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DOM4J Mode Problem preserving whitespace in strings

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akiel

Post subject: DOM4J Mode Problem preserving whitespace in strings

Posted: Thu Jul 12, 2007 6:02 am

Newbie

Joined: Mon Sep 04, 2006 9:03 am
Posts: 9

Hibernate version:
3.2.4.sp1

Mapping documents:

Code:

<hibernate-mapping>
    <class name="de.uni_leipzig.lots.common.objects.News" table="news" node="news">          
        <id name="id" column="id" type="long" unsaved-value="null" node="@id">    
            <generator class="increment"/>
        </id>            
        <property name="headline" length="255" not-null="true"/>            
        <property name="message" type="text" not-null="true"/>        
    </class>    
</hibernate-mapping>

Code between sessionFactory.openSession() and session.close():

Code:

Session dom4jSession = session.getSession(EntityMode.DOM4J);
Element xmlNews = dom4jSession.get(News.class, id);
StringWriter writer = new StringWriter();
XMLWriter xmlWriter = new XMLWriter(writer, DOM4JHelper.getPrettyPrintOutputFormat());
xmlWriter.write(xmlNews);
xmlWriter.close();

Full stack trace of any exception that occurs:
--

Name and version of the database you are using:
--

The generated SQL (show_sql=true):
--

Debug level Hibernate log excerpt:
--

My problem is, that whitespaces in the message string of the news are not preserved in the XML output. I use DOM4J as backup/restore of all my entities. The last unsolved problem is that whitespaces are not preserved.
With whitespaces I mean line breaks and normal spaces. For some strings of my entities it is important to preserve those.

What do I get as XML?

Code:

<news id="1">
    <headline>Testnews</headline>
    <message>First line Second line Third line</message>
</news>

What do I want?

Code:

<news id="1">
    <headline>Testnews</headline>
    <message><![CDATA[First line
Second line
Third line]]></message>
</news>

Code:

<news id="1">
    <headline>Testnews</headline>
    <message xml:space="preserve">First line
Second line
Third line</message>
</news>

Hibernate produces a org.dom4j.tree.DefaultText node for the message text which includes the string "First line\nSecond line\nThird line" which is right. But the XMLWriter from dom4j trims this line breaks, because the text node is no CDATA and the sourrounding <message> node does not have the xml:space="preserve" attribute.

So hibernate should add the xml:space="preserve" attribute to the <message> node or generate a CDATA text node if I want preserve whitespaces for a particular property. So we need a possibility to declare a property to be space preserving in DOM4J mode.

What do you think about this? Should a file a feature request?

Thanks

Alexander Kiel
Univeristy of Leipzig, Germany

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akiel

Post subject:

Posted: Thu Jul 12, 2007 7:09 am

Newbie

Joined: Mon Sep 04, 2006 9:03 am
Posts: 9

I did a step-by-step debug run through the Hibernate code. I think org.hibernate.type.Type#setToXMLNode(Node, Object, SessionFactoryImplementor) should do the magic.

In my case I use the type "text" for my message property. The TextType uses the setToXMLNode implementation from NullableType which reads:

Code:

public void setToXMLNode(Node xml, Object value, SessionFactoryImplementor factory) 
throws HibernateException {
    xml.setText( toXMLString(value, factory) );
}

I can think about a type which adds first a CDATA node to the xml node and than the string as text to the CDATA node or the type can add a "xml:space="preserve" attribute to the xml node.

Even the implementation of the ClobType does not do anything to preserve whitespaces:

Code:

public void setToXMLNode(Node node, Object value, SessionFactoryImplementor factory) {
   if (value!=null) {
      Clob clob = (Clob) value;
      try {
         int len = (int) clob.length();
         node.setText( clob.getSubString(0, len) );
      }
      catch (SQLException sqle) {
         throw new HibernateException("could not read XML from Clob", sqle);
      }
   }
}

And (a little bit off topic) the BinaryType did not use Base64 to output to XML. Instead it uses Hex Strings. Base64 should be preferred. And even worse the BlobType throws a UnsupportedOperationException("todo").

So I will try to implement a Type which preserves spaces in XML. It will be a little bit difficult, because it seems I can't do it with a UserType.

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