### Clone Wicket Tutorial Examples Repository

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/howToSource.adoc

Use this command to get a local copy of the Wicket tutorial examples from GitHub.

```bash
git clone https://github.com/bitstorm/Wicket-tutorial-examples.git
```

--------------------------------

### Install Graphite on Mac using Homebrew

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/monitoring/monitoring_2.adoc

These commands provide a quick setup guide for installing Graphite and its dependencies on a macOS system using Homebrew and pip. Remember to adjust ownership and configuration files as indicated.

```bash
brew install python
```

```bash
brew install cairo
```

```bash
brew install py2cairo
```

```bash
pip install Django==1.5
```

```bash
pip install "django-tagging<0.4"
```

```bash
sudo pip install carbon
```

```bash
pip install whisper
```

```bash
sudo pip install graphite-web
```

```bash
sudo pip install Twisted==11.1.0
```

```bash
sudo chown -R <your username>:staff /opt/graphite
```

```bash
cp /opt/graphite/conf/carbon.conf{.example,}
```

```bash
cp /opt/graphite/conf/storage-schemas.conf{.example,}
```

```bash
cd /opt/graphite/webapp/graphite
```

```bash
cp local_settings.py{.example,}
```

```bash
python manage.py syncdb
```

```bash
python /opt/graphite/bin/carbon-cache.py start
```

```bash
python /opt/graphite/bin/run-graphite-devel-server.py /opt/graphite
```

--------------------------------

### Preview Wicket Guide Changes

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/contributing.adoc

Build and preview the Wicket user guide changes by running this Maven command in the 'wicket/wicket-user-guide' directory. This command compiles the guide and generates HTML/PDF output.

```bash
mvn clean package -P guide
```

--------------------------------

### XML Resource Bundle Example

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/i18n/i18n_2.adoc

An example of an XML file used as a resource bundle, containing a greeting message in simplified Chinese. Ensure the file conforms to the properties DTD and uses UTF-8 encoding.

```xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE properties SYSTEM "http://java.sun.com/dtd/properties.dtd">
<properties>
	<entry key="greetingMessage">欢迎光临本网站！</entry>
</properties>
```

--------------------------------

### Build Docker Image

Source: https://github.com/apache/wicket/blob/master/wicket-examples/docker-howto.md

Builds the Docker image for Wicket examples and tags it with the specified version.

```bash
docker build --tag apache.jfrog.io/wicket-docker/wicket-examples:LATEST-10 .
```

--------------------------------

### Install Wicket feature in Karaf

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/karaf/karaf_1.adoc

Install the 'wicket-core' feature into your running Karaf instance. This makes Wicket available for use.

```bash
karaf@root()> feature:install wicket-core
```

--------------------------------

### Basic Wicket Page Rendering Test

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/testing/testing_1.adoc

This snippet demonstrates the fundamental setup for Wicket unit testing. It initializes WicketTester and asserts that the home page renders successfully without errors. Use this as a starting point for most Wicket tests.

```java
class TestHomePage{
	private WicketTester tester;

	@BeforeEach
	void setUp(){
		tester = new WicketTester(new WicketApplication());
	}
	@Test
	void homepageRendersSuccessfully(){
		//start and render the test page
		tester.startPage(HomePage.class);
		//assert rendered page class
		tester.assertRenderedPage(HomePage.class);
	}
}
```

--------------------------------

### Static Label Example

Source: https://github.com/apache/wicket/blob/master/wicket-examples/src/main/java/org/apache/wicket/examples/compref/LabelPage.html

Displays static text directly on the page. This is the simplest form of a label.

```html
this text will be replaced
```

--------------------------------

### Launch JNLP Application with JavaScript

Source: https://github.com/apache/wicket/blob/master/wicket-core-tests/src/test/java/org/apache/wicket/markup/MarkupParserTest_7.html

This script launches a JNLP application. It checks for Gecko-based browsers or if Java Web Start is installed to determine the launch method. If neither condition is met, it provides instructions to download and install the JRE.

```javascript
//<![CDATA[
// /* Note that the logic below always launches the JNLP application
// * if the browser is Gecko based. This is because it is not possible
// * to detect MIME type application/x-java-jnlp-file on Gecko-based browsers.
// */
var javawsInstalled=true;
if (javawsInstalled || (navigator.userAgent.indexOf("Gecko") !=-1)) {
    document.write("<a href=http://localhost:8084/app.jnlp>Launch the application</a>");
} else {
    document.write("Click ");
    document.write("<a href=http://java.sun.com/PluginBrowserCheck?pass=http://localhost:8084/AutoInstallJRE.html&fail=http://java.sun.com/j2se/1.5.0/download.html>here</a> ");
    document.write("to download and install JRE 5.0 and the application.");
}
// it mustnt break if the string contains the cdata end marker ]]
var test1="some]]>"; //]]>
```

