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https://issues.apache.org/jira/browse/ISIS-898?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16430740#comment-16430740
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Andi Huber commented on ISIS-898:
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I'm now in the need of rendering tree data for one of my projects. Good thing
is, it's not urgent, so I have time to do it right.
First of all we'd need a good general purpose API for tree-data structures that
could be added to applib. Similar to Java's Collection interface, which - as
already supported by Isis - is a good interface for list/set data-structures,
we need an equivalent for trees.
We could invent an interface 'TreeModel' such that Isis will render these
utilizing Apache Wicket's Tree Widgets. [1]
To simplify matters, we could treat this 'TreeModel' as a 'lazy view-model',
and refrain from providing any persistence mechanics for it. And by lazy I
mean, that by default only the root of the tree is rendered (with every child
collapsed, unless programmatically intended otherwise) and hence only a single
node needs to be fetched for rendering by the client by default initially. Any
expanding of tree-nodes will trigger a new Ajax request, to fetch only those
tree-nodes that are actually visible.
Data-Access API:
- depth-first/breadth first tree-node iteration/streaming of tree-nodes
- hierarchy-up tree-node iteration/streaming of tree-nodes (walking the parent
chain of a tree-node)
In addition to that the visual appearance needs some basic API as well, such as:
- expand/collapse a tree-node (programmatically)
- decorate a tree/node (e.g. to put an overlay on a tree-node's icon)
- showing/hiding tree-nodes (are rendered or not)
- enabling/disabling tree-nodes (are expandable or not)
Clearly this is just a brainstorming, we should investigate other frameworks
and collect some good ideas.
*Comments are highly appreciated!*
[1]
[http://examples7x.wicket.apache.org/tree/wicket/bookmarkable/org.apache.wicket.examples.tree.NestedTreePage?0]
> Add a table tree view to the Wicket viewer.
> -------------------------------------------
>
> Key: ISIS-898
> URL: https://issues.apache.org/jira/browse/ISIS-898
> Project: Isis
> Issue Type: New Feature
> Components: Core: Viewer: Wicket
> Affects Versions: viewer-wicket-1.6.0
> Reporter: Dan Haywood
> Priority: Minor
> Fix For: 3.0.0
>
>
> see mailing list discussion [1]
> [1] http://markmail.org/message/vu3jqmlawrskplic
> ~~~
> some further thoughts:
> For example, in Estatio there are several hierarchies
> EstatioInstance ("global") /
> EstatioInstance ("italy") /
> EstatioInstance ("Roma shopping mall")
> or:
> Property/
> Floor/
> Unit
> We'd like to render these objects in a single tree/table collection.
> ~~~
> We should distinguish two cases:
> - where all the rows are of the same type (EstatioInstance, turtles all the
> way down).
> - where all the rows are of different types (Property/Floor/Unit)
> For the former, the columns to use are exactly those of the (single) class.
> For the latter, things are more complicated, as all the objects are of
> different class. It's not clear to me what (apart from an icon and a title)
> should be shown as columns. Perhaps just the intersection of those
> properties that are common across all types (eg name?) . Or perhaps there's
> metadata (in @PropertyLayout(...)) to specify that a particular property
> should always be shown in such tree/table collections, even if it is null for
> other rows for instances of some other class.
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