Hi,

Why would anyone use a Set for mapping a collection of an entity if Set is not going to be supported by the JSF h:dataTable?

Somebody said:



Are we now supposed to adjust the back-end to compensate for the front end?

References:
http://forums.sun.com/thread.jspa?threadID=5273924
http://www.icefaces.org/JForum/posts/list/4005.page

Any opinions and suggestions are welcome.

Thanks!

I can't speak on why jsf uses a list, but that seems perfectly acceptable. JSF is a different library from hibernate so there really is not a correlation between the 2.


I use sets whenever appropriate. If I want unique values only for instance. It also has a small footprint then a list. As in any language you shouldn't be using something just because it's easy to use, but because it fits the situation that it's in.

Why not use a Set?

I use bag (list) on one to many if there is no natural business key, and the business can't define uniqueness. For instance if theres a unique constraint in the database over a set of columns, then a set mapping can make sense...

Nice thing about bag/list is you can cheat a bit on your equals/hashcode implementations...

J

hello all, i just use a list, when i want to add additional indexing to the collection and of course when it makes sense duplicate entries. I use bags when i have some legacy or simply because when i don't want to add an additional indexing column on the db. I've use the sets less frequent that the other two but it also have it's use...

regards,


ps, don't confuse JSF with Hibernate they are not the same and they are made to accomplish two different things. If u are having troubles using sets that are defined in the pojos try to pass the whole set collection to a new arraylist, after that JSF will wrap the instance of that arraylist into a datamodel

Actually I use a set, because I think it's the appropriate semantic to use in my situation (duplicates shouldn't be allowed), but what can I do if the front-end don't have any use for a Set? So what I did is I converted all my collection mappings to a list.

I just wonder about those who use Set, how do they display it on a JSF dataTable with minimal effort. Some have made a facelets tag function that converts Set to a List, but I wonder what could be the impact on it on the model if say, the dataTable displays editable rows (each row has an h:inputText), would the values entered be propagated back to each items if in case a user modified something on the table?