--------------------------------

### Example URL for a Package-Mounted Page

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/urls/urls_6.adoc

Demonstrates the URL structure for a specific page within a package that has been mounted. The URL includes the base mounted path and the page's class name.

```html
<Application path>/mountPackage/StatefulPackageMount?1
```

--------------------------------

### Configure Wicket Deployment Mode via System Property

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/maven/maven_1.adoc

Set Wicket to run in deployment mode by specifying the system property '-Dwicket.configuration=deployment' when starting the server.

```java
java -Dwicket.configuration=deployment ...
```

--------------------------------

### Verify Wicket feature installation in Karaf

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/karaf/karaf_1.adoc

Check if the Wicket feature is available in your Karaf environment. This command lists all installed features and filters for 'wicket'.

```bash
karaf@root()> feature:list | grep -i wicket
wicket-core    │ _version_ │    │ Uninstalled │ org.apache.wicket.wicket-_version_ │
```

--------------------------------

### Set and Get Indexed PageParameters

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/urls/urls_1.adoc

Demonstrates how to set indexed parameters and retrieve their values using PageParameters.

```java
PageParameters pageParameters = new PageParameters(); 
//add a couple of parameters
pageParameters.set(0, "foo");
pageParameters.set(1, "bar");
//retrieve the value of the second parameter ("bar")
pageParameters.get(1);
```

--------------------------------

### Bookmarkable URL with Named Parameters

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/urls/urls_1.adoc

Example of a generated bookmarkable URL that includes named query string parameters.

```html
<app root>/PageParametersExample/wicket/bookmarkable/
		org.wicketTutorial.PageWithParameters?foo=foo&bar=bar
```

--------------------------------

### Wicket Component Queuing Example

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/componentQueueing/componentQueueing_4.adoc

Demonstrates how to queue components in Wicket, including nested components within a container. Ensure components are queued to their intended parent or ancestor to maintain security and structure.

```java
queue(new Label("first"));
queue(new Label("last"));

WebMarkupContainer secure=new WebMarkupContainer("secure") {
    void onConfigure() {
       super.onConfigure();
       setVisible(isViewingOwnProfile());
    }
};

queue(secure);
secure.queue(new Label("creditCardNumber"));
secure.queue(new Label("creditCardExpiry"));
```

--------------------------------

### HTML Markup for List/Detail View Page

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/modelsforms/modelsforms_6.adoc

This is the HTML structure for the example page, defining a dropdown for persons and a form for editing their details.

```html
<body>
  List of persons <select wicket:id="persons"></select> <br/>
  <br/>
  <form wicket:id="form">
    <div style="display: table;">
      <div style="display: table-row;">
        <div style="display: table-cell;">Name: </div>
        <div style="display: table-cell;">
          <input type="text" wicket:id="name"/>
        </div>
      </div>
      <div style="display: table-row;">
        <div style="display: table-cell;">Surname: </div>
        <div style="display: table-cell;">
          <input type="text" wicket:id="surname"/>
        </div>
      </div>
        <div style="display: table-row;">
        <div style="display: table-cell;">Address: </div>
        <div style="display: table-cell;">
          <input type="text" wicket:id="address"/>
        </div>
      </div>
      <div style="display: table-row;">
        <div style="display: table-cell;">Email: </div>
        <div style="display: table-cell;">
          <input type="text" wicket:id="email"/>
        </div>
      </div>
    </div>
    <input type="submit" value="Save"/>
  </form>
</body>
```

--------------------------------

### Basic Link Example

Source: https://github.com/apache/wicket/blob/master/wicket-examples/src/main/java/org/apache/wicket/examples/compref/LinkPage.html

Demonstrates a basic Wicket link attached to an anchor element. This is used for standard navigation or triggering actions.

```html
[this link is clicked n times](#)
```

--------------------------------

### Get and Set Resource Stream Locator

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/resources/resources_14.adoc

Demonstrates how to retrieve the current resource locator and set a custom one using ResourceSettings. This is typically done during application initialization.

```java
  //init application's method
  @Override
  public void init(){
    //get the resource locator
    getResourceSettings().getResourceStreamLocator();
    //set the resource locator
    getResourceSettings().setResourceStreamLocator(myLocator);
  }
```

