java - How to insert a value into Set collection in Struts 2

Question

I am doing a project using Struts2 and I have a problem assigning a set collection.

Here's my Action (I eliminated the irrelevant part)

public class TeamAction extends BaseAction implements ModelDriven<Team>
{
 Team team=new Team();

}

Here's my model Team (I eliminated the irrelevant part)

private TeamId id;
private Set students = new HashSet(0);

Here's my JSP part

<input type="text" name=team.student[0].id />

Now the problem is I can't insert the right value into this Set collection in by ModelDriven, it will throw a exception. Could you please tell me what to write in JSP file, so I can insert a value to Set collection in my model?

Answer 1

Set is a Collection and as any other collection could be indexed by a property.

@Element(value = Student.class)
@Key(value = Integer.class)
@KeyProperty(value = "id") 
@CreateIfNull(value = true)
private Set<Student> students = new HashSet(0);
//getter and setter, also for Student class that should have Integer id.

in JSP

<s:iterator value="students " var="student">
  <s:textfield name="students(%{#student.id}).name" />
</s:iterator>

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More about this see

Indexing a collection by a property of that collection.

It is also possible to obtain a unique element of a collection by passing the value of a given property of that element. By default, the property of the element of the collection is determined in <Class>->conversion.properties using KeyProperty_xxx=yyy, where xxx is the property of the bean Class that returns the collection and yyy is the property of the collection element that we want to index on.