| <document> |
| <body> |
| |
| <section name="Examples"> |
| |
| <p> |
| In this example, we are showing part of a page to view and Account object, with an option to |
| delete the Account. |
| </p> |
| |
| |
| <subsection name="Account.java"> |
| <source><![CDATA[ |
| public class Account |
| { |
| public long id; |
| |
| public String userName; |
| |
| }]]></source> |
| </subsection> |
| |
| <subsection name="ViewAccount.tml"> |
| <source><![CDATA[ |
| <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> |
| ]]></source> |
| |
| <p> |
| We store the account's id as |
| <em>event context</em> |
| inside the URL. The account's id will |
| be part of the URL and will be accessible when the event request is later triggered. |
| </p> |
| |
| |
| </subsection> |
| |
| <subsection name="ViewAccount.java"> |
| <source><![CDATA[ |
| 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; |
| } |
| } |
| ]]></source> |
| |
| <p> |
| 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. |
| </p> |
| |
| <p> |
| Notice how the context (from when the link was rendered) now becomes parameters |
| to the event handler method. |
| </p> |
| |
| <p> |
| 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. |
| </p> |
| |
| |
| </subsection> |
| |
| </section> |
| |
| <section name="Notes"> |
| |
| <p> |
| 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: |
| </p> |
| <p>You can do this in a template using the following syntax:</p> |
| <source><![CDATA[ |
| <t:actionlink t:id="delete" context="[account.companyId, account.id]">delete ${company.name} / ${account.id}</t:actionlink> |
| |
| ]]> </source> |
| |
| <source><![CDATA[ |
| Object onActionFromDelete(long companyId, long accountId) |
| { |
| accountDAO.delete(companyId, accountId); |
| |
| accountsSummaryPage.setMessage(String.format("Account #%d has been deleted.", accountId)); |
| |
| return accountsSummaryPage; |
| }]]></source> |
| |
| <p> |
| Alternatively, you can provide a getter which returns an object array. |
| </p> |
| <source><![CDATA[ |
| public Object[] getAccountContext() |
| { |
| return new Object[] { account.companyId, account.id }; |
| }]]></source> |
| |
| <p> |
| In the template, this would be referenced as: |
| </p> |
| <source><![CDATA[ |
| <p> |
| [<t:actionlink t:id="delete" context="accountContext">delete</t:actionlink> |
| </p>]]></source> |
| |
| <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. |
| </p> |
| </section> |
| |
| </body> |
| </document> |
