Month: September 2009

Using the Apache OpenJPA command-line tools

Stuff that’s unfortunately not concentrated into a convenient ready-to-use example in the Apache OpenJPA docs. But that’s what this blog is all about!

When using the reverse engineering, schema, and other tools directly from a shell script (not Ant or Maven), the default place to get datasource definitions and related options is in META-INF/persistence.xml. This file is mandatory even in cases where you don’t actually connect to the database, such as generating Java source from an XML schema (reverse generation).

Because the tools are using a validating parser, a schema name is REQUIRED. Example, supplying the JPA schema via the xmlns attribute:

<?xml version="1.0"?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence" version="1.0">
  <persistence-unit name="openjpa">
    <provider>org.apache.openjpa.persistence.PersistenceProviderImpl</provider>
    <properties>
      <property name="openjpa.ConnectionURL" value="jdbc:hsqldb:tutorial_database"/>
      <property name="openjpa.ConnectionDriverName" value="org.hsqldb.jdbcDriver"/>
      <property name="openjpa.ConnectionUserName" value="sa"/>
      <property name="openjpa.ConnectionPassword" value=""/>
      <property name="openjpa.Log" value="DefaultLevel=WARN, Tool=INFO"/>
      <property name="openjpa.jdbc.DBDictionary" value="StoreCharsAsNumbers=false"/>
    </properties>
  </persistence-unit>
</persistence>


CAUTION: You should delete the orm.xml file when re-running these tools. Otherwise they will use the old copy, which may not be in sync with your current efforts.

JSF Submit-on-Enter forms

It’s not (so far as I know) officially required anywhere, but it’s a generally accepted principle that a form on a web page containing one text field and one submit button should submit itself when you type in text and press the ENTER key. A classic example of this is Google .

In actuality, it isn’t quite that simple. For totally unknown reasons, Microsoft Internet Explorer requires at least two text fields and this apparently goes all the way up to and including IE8 (at least when you upgrade from IE6). Fortunately, the “spare” text field can be invisible and ignored by the application.

JSF is more complicated, and AJAX-aware JSF such as RichFaces compounds the issue even more. Here’s a solution that seems to work for me:

  <h:panelGroup>
     <h:inputText style="visibility:hidden;display:none;"
        disabled="disabled" required="false" />
     <a4j:commandButton id="ask"
        type="submit" styleClass="button1"
        action="#{forgotPassword.doAskQuestion}"
        reRender="pnl1,fpMsg" value="Submit" />
 </h:panelGroup>

I am indebted to Lincoln Baxter for this particular hidden field definition (it’s quite touchy). He’s the person behind the JSF PrettyFaces product (ocpsoft.com).

Note that this is only a kludge, and may not always work. Additionally, it causes the RichFaces a4j:commandButton oncomplete action to misbehave under both IE and Firefox (though in different ways), as of RichFaces 3.4.