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Re: TransformedList question

by James Lemieux :: Rate this Message:

Holger has it exactly right. CollectionList is the de facto list to use when a single source element produces multiple transformed elements. Using CollectionList is the first half of the solution.

The second half is the TextFilterator which extracts Strings from the Issues to be considered when filtering any given Issue. That TextFilterator needs to return all users as Strings in addition to any other Strings you deem worthy of consideration when filtering your Issues. Again, Holger has sketched the code well.

I'd urge you to check out our screencasts here:

http://www.publicobject.com/glazedlistsdeveloper/

as they do a good job of introducing each concept separate and apart from each other. The screencast of FilterList may be particularly useful to you.

James

On 8/15/06, wsnyder6 <wsnyder6@...> wrote:

Awesome. I will try this.

I also thought that I could use the TransformedList like such:

class ItemsToLabelsList extends TransformedList {

        public IssuesToUsersList(EventList source) {
            super(source);
            for (Object elem : source) {
                addAll( ((Issue)elem).getUsers() );
            }
            source.addListEventListener(this);
        }

        public void listChanged(ListEvent listChanges) {
            updates.forwardEvent(listChanges);
        }

    }

Holger Brands-2 wrote:

>
> Hi,
>
>>
>> What if each Issue could have more than one User attached to it? How then
>> would I implement the TransformedList with Dynamic filtering?
>>
>
> The tutorial shows filtering of issues by the issue reporter:
> Issue.getReporter()
> For the following discussion let's assume you want to filter by
> all users of the issue as defined by method Issue.getAllUsers().
>
> You would have to change
> a) the IssueToUserList from tutorial chapter 4
> b) the IssuesForUsersMatcher from tutorial chapter 5.
>
> a) Instead of using the IssueToUserList I would use a CollectionList like
> this:
>
> CollectionList<Issue, String> usersNonUnique = new CollectionList<Issue,
> String>(source, new IssueToUsersModel());
>
>
> /**
>  * Determines all users for an issue.
>  */
> public class IssueToUsersModel implements CollectionList.Model<Issue,
> String> {
>     public List<String> getChildren(Issue issue) {
>         return issue.getAllUsers();
>     }
> }
>
> The CollectionList is a TransformedList that maps each issue from the
> source list to the associated users.
> It's a kind of parent-child relationship.
>
>
> b) IssuesForUsersMatcher should be changed to match all issue users using.
> Issue.getAllUsers():
>
>    /**
>     * Test whether to include or not include the specified issue based
>     * on whether or not their user is selected.
>     */
>    public boolean matches(Object o) {
>        if(o == null) return false;
>        if(users.isEmpty()) return true;
>
>        Issue issue = (Issue)o;
>        for (Iterator i = issue.getAllUsers().iterator(); i.hasNext(); ) {
>          if(users.contains(i.next())) return true;
>        }
>        return false;
>     }
>
>
> Hope this helps,

> Holger
>
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