--------------------------------

### Inspect Wicket feature details in Karaf

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/karaf/karaf_1.adoc

Use this command to get detailed information about the 'wicket-core' feature, including its bundles and dependencies. This is useful for troubleshooting.

```bash
karaf@root()> feature:info wicket-core
Feature wicket-core _version_
Feature has no configuration
Feature has no configuration files
Feature has no dependencies.
Feature contains followed bundles:
  ... _wicket dependency bundles_ ...
  mvn:org.apache.wicket/wicket-util/_version_
  mvn:org.apache.wicket/wicket-request/_version_
  mvn:org.apache.wicket/wicket-core/_version_
  mvn:org.apache.wicket/wicket-auth-roles/_version_
  mvn:org.apache.wicket/wicket-devutils/_version_
  mvn:org.apache.wicket/wicket-extensions/_version_
  mvn:org.apache.wicket/wicket-jmx/_version_
Feature has no conditionals.
```

--------------------------------

### JavaScript Module Imports

Source: https://github.com/apache/wicket/blob/master/wicket-core-tests/src/test/java/org/apache/wicket/markup/parser/filter/PageWithScriptTemplate.html

Example of how to define module imports for JavaScript, specifying local and remote module paths.

```javascript
{ "imports": { "square": "./module/shapes/square.js", "circle": "https://example.com/shapes/circle.js" } }
```

--------------------------------

### Generated URL with Placeholder

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/urls/urls_6.adoc

Example of a generated URL when using a parameter placeholder. The placeholder value is inserted into the URL path.

```html
<Application path>/pageMount/foo/otherSegm
```

--------------------------------

### Wicket ID Naming Example

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/bestpractices/bestpractices_3.adoc

Demonstrates correct Wicket ID naming by including only the business aspect. This avoids redundancy with technical details present in both HTML and Java code.

```java
new TextField("birthdate")
```

--------------------------------

### Bad Practice: Passing Page to Constructor

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/bestpractices/bestpractices_10.adoc

Avoid passing entire components or pages to constructors. This example shows a 'SettingsPage' that accepts a 'backToPage' argument, leading to tight coupling and predetermined instantiation order.

```java
// Bad solution
public class SettingsPage extends Page {
    public SettingsPage (IModel<Settings> settingsModel, final Webpage backToPage) {
        Form<?> form = new Form("form");
        // add components
        form.add(new SubmitButton("changeSettings") {
            public void onSubmit() {
               // do something
               setResponsePage(backToPage);
            }
        });
        add(form);
    }
}
```

--------------------------------

### Wicket Component Factory Pattern Example

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/bestpractices/bestpractices_12.adoc

Demonstrates a factory pattern for creating Wicket Label components. This approach has limitations regarding inheritance and overriding component lifecycle methods.

```java
public class CmsFactory {
   public Label getCmsLabel(String markupId, final String url) {
       IModel<String> fragment = () -> loadSomeContent(url);
       Label result = new Label(markupId, fragment);
       result.setRenderBodyOnly(true);
       result.setEscapeModelStrings(false);
       return result;
   }

   public String loadContent(String url) {
      // load some content
   }
}

// create the component within the page:
public class MyPage extends WebPage {
   @SpringBean
   CmsFactory cmsFactory;

   public MyPage() {
      add(cmsFactory.getCmsLabel("id", "http://url.to.load.from"));
   }
}
```

--------------------------------

### Original Wicket Java Hierarchy

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/componentQueueing/componentQueueing_1.adoc

This Java code represents the initial setup of Wicket components before introducing a new container.

```java
Form<Void> form = new Form<>("customer");
add(form);

form.add(new TextField("first"));
form.add(new TextField("last"));
```

--------------------------------

### StatelessLink Example with Instance Variable

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/urls/urls_5.adoc

Illustrates a potential issue where instance variables in onClick() of a StatelessLink may not behave as expected due to page re-instantiation. The printed value will always be zero.

```java
public class StatelessPage extends WebPage {
	private int index = 0;

	public StatelessPage(PageParameters parameters) {
		super(parameters);
	}
	
	@Override
	protected void onInitialize() {
		super.onInitialize();
		setStatelessHint(true);
		
		add(new StatelessLink("statelessLink") {

			@Override
			public void onClick() {
				//It will always print zero
				System.out.println(index++);
			}
		
		});
	}	
}
```

--------------------------------

### Mount Resource Reference with Lambda Supplier

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/resources/resources_12.adoc

Lambda expressions are useful with ResourceReference factory methods like 'of' that accept a resource supplier. This example shows how to mount a resource defined by a lambda.

```java
@Override
public void init() {
  super.init();

  IResource helloWorldRes = (attributes) -> 
     attributes.getResponse().write("Hello world!");
     
  ResourceReference resRef = ResourceReference.of("helloworld", () -> helloWorldRes);        

  mountResource("/helloworld", resRef);
}
```

