org.apache.tapestry5.corelib.components.ActionLink

Component that triggers an action on the server with a subsequent full page refresh.

[JavaDoc]

Component Inheritance

Component Parameters

NameTypeFlagsDefaultDefault PrefixDescription
anchorStringNOT Allow NullliteralAn anchor value to append to the generated URL (the hash separator will be added automatically).
contextObjectNOT Allow NullpropThe context for the link (optional parameter). This list of values will be converted into strings and included in the URI. The strings will be coerced back to whatever their values are and made available to event handler methods.
disabledbooleanNOT Allow NullfalsepropIf true, then then no link element is rendered (and no informal parameters as well). The body is, however, still rendered.
zoneStringNOT Allow NullliteralBinding the zone parameter turns the link into a an Ajax control that causes the related zone to be updated.

Examples

In this example, we are showing part of a page to view and Account object, with an option to delete the Account.

Account.java

public class Account
{
    private long id;

    private String userName;

    // etc., etc., ...

    // Getters and setters omitted ...
    
}

ViewAccount.tml

<html xmlns:t="http://tapestry.apache.org/schema/tapestry_5_0_0.xsd">
    <body>
        <h1>View Account #${account.id}</h1>

        <t:beandisplay object="account"/>

        <p>
          [<t:actionlink t:id="delete" context="account.id">delete</t:actionlink>
        </p>
    </body>
</html>
We store the account's id as event context inside the URL. The account's id will be part of the URL and will be accessible when the event request is later triggered.

ViewAccount.java

public class ViewAccount
{
    @Persist
    private Account account;

    @InjectPage
    private AccountsSummary accountsSummaryPage;

    @Inject
    private AccountDAO accountDAO;

    public Account getAccount() { return account; }

    Object onActionFromDelete(long accountId)
    {
        accountDAO.delete(accountId);

        accountsSummaryPage.setMessage(String.format("Account #%d has been deleted.", accountId));

        return accountsSummaryPage;
    }
}
The ActionLink component triggers an "action" event, which is matched by the onActionFromDelete() method. A real application might have other action links on the page, for (say) creating new accounts or other operations, thus we use the component's id ("delete") to ensure that the method is only invoked under the expected circumstances.

Notice how the context (from when the link was rendered) now becomes parameters to the event handler method.

The AccountDAO (data access object) service is responsible for the work, we then set a message on another page (the field for this message should be persistent) and return the page. Tapestry will send a redirect request to the client to display the page.

Notes

Rarely, you might need to pass more information in the context. For example, perhaps account id is not enought to uniquely identify the Account object in question - hypothetically, you may need to include a company id as well as the account id. You can build an object array to contain both values: 

    public Object[] getAccountContext()
    {
        return new Object[] { account.companyId, account.id };
    }

    Object onActionFromDelete(long companyId, long accountId)
    {
        accountDAO.delete(companyId, accountId);

        accountsSummaryPage.setMessage(String.format("Account #%d has been deleted.", accountId));

        return accountsSummaryPage;
    }

In the template, this would be referenced as: 

        <p>
          [<t:actionlink t:id="delete" context="accountContext">delete</t:actionlink>
        </p>

This highlights the use of the component class: any complicated processing should be offloaded out of the template and into the class.

Back to index