ActionLink (Tapestry API Documentation)

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org.apache.tapestry5.corelib.components
Class ActionLink

java.lang.Object
  org.apache.tapestry5.corelib.base.AbstractLink
      org.apache.tapestry5.corelib.base.AbstractComponentEventLink
          org.apache.tapestry5.corelib.components.ActionLink

All Implemented Interfaces:: ClientElement

@Events(value="action") public class ActionLink
extends AbstractComponentEventLink
extends AbstractComponentEventLink

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

Component Parameters
Name	Description	Type	Flags	Default	Default Prefix	Since
anchor	An anchor value to append to the generated URL (the hash separator will be added automatically).	String			literal
context	The 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.	Object			prop
disabled	If true, then then no link element is rendered (and no informal parameters as well). The body is, however, still rendered.	boolean		false	prop
parameters	If specified, the parameters are added to the link as query parameters in key=value fashion. Values will be coerced to string using value encoder; keys should be Strings.	java.util.Map	Not Null		prop	5.3
zone	Binding the zone parameter turns the link into a an Ajax control that causes the related zone to be updated.	String			literal

Events:

action

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
{
    public long id;

    public String userName;
    
}

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:

You can do this in a template using the following syntax:

<t:actionlink t:id="delete" context="[account.companyId, account.id]">delete ${company.name} / ${account.id}</t:actionlink>

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

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

        return accountsSummaryPage;
    }

Alternatively, you can provide a getter which returns an object array.

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

In the template, this would be referenced as:

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

This pattern was more common in early versions of Tapestry; the older versions of the property expression language did not have the ability to create an array on the fly.

Constructor Summary
`ActionLink()`

Method Summary
`protected Link`	`createLink(Object[] contextArray)` Invoked to create the Link that will become the href attribute of the output.

Methods inherited from class org.apache.tapestry5.corelib.base.AbstractLink
`addParameters, getClientId, getLink, isDisabled, writeLink`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

ActionLink

public ActionLink()

Method Detail

createLink

protected Link createLink(Object[] contextArray)

Description copied from class: AbstractComponentEventLink

Invoked to create the Link that will become the href attribute of the output.

Specified by:: createLink in class AbstractComponentEventLink

Parameters:: contextArray - the context as an object array, possibly null