--------------------------------

### Model-Bound Visibility Control

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/bestpractices/bestpractices_5.adoc

Configure component visibility based on its model's state. This example makes a Label visible only if its text starts with 'Berlusconi'.

```java
new Label("headline", headlineModel) {
    @Override
    public void onConfigure() {
        // Headline visible only if text starts with "Berlusconi"
        String headline = getModelObject();
        setVisible(headline.startsWith("Berlusconi"));
    }
}
```

--------------------------------

### Basic REST Resource Implementation

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/wicketstuff/wicketstuff_6.adoc

Demonstrates mapping methods to specific subpaths and HTTP methods using @MethodMapping.

```APIDOC
## GET /persons

### Description
Retrieves a list of all persons.

### Method
GET

### Endpoint
/persons

### Request Body
None

### Response
#### Success Response (200)
- **List<PersonPojo>** (List) - A list of PersonPojo objects.

#### Response Example
```json
[
  {
    "name": "John Doe",
    "age": 30
  }
]
```

## DELETE /persons/{personIndex}

### Description
Deletes a person identified by their index.

### Method
DELETE

### Endpoint
/persons/{personIndex}

### Parameters
#### Path Parameters
- **personIndex** (int) - Required - The index of the person to delete.

### Response
#### Success Response (200)
- No content is returned upon successful deletion.

## POST /persons

### Description
Creates a new person resource.

### Method
POST

### Endpoint
/persons

### Request Body
- **personPojo** (PersonPojo) - Required - The data for the new person.

### Request Example
```json
{
  "name": "Jane Doe",
  "age": 25
}
```

### Response
#### Success Response (200)
- No content is returned upon successful creation.

```

--------------------------------

### Wicket AJAX JavaScript Call Example

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/ajax/ajax_5.adoc

This is an example of the final AJAX function generated for a behavior used in the AjaxEventBehavior project. It shows the parameters passed to Wicket.Ajax.ajax.

```javascript
Wicket.Ajax.ajax({"u":"./?0-1.IBehaviorListener.0-clickCounterLabel", "e":"click",               
                  "c":"clickCounterLabel1"});
```

--------------------------------

### Setup DropDownChoice with Localized Display Values in Wicket

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/i18n/i18n_4.adoc

Override localizeDisplayValues to return true to enable localization of choice display values. This setup is for a DropDownChoice component that displays colors.

```java
public HomePage(final PageParameters parameters) {
	super(parameters);

	List<Locale> locales = Arrays.asList(Locale.ENGLISH, Locale.ITALIAN, Locale.GERMAN);
	List<String> colors = Arrays.asList("green", "red", "blue", "yellow");
		
	final DropDownChoice<Locale> changeLocale = new DropDownChoice<Locale>("changeLocale", 
                                                    new Model<Locale>(), locales);
		
	StatelessForm<Void> form = new StatelessForm<Void>("form"){
		@Override
		protected void onSubmit() {
			Session.get().setLocale(changeLocale.getModelObject());
		}
	};		
		
	DropDownChoice<String> selectColor = new DropDownChoice<String>("selectColor", new 
                                                            Model<String>(), colors){
		@Override
		protected boolean localizeDisplayValues() {
			return true;
		}
	};
		
	form.add(selectColor);
	add(form.add(changeLocale));
    }
```

--------------------------------

### Using DataGrid with ListDataProvider

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/wicketstuff/wicketstuff_5.adoc

Illustrates how to instantiate and configure a DataGrid component using a ListDataProvider and defining columns. Ensure the Person list is loaded before creating the ListDataProvider.

```html
...
  <div wicket:id="grid">Grid</div>
...
```

```java
final List<Person> personList = //load a list of Persons
final ListDataProvider listDataProvider = new ListDataProvider(personList);
//define grid's columns
List<IGridColumn> cols = (List) Arrays.asList(
     new PropertyColumn(new Model("First Name"), "firstName"),
     new PropertyColumn(new Model("Last Name"), "lastName"));

DataGrid grid = new DefaultDataGrid("grid", new DataProviderAdapter(listDataProvider), cols);
add(grid);
```

--------------------------------

### Declare JavaScript and CSS Resource Bundles

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/resources/resources_7.adoc

Initialize resource bundles for JavaScript and CSS during application startup. Ensure each resource reference is unique to a single bundle.

```java
getResourceBundles().addJavaScriptBundle(WicketApplication.class,
                "jqueryUiJs",
                jqueryJsReference,
                jqueryUiJsReference);
 
 getResourceBundles().addCssBundle(WicketApplication.class,
                 "jqueryUiCss",
                jqueryCssReference,
                jqueryUiCssReference);
```

