I have done similar things in the past using a flat database structure to
build a nested structure.
public class Node {
private Integer nodeId; // stored in database
private String description; // stored in database
private Integer parentId; // stored in database
private List<Node> childNodes = new ArrayList<Node>(); // calculated
using parentId
}
public class NodeService {
private List<Node> getAllNodesUnjoined() {
// get all records from the flat database table
}
// use the flat structure to build a nested structure
public Node getTree() {
List<Node> nodes = getAllNodesUnjoined();
Map<Integer, Node> nodesById = new HashMap();
Node rootNode = null;
for (Node node : nodes) {
if (node.getParentId() == null) {
if (rootNode != null) {
throw new RuntimeException("More than one root node found");
}
rootNode = node;
}
nodesById.put(node.getNodeId(), node);
}
if (rootNode == null) {
throw new RuntimeException("No root node found");
}
for (Node node : nodes) {
if (node.getParentId() != null) {
Node parent = nodesById.get(node.getParentId());
parent.getChildNodes().add(node);
}
}
return rootNode;
}
}
On Tuesday, 7 February 2012, George Christman <gchrist...@cardaddy.com>
wrote:
> Hello, I was wondering if someone could help point me in the right
direction
> regarding the db and query needed to generate a database driven tree grid.
>
> This is some code I found between Tapestry-Jquery and JumpStart. I'm not
> sure what the best approach would be to generate this recursive query.
>
> Thanks in advance.
>
> static {
> ROOT.addChild(
> new TreeExample("Renault").addChild(
> new TreeExample("Mégane")).addChild(
> new TreeExample("Clio")
> .addChildrenNamed("Clio Campus", "Clio Sport")))
> .addChild(new
> TreeExample("Ferarri").addChildrenNamed("F430", "California"));
>
>
> TreeExample numbers = new TreeExample("Numbers");
> for (int i = 0; i < 10000; i++) {
> numbers.addChild(new
TreeExample(Integer.toString(i)));
> }
> ROOT.addChild(numbers);
> }
>
> --
> View this message in context:
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>
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