Samir Caus's Public Library

I store my object in memcache using the session.getId() identifier

of my JVM :

import javax.cache.Cache;

import javax.cache.CacheException;

import javax.cache.CacheFactory;

import javax.cache.CacheManager;

…

class MyController {

def find = {

def session = request.getSession(true)

def cache = CacheManager.getInstance().getCacheFactory().createCache

(Collections.emptyMap())

def map = new HashMap()

for (Place place : places.getPlacesList()) {

     for (int i = 0; i < place.mapUrls.length; i++ ) {

              map.put('cachedMapUrl'+i, place.mapUrls[i]) ;

     }

cache.put("mapUrls", baos.toByteArray())

CacheManager.getInstance().registerCache("_ahs" + session.getId(),

cache)

[places : places, jsessionId : session.getId()]

def changeZoom = {

def cache = CacheManager.getInstance().getCache("_ahs" + params

['jsessionId'])

def buf = (byte[]) cache.get("mapUrls")

ByteArrayInputStream bais = new ByteArrayInputStream(buf);

ObjectInputStream ois = new ObjectInputStream(bais);

def  map = (HashMap) ois.readObject()

def mapUrl = map.get('cachedMapUrl'+zoomIndex)

For a key for an entity with an entity group parent, you can use the KeyFactory.Builder class:

import com.google.appengine.api.datastore.Key;
import com.google.appengine.api.datastore.KeyFactory;

// ...
        Key k = new KeyFactory.Builder(Employee.class.getSimpleName(), 52234).addChild(ExpenseReport.class.getSimpleName(), "A23Z79").getKey();

The Builder instance's addChild() method returns the Builder, so you can chain calls to add each element of the key path. To get the complete Key value for a given builder, you call the Builder's getKey() method.