--------------------------------

### Wicket Model Inheritance Pitfall Example

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/modelsforms/modelsforms_4.adoc

This example demonstrates a potential pitfall with CompoundPropertyModel where nested containers without their own models can lead to unexpected property expressions. The 'name' label inherits the page's model, but the 'spouse' container's ID is ignored in the property expression.

```java
//Create a person named 'John Smith'
Person person = new Person("John", "Smith");
//Create a person named 'Jill Smith'
Person spouse = new Person("Jill", "Smith");
//Set Jill as John's spouse
person.setSpouse(spouse);

defaultModel(new CompoundPropertyModel(person));
WebMarkupContainer spouseContainer = new WebMarkupContainer("spouse");
Label name;
spouseContainer.add(name = new Label("name"));

add(spouseContainer);
```

--------------------------------

### HTML Markup for Label Example

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/componentLifecycle/componentLifecycle_4.adoc

The associated HTML markup for the Label component that will be modified by onComponentTag.

```html
<head>
  <meta charset="utf-8" />
  <title></title>
</head>
<body>
  <h1 wicket:id="helloMessage"></h1>
</body>
```

--------------------------------

### Simulating Link Clicks and Asserting Label Text

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/testing/testing_1.adoc

This example shows how to simulate a user clicking a link and then verify that a specific label's text has updated as expected. It uses `clickLink` to trigger an action and `assertLabel` to check the result. Ensure the component paths are correct for your application.

```java
//... 
@Test
void switchLabelTest(){
	//start and render the test page
	tester.startPage(HomePage.class);
	//assert rendered page class
	tester.assertRenderedPage(HomePage.class);
	//assert rendered label
	tester.assertLabel("label", "First label");
	//simulate a click on "reload" button
	tester.clickLink("reload");
	//assert rendered label
	tester.assertLabel("label", "Second label");
}
//...
```

--------------------------------

### Good Practice: Using a Hook for Navigation

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/bestpractices/bestpractices_10.adoc

This solution uses the Hollywood principle by introducing an abstract method 'onSettingsChanged()' as a hook. This decouples the 'SettingsPage' from the specific page it redirects to, improving flexibility and reusability.

```java
// Good solution
public class SettingsPage extends Page {
    public SettingsPage (IModel<Settings> settingsModel) {
        Form<?> form = new Form("form");
        // add components
        form.add(new SubmitButton("changeSettings") {
            public void onSubmit() {
               // do something
               onSettingsChanged();
            }
         });
         add(form);
    }

    // hook
    protected void onSettingsChanged() {
    }

// The usage of the new component
Link<Void> settings = new Link<Void>("settings") {
    public void onClick() {
        setResponsePage(new SettingsPage(settingsModel) {
            @Override
            protected void onSettingsChanged() {
               // reference to the current page
               setResponsePage(this);
            }
        });
    }
};
add(settings);
```

--------------------------------

### Wicket Enclosure Markup

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/componentQueueing/componentQueueing_2.adoc

Example of Wicket markup using the 'enclosure' attribute to group components.

```xml
<wicket:enclosure childId="first">
    <input wicket:id="first" type="text"/>
    <input wicket:id="last" type="text"/>
</wicket:enclosure>
```

--------------------------------

### Autonomous Component Visibility with onConfigure()

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/bestpractices/bestpractices_5.adoc

Use the onConfigure() method to allow components to manage their own visibility. This approach centralizes logic and avoids manual state management, making it more robust.

```java
public class LoginBoxPanel {
    // constructor etc.
    @Override
    public void onConfigure() {
        setVisible(MySession.get().isNotLoggedIn());
    }
}
```

--------------------------------

### Initialize Wicket HTTP/2 Settings with Custom PushBuilder

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/http2push/http2push_2.adoc

This Initializer class sets up Wicket's HTTP/2 settings by providing a custom PushBuilder implementation. Ensure this class is correctly registered in META-INF/services/org.apache.wicket.IInitializer.

```java
public class Initializer implements IInitializer
{
	/**
	 * Initializes the push builder API of Jetty 9.3+
	 */
	@Override
	public void init(Application application)
	{
		Http2Settings http2Settings = Http2Settings.Holder.get(application);
		http2Settings.setPushBuilder(new Jetty9PushBuilder());
	}

	@Override
	public void destroy(Application application)
	{
		// NOOP
	}
}
```

--------------------------------

### Create a Main Initializer to Orchestrate Others

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/advanced/advanced_4.adoc

Use a main initializer to call the init methods of other initializers, allowing for multiple configurations.

```java
public class MainInitializer implements IInitializer{

	public void init(Application application) {
		new AnotherInitializer().init(application);
		new YetAnotherInitializer().init(application);
		//... 
	}
	//destroy...
}
```

