Appliweb

Using Seam, JSF and IceFaces, I’m trying to write THE form.

I mean, even the basic stuff like a good form is not easy to do, and we’re experiencing some troubles in our project.

So I decided to try to write the « perfect » and « working in all cases » form.

What features are needed ?

1. Input must be validated. A integer field should not accept letters for example.
2. Fields can be mandatory or not
3. Erroneous fields should be highlighted, with an error message.
4. I want to select easily a date. Moreover, I want to select it, even if a mandatory field has not been set.
5. A Field can update values and rendering of other fields. Even if some fields contains errors

Well, that’s all for now. I can’t think of others features, but I’m quite sure I forgot some. We’ll add it later.

The basic:

For beginning, I’m just going to write an input field accepting integers, a date selector, and another field that is mandatory.

To do this, a few xhtml lines of code are needed:

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<ice:form id="searchForm" >
  <ice:panelGrid id="homePanelGrid" columns="2" columnClasses="rightMenu,leftMenu">
    <ice:outputLabel value="Nb Elements:" />
    <ice:inputText id="nbElements" value="#{searchPage.nbElements}" />
    <ice:outputLabel value="Not null:" />
    <ice:inputText id="notNull" value="#{searchPage.notNull}" />
    <ice:outputLabel value="Start Date:" />
    <ice:selectInputDate id="startDate" value="#{searchPage.startDate}" renderAsPopup="true" />
  </ice:panelGrid>
  <ice:commandButton id="searchAction" value="Search" action="#{searchPage.search}" />
</ice:form>

Quite easy, and the result is here:

Now, if I try to enter an invalid value in the integer field and press the button:

No error message is displayed…

We’ll see in our next chapter how to handle error messages.

As Google App. Engine uses a datanucleus plugin for database access, I’ve now switched to it (and leaved Hibernate).

Datanucleus uses bytecode instrumentation for persistance mapping, but not in real time like Hibernate does. Your classes must be enhanced just after compilation.

With maven, it’s not a problem for me, as described here:
http://www.datanucleus.org

Netbeans + Linux + Maven + datanucleus-plugin = hell

Using datanucleus-maven-plugin 1.1.4 (don’t use version 1.1.3 it will force download of Datanucleus 2.0), I get an error when running the compilation under Netbeans.

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Embedded error: Error while executing process.
java.io.IOException: error=2, No such file or directory.

I then enable the log for the plugin to see what’s happening, but get no logs. No logs at all…

Of course, nothing in the doc about this problem, so I finally searched the plugin source code:

I see that the plugin is calling « java » directly to process the enhancements. And it seems that when Netbeans calls Maven for compilation, it doesn’t provide the linux path, so the plugin couldn’t start java.

I noticed then a hidden or not-so-documented option, fork, that if set to false, will call directly the bytecode enhancer with no calls to « java ».
Here is the maven configuration to use:

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<plugin>
  <groupId>org.datanucleus</groupId>
  <artifactId>maven-datanucleus-plugin</artifactId>
  <version>1.1.4</version>
  <configuration>
    <fork>false</fork>
    <mappingIncludes>**/*.class</mappingIncludes>
    <api>JPA</api>
    <log4jConfiguration>
      ${basedir}/src/test/resources/log4j.properties
    </log4jConfiguration>
    <verbose>true</verbose>
    <enhancerName>ASM</enhancerName>
    <props>
       ${project.build.testOutputDirectory}/datanucleus.properties
    </props>
  </configuration>
  <dependencies>
    <dependency>
      <groupId>org.apache.derby</groupId>
      <artifactId>derbyclient</artifactId>
      <version>10.5.3.0_1</version>
    </dependency>
    <dependency>
      <groupId>log4j</groupId>
      <artifactId>log4j</artifactId>
      <version>1.2.12</version>
    </dependency>
  </dependencies>
</plugin>

So I tried, and this worked like a charm.
PS: The other plugin, schema-create doesn’t have this option, so I have to run it from command line.