Internationalized Labels for Form Components in Wicket - internationalization

Question

How do I correctly create internationalized labels for my form components so that when displaying feedback messages an internationalized field name is displayed instead of the name of the field in the java code?
I've read this:
https://cwiki.apache.org/WICKET/everything-about-wicket-internationalization.html
as well as the documentation for wicket's xhtml tags:
https://cwiki.apache.org/WICKET/wickets-xhtml-tags.html
<label wicket:for="name">
<wicket:label>
<wicket:message key="label.name"/>
</wicket:label>
</label>
<input wicket:id="name" type="text" wicket:message="placeholder:label.name" />
This results in the following error:
Last cause: Expected close tag for '<wicket:label>' Possible attempt to embed
component(s) '<wicket:message key="label.name"/>' in the body of this
component which discards its body
If I replace the wicket:message with some arbitrary text it displays the text in any associated feedback messages.
(There's a related jira issue: https://issues.apache.org/jira/browse/WICKET-3903 however I still do not understand what has been done to fix this and what I must do ...)
Just found out there is a way to do this in java:
add(new TextField<String>("name").setRequired(true).setLabel(new Model<String>(getString("label.name"))));
Is it possible to somehow do this in a more comfortable way?

Answer 1

I just tested the following:
<form wicket:id="form">
<label for="input"><wicket:message key="input">some input</wicket:message></label>
<input wicket:id="input" type="text" name="input">
<input type="submit" value="submit">
</form>
And in the java class:
Form<HomePage> form = new Form<HomePage>("form"
, new CompoundPropertyModel<HomePage>(this));
wmc.add(form);
TextField textField = new TextField("input");
textField.setRequired(true);
form.add(textField);
In the property file I provided:
input=SomeInputField
This led to the following screen (if I leave the requiered field empty and press submit.
Is this what you are looking for?

Answer 2

Here is an alternative approach to #bert's that has always worked for me (wasn't aware of <wicket:label>)
The text shown for a FormComponent when a validation error occurs can be specified by means of FormComponent.setLabel(IModel). The shown text will be the result of the IModel's getObject().
TextField comp = new TextField("comp");
// Use internationalized text from XML resource file
comp.setLabel(new StringResourceModel("formResources.comp.label", this, null));
Notice this has nothing to do with <label> nor FormComponentLabel. FormComponentLabel is a component that can be used to model <label> tags.
You could even subclass FormComponentLabel to provide the label text based on FormComponent.getLabel(), and maybe output an extra mark when the field is required:
public class MyLabel extends SimpleFormComponentLabel{
private boolean required;
public MyLabel (String id, LabeledWebMarkupContainer labelProvider) {
super(id, labelProvider);
if (labelProvider instanceof FormComponent){
required = ((FormComponent)labelProvider).isRequired();
}
}
protected void onComponentTagBody(final MarkupStream markupStream,
final ComponentTag openTag) {
String mark = "";
if (required){
// could be for instance "*"
mark = getString("formResources.requiredField");
}
String text = getModelObjectAsString() + mark;
replaceComponentTagBody(markupStream, openTag, text);
}
}
{
TextField component = new TextField("component");
component.setRequired(true);
component.setOutputMarkupId(true);
IModel labelModel = new StringResourceModel("formResources.component.label",
this, null);
component.setLabel(labelModel);
add(component);
add(new MyLabel("componentLabel", component);
}
<label wicket:id="componentLabel"/>
<input type="text" wicket:id="component"/>
This way you would have clean way of
Setting the FormComponent's text to an internationalized resource string
Reusing exactly the same resource string transparently for the <label> tag and even adding custom marks to it based on FormComponent's properties.

Answer 3

Another alternative is to use the key attribute of <wicket:label/>, like so:
<label wicket:for="name">
<wicket:label key="label.name">Placeholder label</wicket:label>
</label>
<input wicket:id="name" type="text"/>
Unfortunately this attribute is not documented on the wiki page describing wicket's xhtml tags. All attributes supported are documented using JavaDoc in the class handling the tag (org.apache.wicket.markup.html.form.AutoLabelTextResolver).
The advantage of this alternative is that there is no additional coding required.

Answer 4

Wicket throws an exception to tell you that your <wicket:message> tag will be removed because the body of the <wicket:label> tag is replaced. The problem is you cannot nest the <wicket:message> tag inside the <wicket:label> tag (and shouldn't need to).
either this (Option 1):
<label wicket:for="name">
<wicket:label key="label.name"/>
</label>
<input wicket:id="name" type="text />
or this (Option 2):
<label wicket:for="name">
<wicket:message key="label.name"/>
</label>
<input wicket:id="name" type="text />
should work for you and result in HTML something like the following (assuming the properties file contains label.name=Name):
<label for="someMarkupId">
Name
</label>
<input id="someMarkupId" type="text" />
The difference is that if you set the label for the component through the Java code like so:
component.setLabel(new Model("value set in code"));
then using the Option 1 will result in the label being set to "value set in code", while using Option 2 will still result in the label set to "Name". Also if the label is set through Java code, and the key is missing from the properties file the Option 2 will throw an exception, while Option 1 will simply use the value set in the code.

Answer 5

I prefer this:
<label wicket:for="name"><wicket:label />:</label>
<input type="text" wicket:id="name"></input>
Just make sure to set the label in the FormComponent using setLabel, so the only java needed is:
add(new TextField("name", nameModel).setLabel(Model.of("i18n.name")));
This will be rendered as (in Dutch):
<label id="name63-w-lbl" for="name63">Naam:</label>
<input type="text" value="" name="name" id="name63">