DirectLink

DirectLink

net.sf.tapestry.link.DirectLink

Description
Creates a <a> hyperlink that notifies the component when the link is triggered. The link includes some context-specific data that is made available to the component's listener. This is used in cases where the ActionLink component can't be used (or is too inefficient).

See the Developers Guide ActionLink and DirectLink listeners for a more complete description.

Prior to release 2.2, this component was named Direct.

See Also
ActionLink, ExternalLink, GenericLink, PageLink, ServiceLink

Parameters

Name	Type	Direction	Required	Default	Description
listener	`IActionListener`	in	yes		Specifies an object that is notified when the link is clicked, which is typically a listener method of its container (for example, `listeners.method`).
parameters	Object or Object[] or `List`	in	no		An array of objects to be encoded into the URL. These parameters will be decoded when the link is triggered. In a web application built onto of Enterprise JavaBeans, the context is often the primary key of some Entity bean; typically such keys are Strings or Integers. A listener method can retrieve the parameters using `IRequestCycle.getServiceParameters()`. Prior to release 2.2, the parameters were always type String. They may now be of any type; type will be maintained when the parameters are later retrieved by a listener. See `DataSqueezer` for more details.
disabled	boolean	in	no	false	Controls whether the link is produced. If disabled, the portion of the template the link surrounds is still rendered, but not the link itself.
stateful	boolean	in	no	true	If true (the default), then the component requires an active (i.e., non-new) `HttpSession` when triggered. Failing that, it throws a `StaleLinkException`. If false, then no check is necessary. The latter works well with links that encode all necessary state inside the URL itself.
scheme	String	in	no		If specified, then a longer URL (including scheme, server and possibly port) is generated using the specified scheme. Server is determined fromt he incoming request, and port is deterimined from the port paramter or the incoming request.
port	int	in	no		If specified, then a longer URL (including scheme, server and port) is generated using the specified port. The server is determined from the incoming request, the scheme from the scheme parameter or the incoming request.
anchor	String	in	no		The name of an anchor or element to link to. The final URL will have '#' and the anchor appended to it.

Body: rendered
Informal parameters: allowed
Reserved parameters: "href"

Examples

In this example the DirectLink component enables users to select or delete Customers from a Customer List table.

ID Name Level

10276 Ms Sophie L. Jamies Platinum

10539 Mr Albert H. Davies Gold

10552 Mrs Jan S. Flawson Gold

10863 Mr Robert J. Hassel Silver

<table cellspacing="6">
  <tr>
   <td>ID</td>
   <td>&nbsp;</td>
   <td>Name</td>
   <td>&nbsp;</td>
   <td>Level</td>
   <td>&nbsp;</td>
  </tr>
  <tr>
   <td colspan="6"><hr></td>
  </tr>
 <span jwcid="foreachCustomer">
  <tr>
   <td><span jwcid="insertId"/></td>
   <td>&nbsp;</td>
   <td><a jwcid="customerSelectLink"> <span jwcid="insertFullName"/> </a></td>
   <td>&nbsp;</td>
   <td><span jwcid="insertMemberLevel"/></td>
   <td>
    <a jwcid="customerDeleteLink" onclick="return window.confirm('Are you sure you want remove this customer?');"> 
     <img jwcid="deleteImage" alt="Delete"/> 
    </a>
   </td>
  </tr>
 </span>
</table>


<component id="foreachCustomer" type="Foreach">
    <binding name="source" expression="visit.customerList"/>
    <binding name="value" expression="customer"/>
</component>

<component id="customerSelectLink" type="DirectLink">
    <binding name="listener" expression="listeners.customerSelectAction"/>
    <binding name="parameters" expression="customer.id"/>
</component>

<component id="customerDeleteLink" type="DirectLink">
    <binding name="listener" expression="listeners.customerDeleteAction"/>
    <binding name="parameters" expression="customer.id"/>
</component>

<component id="insertId" type="Insert">
    <binding name="value" expression="customer.id"/>
</component>

<component id="insertFullName" type="Insert">
    <binding name="value" expression="customer.fullName"/>
</component>

<component id="insertMemberLevel" type="Insert">
    <binding name="value" expression="customer.memberLevel"/>
</component>

<component id="imageDelete" type="Image"/>
    <binding name="image" expression="assets.deleteImage"//>
</component/>

<private-asset name="deleteImage" resource-path="/com/mycorp/delete.gif"/>


package com.mycorp; 

public class SalesPage extends BasePage {
    private Customer customer;
	 
    public Customer getCustomer() { return customer; }

    public void setCustomer(Customer value) {
        customer = value;
    }
    
    public void customerSelectAction(IRequestCycle cycle) {
        Visit visit = (Visit) getVisit();        
        Object[] parameters = cycle.getServiceParameters();
        Customer customer = visit.findCustomerByPrimaryKey((Integer) parameters[0]);
        // Perform some action with the selected customer.
        ..
    }

    public void customerDeleteAction(IRequestCycle cycle) {
        Visit visit = (Visit) getVisit();        
        Object[] parameters = cycle.getServiceParameters();
        Customer customer = visit.findCustomerByPrimaryKey((Integer) parameters[0]);
        visit.deleteCustomer(customer);
    }

    public void detach() {
        customer = null;
        super.detach();
    }
}

public class Visit() implements Serializable {

    public List getCustomerList() {
        List customerList = new ArrayList();         
        // Perform a database query retrieving the list of customers.
        ..        
        return customerList; 
    }
    
    public Customer findCustomerByPrimaryKey(Integer id) {
        Customer customer = null;         
        // Retrieve the customer from the database with given the customer ID.
        ..
        return customer; 
    }
    
    public void deleteCustomer(Customer customer) {
        // Delete customer from the database.
        ..       
    }        	 
}

public class Customer {
    private Integer id;
    private String fullName;
    private String memberLevel;

    public Customer(Integer id, String fullName, String memberLevel) { 
        this.id = id;
        this.fullName = fullName;
        this.memberLevel = memberLevel; 
    }

    public Integer getId() { return id; }
		
    public String getFullName() { return fullName; }

    public String getMemberLevel() { return memberLevel; }
}