On Saturday, April 30, 2011 9:06:45 PM UTC-4, RH wrote:
>
> I'm looking for a simple way to persist a set of dynamic Composite
> Design Pattern objects (as described in Design Patterns by Gamma,
> Helm, Johnson, and Vlissides) with either Google's native datastore,
> JDO, or JPA, as well as send
In a nutshell, I'm trying to:
a) persist a tree structure set of objects
b) be able to recall any node and all it's children in the tree
c) be able to add a child to any node on the tree
in the GAE datastore.
On May 2, 11:24 am, supercobra wrote:
> What are you trying to achieve?
>
> -- superco
here would be an example using the heap:
class Directory {
public String name;
public ArrayList children = new ArrayList();
// could have any other properties or attributes here as well
Directory(String n){
name = n;
public void Display() {
h, I think you're right.
Any ideas on how to optimize the datastore query for a sub branch of
the tree?
With this approach I either need to
a) bring in all items in the app (possibly filtered by owner) across
the RPC boundary and then structure them in the GWT client
b) continue to look for
I will advise you to use unowned relation in this scnerio. Instead of
Directory entity having childrens...i will put parent information in the
Directory entity.. this way you can make sure one Directiry can have
millions of Child directory...as you will not max out the maximum entity
size.
class D
What do u want to optimize in Query...
It will be a simple query...
first time when you load you run query like select * from table where
parentid==null/0/or even remove where clause
then when user click on any node on UI tree then u make RPC call to bring
its child.. and load them to tree
Good point. One way I do it is walk down the tree with individual rpc calls
like Ravi said. I try not to take to much data unless its need through rpc.
Brandon
http://gwt-examples.googlecode.com
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