I have a problem updating a class which has a blob in it. During the operation I only loaded it via another object, so the blob probably isn't initialized (lazy is default). Then I set just a simple property on the object and call saveOrUpdate, which generates the above exception. I check the code and it seems the internal blob is null.
Could this be a bug, am I doing something wrong? I'm using annotations and I do not add anything to the blob getter, so I'm using defaults.

Regards,
Wouter

gavin · **Posted:** Fri Oct 07, 2005 7:41 am

This is pretty much just a limitation of JDBC blobs. They may not be accessed outside the txn they were retrieved in.

wouterv · **Joined:** Sun Feb 29, 2004 4:18 pm **Posts:** 7

So what are my options? I tried to Hibernate.initialize the object within the new transaction, but that didn't work. session.lock on it -no luck there-

Any hints/suggestions?
Wouter

koda2 · **Joined:** Wed Sep 28, 2005 5:30 pm **Posts:** 25

gavin wrote:

This is pretty much just a limitation of JDBC blobs. They may not be accessed outside the txn they were retrieved in.

Gavin, this seems to contradict what is written here: http://www.hibernate.org/250.html#A15

It explicitly states that classes containing SerializableBlobs can now be "detached, serialized, deserialized, and passed to merge()". So which is it? Does Session.merge() attach a new SerializableBlob to the enclosing object?

koda2 · **Joined:** Wed Sep 28, 2005 5:30 pm **Posts:** 25

FYI: I just ran a local test and it seems to confirm what I suspected, Session.merge() creates a new SerializableBlob so you can use Blob properties across sessions or serialization.

If I don't use Session.merge() I get the same exception as wouterv reported. Gavin, can you please mention this in the documentation?

devmaster · **Joined:** Thu Jan 04, 2007 3:48 pm **Posts:** 5

hello again.

I felt compelled to re open this discussion as the last post was in 2005 and this is now 2008.

Using the serializableblob as described here:
http://www.hibernate.org/250.html#A15 and in this post, I am still getting the error,

Code:

java.lang.IllegalStateException: Blobs may not be accessed after serialization

I am using EJB3, Jboss 4.2, w/Oracle10g

Here is what is in my entity:

Code:

    @Lob 
    @Basic(fetch=FetchType.LAZY)
    @Column(name="ART_FILE", nullable=false)
    public SerializableBlob getFile()
    {
        return file;
    }
    public void setFile(SerializableBlob file)
    {
        this.file = file;
    }

Here is my a snippet in the EJB that fails:

Code:

                SerializableBlob blob = (SerializableBlob)artFile.getFile();
                
                try
                {
                    if( (blob == null) || (blob.getBytes(0, new Integer(blob.length() + "")).length == 0 ) )
                    {
                        throw new InvalidArtFileException("The file size of the art file must be greater than 0 bytes!  ArtFile number " + i);
                    }
                }
                catch (SQLException e)
                {
                    logger.error("Caught SQL Exception while trying to determine the size of a file.",e);
                }

The above code that checks the length of the blob is running in a loop, thats the reason for the +i on the exception.

I am running a junit test case which is where the err occurs. My thoughts are that since this is a serializable blob that it shouldnt matter that I am running from junit to the ejb.

Here is the code used to put the blob into the entity (from the test case)

Code:

       File file=new File("C:\\Documents and Settings\\couldbeyou\\Desktop\\chicago\\IMAGE_129.jpg");
        FileInputStream fInSteam = new FileInputStream(file);
        BufferedInputStream bInputStream = new BufferedInputStream(fInSteam);
        ByteArrayOutputStream bOutputStream = new ByteArrayOutputStream();        
        int nextByte;
        
        while (( nextByte = bInputStream.read() ) != - 1)
        {
        bOutputStream.write(nextByte);
        }
        // Bob the builder builds a blob.        
        blob = (SerializableBlob)org.hibernate.Hibernate.createBlob(bOutputStream.toByteArray());
        }

this part seems to work fine, and if I remove the code from the EJB that checks the blob length and not null then I can see in the DB that it was persisted and a blob is present.

Any thoughts? Why am I getting this err using serializableblob? what can I do to not get this err using serializableblob?