I am trying to find an example of how to populate a select list of objects,
show the correct item as selected, and if the selection is saved, properly
update the object containing the item. In the example below, I would want to
show a group of fields for Student information with a select list of
Campuses. If the Student is already stored with a specific Campus, that
should be selected. If the selection choice is changed, saving the Student
should update what Campus object is contained by the Student.
I have a custom TypeConverter to convert between the Campus id string and
Campus objects and I can see the conversion code executes fine.
Unfortunately, saving a selection results in an "invalid field value for
field 'campus'" error and when I first call up the page, the selected Campus
is not the correct one.
public class Student {
private Campus campus;
public Campus getCampus() {return campus; }
public void setCampus(Campus campus) {this.campus = campus; }
}
public class Campus {
private Long id;
private String name;
public Long getId() {return name; }
public void setId(Long id) {this.id = id; )
public String getName() {return name; }
public void setName(String name) {this.name = name; }
}
public class StudentAction extends ActionSupport implements ModelDriven,
Preparable {
protected Object model;
private Student student;
private Campus campus;
private List<Campus> campusList;
private DB db;
private long id;
public void prepare() throws Exception {
campusList = db.findAllCampuses();
if (getId() == 0) {
student = db.createNewStudent();
} else {
student = db.findByStudentId(getId());
}
}
public String save() {
try {
db.save(getModel());
} catch (Exception e) {
return ERROR;
}
return SUCCESS;
}
public Student getModel() {return student; }
public long getId() {return id; }
public void getId() {return id; }
}
public class CampusConverter extends StrutsTypeConverter {
private DB db;
public Object convertFromString(Map context, String[] values, Class
toClass) {
Campus campus = null;
if (values != null && values.length > 0 && values[0] != null &&
values[0].length() > 0) {
campus = db.findCampusById(new Long(values[0]));
}
return campus;
}
public String convertToString(Map context, Object o) {
if (o instanceof Campus) {
return ((Campus)o).getId().toString();
}
return "";
}
}
<body>
<s:form action="student_save" method="post">
<s:select name="campus" list="campusList" listValue="name"
listKey="id" label="%{getText('label.campus')}" />
<s:hidden name="id" value="%{id}" />
<s:submit value="%{getText('button.label.submit')}"/>
</s:form>
</body>
Suggestions, corrections, pointers, or links to examples/tutorials of how to
do this properly would be greatly appreciated.
Regards,
Lance Hill
