ADF Data Binding : Iteration in child records.

Question

I have the following situation and I cannot find a solution :
I have two view objects, StudentList and CourseList. I have also a View Link "StudentsInCourse", connecting "StudentList" and "CourseList" with cardinality M:N. This connection is exposed in "StudentList" with a property getCourses.
I need to build a page (JSP) to show the student list, and for each student, show the courses they attend to (separeted by comma). Something like :
Student1 Course1, Course2, Course3
Student2 Course1
Student3 Course4, Course5
My first attempt to achieve this was (tags :
c:forEach var="Row" items="${bindings.StudentList.rangeSet}
c:out value="${Row.Studentname}
c:forEach var="CourseRow" items="${Row.courses}
c:out value="${CourseRow.Coursename} ,
/c:forEach
/c:forEach
Well, it didn't work. The iteration doesn`t happen, since the expression ${Row.courses} doesn't appear to be a valid collection. What object is represented by "Row" ? Is that not my ViewRowImpl?
My second attempt was to bind the view link (StudentsInCourse) in the UI Model. So I've put an iterator for it and tried this :
c:forEach var="Row" items="${bindings.StudentList.rangeSet}
c:out value="${Row.Studentname}
c:forEach var="CourseRow" items="${bindings.StudentsInCourse.rangeSet}
c:out value="${CourseRow.Coursename} ,
/c:forEach
/c:forEach
It didn't work, it shows the same course list for all students. I guess this behaviour is expected, since the current row is not changed during iteration.
I guess the possible solution would be invoke the "getCourses" property in StudentListImpl, using EL. Although, I tried several expressions and nothing.
What would be the correct expression to achieve this?
I also read (http://radio.weblogs.com/0118231/2004/07/20.html#a354) that "Tree binding" would be the way to do that, and right now I am trying this path...
thanks,
Daniel Melo

Answer 1

Tree Binding made the task, BUT it broke my application.
I folled the instructions of "Working with Tree Controls in ADF-Enablad Web Pages" in JDev help.
Although, before Step 9, I had to select the Iterator of the master list (in my case StudentsList) in order to the Data Collection Definitions appear.
This step is not described in the document. Is that correct?
It broke my application, because in this same page I had a button to open a form to input data.
I have a binding for "Create" operation in the StudentsList iterator (the master iterator).
The input for page was being requested by a postback pattern :
html:image src="Images/ico_new.gif" property="event_Create" /
When I click this image, I have the error :
JBO-25005: Nome do objeto Courses_1641 do tipo Definicao de Binding de Iterador é inválido
(Sorry for the translated error message. By the way, how can I configure ADF to show original english messages?)
It says something like : "Name of object Courses_1641, of type Iterator binding definition is invalid."
That happens with every submit buttons and the number after courses is random, it changes every time.
Well, I changed the "New" button to a link, like :
a href="#" OnClick="javascript: document.location.href='listStudents.do?event=Create';" img src="Images/ico_new.gif" border="0" /a
And it works like this!
The problem is that I can't change all my buttons in the page to links. I need that some of them as submit buttons.
Kind of tough situation, I guess...
Thanks very much
Daniel Melo