I have what i believe is a simple question for those who are familiar with JSF.
I am not too familiar so before digging any further in the documentation i thought i'd ask here for advice.
My problem is quite simple: I want to display in a table the result of a JPQL query.
That query looks like this :
select a.name, b.title, b.age from table1 a, table2 b where a.id = b.id
So it returns a "list of lists" that looks like this:
((name1, title1, age1), (name2, title2, age2), ..., (nameN, titleN, ageN),
If i store the result of that query in an ArrayList (myList) in my Managed Bean, I can then do this in my XHTML page:
That of course does not work.
First because it displays the listing in one column only whereas there are 3 elements in each list. Secondly because item points to the list object, not an element of the list.
The JSF tag "language" is primarily about presentation. The number one problem here is that you have a variable presentation, so it's reasonable for JSF to expect that you'll be tweaking style info and related items to allow for that. There are a lot of options there, so they didn't try to cover them all.
The typical way to handle a situation like this is to dynamically build the columns. You do this by using a control binding reference (not a data reference) and coding a method in the backing bean to construct and lay out the columns.
Any given datatable must have a fixed number of columns, so if you want to display multiple sets of data with varying numbers of columns, each dataset would require its own datatable. If the number of sets of data is also variable, then you have to build that via control binding as well, making the datatables children of the parent container to which they are bound as well as dynamically binding columns to each datatable.
Although you think this is simple, it strikes me as classic "All You Have To Do Is" syndrome. While it's certainly not rocket science, there's more work involved than it would seem based on the basic requirements.
An IDE is no substitute for an Intelligent Developer.