--------------------------------

### HTML Markup for Wicket Component

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/keepControl/keepControl_8.adoc

This is the example HTML markup that includes a Wicket component with the `wicket:id` attribute.

```html
<html>
<head>
  <title>Hello world page</title>
</head>
<body>
<div wicket:id="helloWorld">[helloWorld]</div>
</body>
</html>
```

--------------------------------

### Append JavaScript via AJAX

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/ajax/ajax_1.adoc

Appends custom JavaScript code to the AJAX response, for example, to display an alert box.

```java
new AjaxLink<Void>("ajaxLink"){
	@Override
	public void onClick(AjaxRequestTarget target) {
	    target.appendJavaScript(";alert('Hello!!');");
	}
};
```

--------------------------------

### Get Required WebApplicationContext

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/testingspring/testingspring_2.adoc

Retrieves the WebApplicationContext from the ServletContext. Throws an IllegalStateException if no context is found, typically indicating a missing ContextLoaderListener.

```java
public static WebApplicationContext getRequiredWebApplicationContext(ServletContext sc)
		throws IllegalStateException {

	WebApplicationContext wac = getWebApplicationContext(sc);
	if (wac == null) {
		throw new IllegalStateException("No WebApplicationContext found: no ContextLoaderListener registered?");
	}
	return wac;
}
```

--------------------------------

### Configure Wicket Deployment Mode via Context Parameter

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/maven/maven_1.adoc

Set Wicket to run in deployment mode by defining a context parameter named 'configuration' with the value 'deployment'.

```html
<context-param>
    <param-name>configuration</param-name>
    <param-value>deployment</param-value>
</context-param>
```

--------------------------------

### Generated URL with Encoded Parameters

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/urls/urls_6.adoc

Example of a generated URL showing how page parameters are encoded as URL segments when using UrlPathPageParametersEncoder.

```html
<Application path>/mountedPath/foo/foo/bar/bar?1
```

--------------------------------

### Configure Basic Video Settings in Wicket

Source: https://github.com/apache/wicket/blob/master/wicket-examples/src/main/java/org/apache/wicket/examples/media/Home.html

Use this to set autoplay, controls, looping, and dimensions for a video. The width and height are null by default. Set readBuffered(false) to avoid storing the media file in memory.

```java
PackageResourceReference reference = new PackageResourceReference(MyPage.class, "myVideo.mp4");
Video video = new Video("myVideo", reference);
video.setAutoplay(false);
video.setControls(true);
video.setLooping(false);
video.setWidth(320);
video.setHeight(240);
video.setBuffered(false);
```

--------------------------------

### Adding DisableComponentListener to AjaxButton

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/ajax/ajax_6.adoc

Example of how to add a custom DisableComponentListener to an AjaxButton's attributes to manage component state during AJAX calls.

```java
//...
new AjaxButton("ajaxButton"){
	@Override
	protected void updateAjaxAttributes(AjaxRequestAttributes attributes) {
	  super.updateAjaxAttributes(attributes);
	  attributes.getAjaxCallListeners().add(new DisableComponentListener(form));
	}
}
//...
```

--------------------------------

### Configure Picture Component with Sources and Fallback

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/resources/resources_3.adoc

Use the Picture component to provide responsive images with multiple sources and a fallback image. Configure Source components with resource references and media attributes.

```java
Picture picture = new Picture("picture");

Source big = new Source("big", new PackageResourceReference(getClass(), "big.jpg"), new PackageResourceReference(getClass(), "big-hd.jpg"));
big.setXValues("1x","2x");
big.setMedia("(min-width: 40em)");
picture.add(big);

Source small = new Source("small", new PackageResourceReference(getClass(), "small.jpg"), new PackageResourceReference(getClass(), "small-hd.jpg"));
small.setXValues("1x","2x");
picture.add(small);

Image image = new Image("fallback", new PackageResourceReference(getClass(), "fallback.jpg"));
picture.add(image);

this.add(picture);
```

--------------------------------

### Basic AJAX Link onClick

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/ajax/ajax_1.adoc

An example of an AjaxLink's onClick method, which is executed on AJAX request. Requires an instance of AjaxRequestTarget.

```java
new AjaxLink<Void>("ajaxLink"){
	@Override
	public void onClick(AjaxRequestTarget target) {
	    //some server side code...
	}
};
```

--------------------------------

### Registering a Custom Crypt Factory

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/security/security_4.adoc

Demonstrates how to set a custom ICryptFactory at the application level using SecuritySettings. This is useful for integrating stronger or different cryptography mechanisms.

```java
@Override
public void init() {
	super.init();
	getSecuritySettings().setCryptFactory(new SomeCryptFactory());
	setRootRequestMapper(new CryptoMapper(getRootRequestMapper(), this));
}
```

--------------------------------

### Execute Wicket Ajax Request

Source: https://github.com/apache/wicket/blob/master/wicket-core-tests/src/test/java/org/apache/wicket/ajax/DomReadyOrderPage_ajax_expected.html

Initiates a Wicket Ajax request. This example triggers a 'click' event on an element with ID 'test1'.

```javascript
(function(){Wicket.Ajax.ajax({"u":"./org.apache.wicket.ajax.DomReadyOrderPage?0-1.0-test","c":"test1","e":"click","pd":true});})();
```

--------------------------------

### WicketStuff Module Structure

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/wicketstuff/wicketstuff_1.adoc

Illustrates the typical directory structure of a WicketStuff module, consisting of a parent project, the main module, and an example module.

```text
<module name>-parent
        |
        +---<module name>
        \---<module name>-examples
```

--------------------------------

### Structure BlogEditPage Component in Java

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/bestpractices/bestpractices_15.adoc

Example of structuring a Wicket page by extracting form elements into separate methods. This promotes modularity and readability.

```java
public class BlogEditPage extends WebPage {
    private IModel<Blog> blogModel;

    public BlogEditPage(IModel<Blog> blogModel) {
        super(new PageParameters());
        this.blogModel = blogModel;
        add(createBlogEditForm());
    }

    private Form<Blog> createBlogEditForm() {
        Form<Blog> form = newBlogEditForm();
        form.add(createHeadlineField());
        form.add(createContentField());
        form.add(createTagField());
        form.add(createViewRightPanel());
        form.add(createCommentRightPanel());
        form.setOutputMarkupId(true);
        return form;
    }

    // more methods here
}
```

--------------------------------

### Configure Video with Source Tags and Media Queries in Wicket

Source: https://github.com/apache/wicket/blob/master/wicket-examples/src/main/java/org/apache/wicket/examples/media/Home.html

Add multiple source tags to a video and apply media queries to display different videos based on screen resolution. This allows for responsive video delivery.

```java
PackageResourceReference reference1 = new PackageResourceReference(MyPage.class, "video_small.mp4");
Source source1 = new Source(reference1);
source1.setMedia("(max-width: 600px)");

PackageResourceReference reference2 = new PackageResourceReference(MyPage.class, "video_large.mp4");
Source source2 = new Source(reference2);
source2.setMedia("(min-width: 601px)");

Video video = new Video("myVideo", source1, source2);
video.setControls(true);
```

--------------------------------

### Trigger Deferred Ajax Request

Source: https://github.com/apache/wicket/blob/master/wicket-core-tests/src/test/java/org/apache/wicket/markup/head/filter/DeferredPage_AjaxExpected.html

Initiates an Ajax request to the server for deferred rendering. This example shows a click event triggering the request.

```javascript
(function(){
Wicket.Ajax.ajax({"u":"./page?0-1.0-c","c":"c1","e":"click"});
})();
```

--------------------------------

### Get Application Metadata (Java)

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/requestProcessing/requestProcessing_4.adoc

Retrieves a previously stored java.sql.Connection object from the application's metadata store using its specific MetaDataKey.

```java
Connection connection = Application.get().getMetaData(MetaDataApp.connectionKey);
```

--------------------------------

### Get Current RequestCycle in Wicket Component

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/requestProcessing/requestProcessing_3.adoc

A convenience method within a Wicket Component to retrieve the current RequestCycle. It internally calls RequestCycle.get().

```java
public final RequestCycle getRequestCycle() {
	return RequestCycle.get();
}
```

--------------------------------

### Wicket Component Hierarchy Solution

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/componentQueueing/componentQueueing_2.adoc

Shows how using 'queue' instead of 'add' correctly inserts auto components into the Java hierarchy, resolving visibility and validation issues.

```java
queue(new TextField("first").setRequired(true).setVisible(false));
queue(new TextField("last").setRequired(true));
```

--------------------------------

### Generated URL with Missing Optional Placeholder

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/urls/urls_6.adoc

Example of a generated URL when an optional parameter is missing. The URL segment corresponding to the optional placeholder is omitted.

```html
<Application path>/pageMount/otherSegm
```

--------------------------------

### Mount Page with Parameter Placeholder

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/urls/urls_6.adoc

Define a URL path with a dynamic segment using ${placeholderName}. This segment will be populated by the named parameter when the page is instantiated.

```java
mountPage("/pageMount/${foo}/otherSegm", MountedPageWithPlaceholder.class);
```

--------------------------------

### Create ResourceModel with Key

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/i18n/i18n_5.adoc

Use ResourceModel to retrieve a string resource based on a given key. This is suitable for simple, static resource lookups.

```java
new ResourceModel("greetingMessage");
```

--------------------------------

### Implement Single Checkbox Form in Wicket

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/forms2/forms2_11.adoc

This example demonstrates how to create a form with a single CheckBox component, linking it to a boolean property in a model object.

```html
<form wicket:id="form">
		<div style="display: table;">
			<div style="display: table-row;">
				<div style="display: table-cell;">Name: </div>
				<div style="display: table-cell;">
					<input type="text" wicket:id="name"/>
				</div>
			</div>
			<div style="display: table-row;">
				<div style="display: table-cell;">Surname: </div>
				<div style="display: table-cell;">
					<input type="text" wicket:id="surname"/>
				</div>
			</div>
			<div style="display: table-row;">
				<div style="display: table-cell;">Address: </div>
				<div style="display: table-cell;">
					<input type="text" wicket:id="address"/>
				</div>
			</div>
			<div style="display: table-row;">
				<div style="display: table-cell;">Email: </div>
				<div style="display: table-cell;">
					<input type="text" wicket:id="email"/>
				</div>
			</div>
			<div style="display: table-row;">
				<div style="display: table-cell;">Subscribe list:</div>
				<div style="display: table-cell;">
					<input type="checkbox" wicket:id="subscribeList"/>
				</div>
			</div>
		</div>
	<input type="submit" value="Save"/>
</form>
```

```java
public HomePage(final PageParameters parameters) {
    RegistrationInfo registrationInfo = new RegistrationInfo();
    registrtionInfo.setSubscribeList(true);

    Form<Void> form = new Form<>("form",
    			new CompoundPropertyModel<RegistrationInfo>(registrtionInfo));

    form.add(new TextField("name"));
	form.add(new TextField("surname"));
	form.add(new TextField("address"));
	form.add(new TextField("email"));
	form.add(new CheckBox("subscribeList"));

	add(form);
}
```

--------------------------------

### Timed Ajax Update for Component

Source: https://github.com/apache/wicket/blob/master/wicket-core-tests/src/test/java/org/apache/wicket/ajax/markup/html/componentMap/SimpleTestPageExpectedResult.html

Initiates a timed Ajax update for a specific Wicket component. This example updates the component every 2 seconds.

```javascript
Wicket.Event.add(window, "load", function(event) { Wicket.Timer.set('linja11.0', function(){Wicket.Ajax.ajax({"u":"./org.apache.wicket.ajax.markup.html.componentMap.SimpleTestPage?0-1.0-testPanel-baseSpan-linja1","c":"linja11"});}, 2000);; ;});
```

--------------------------------

### StringResourceModel with Component and Model

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/i18n/i18n_5.adoc

Instantiate StringResourceModel specifying the resource key, a component for bundle lookup, and a model for dynamic data. This allows for custom bundle selection.

```java
new StringResourceModel("myKey", myComponent, myModel);
```

--------------------------------

### Java Code for WebMarkupContainer

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/keepControl/keepControl_4.adoc

This Java code demonstrates initializing a WebMarkupContainer, adding a Label to it, and managing its visibility. Use this for components that are tightly coupled to a specific page's markup.

```java
//Page initialization code
WebMarkupContainer informationBox = new WebMarkupContainer ("informationBox");
informationBox.add(new Label("messagesNumber", messagesNumber));
add(informationBox);

//If there are no new messages, hide informationBox
informationBox.setVisible(false);
```

--------------------------------

### Trigger Wicket Ajax Request

Source: https://github.com/apache/wicket/blob/master/wicket-core-tests/src/test/java/org/apache/wicket/TestDetachPageAjaxResult.html

Initiates an AJAX request using Wicket's JavaScript API. This example triggers a click event on a component.

```javascript
(function(){Wicket.Ajax.ajax({"u":"./org.apache.wicket.TestDetachPage?0-1.0-comp","c":"comp1","e":"click"});})();
```

--------------------------------

### Implement Wicket IInitializer Interface

Source: https://github.com/apache/wicket/blob/master/wicket-user-guide/src/main/asciidoc/advanced/advanced_4.adoc

Implement the init(Application) method for initialization code and destroy(Application) for cleanup when the application terminates.

```java
public class MyInitializer implements IInitializer{

	public void init(Application application) {
		//initialization code 
	}

	public void destroy(Application application) {
		//code to execute when application is terminated
	}	
}
```