eurecom.store.jdo

Class UtilJDO

java.lang.Object

eurecom.store.jdo.UtilJDO

public class UtilJDO
extends java.lang.Object

This is the utility class for all servlets. It provides method for inserting, deleting, searching the entity from data store. Also contains method for displaying the entity in JSON format.

Constructor Summary

Constructors

Constructor and Description
UtilJDO()

Method Summary

Methods

Modifier and Type	Method and Description
static void	deleteEntity(com.google.appengine.api.datastore.Key key) Delete the entity from persistent store represented by the key
static void	deleteEntity(java.util.List<com.google.appengine.api.datastore.Key> keys) Delete list of entities given their keys
static com.google.appengine.api.datastore.Entity	findEntity(com.google.appengine.api.datastore.Key key) Search and return the entity from datastore.
static com.google.appengine.api.datastore.DatastoreService	getDatastoreServiceInstance() get DatastoreService instance
static java.lang.String	getErrorMessage(java.lang.Exception ex) Utility method to send the error back to UI
static java.lang.Iterable<com.google.appengine.api.datastore.Entity>	listChildKeys(java.lang.String kind, com.google.appengine.api.datastore.Key ancestor)
static java.lang.Iterable<com.google.appengine.api.datastore.Entity>	listChildren(java.lang.String kind, com.google.appengine.api.datastore.Key ancestor) Search entities based on ancestor
static java.lang.Iterable<com.google.appengine.api.datastore.Entity>	listEntities(java.lang.String kind, java.lang.String searchBy, java.lang.String searchFor) Search entities based on search criteria
static void	persistEntity(com.google.appengine.api.datastore.Entity entity)
static java.lang.String	writeJSON(java.lang.Iterable<com.google.appengine.api.datastore.Entity> entities) List the entities in JSON format
static java.lang.String	writeJSON(java.lang.Iterable<com.google.appengine.api.datastore.Entity> entities, java.lang.String childKind, java.lang.String fkName) Retrieves Parent and Child entities into JSON String

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

UtilJDO

public UtilJDO()

Method Detail

persistEntity

public static void persistEntity(com.google.appengine.api.datastore.Entity entity)

Parameters:

entity - : entity to be persisted

deleteEntity

public static void deleteEntity(com.google.appengine.api.datastore.Key key)

Delete the entity from persistent store represented by the key

Parameters:

key - : key to delete the entity from the persistent store

deleteEntity

public static void deleteEntity(java.util.List<com.google.appengine.api.datastore.Key> keys)

Delete list of entities given their keys

Parameters:

keys -

findEntity

public static com.google.appengine.api.datastore.Entity findEntity(com.google.appengine.api.datastore.Key key)

Search and return the entity from datastore.

Parameters:

key - : key to find the entity

Returns:

entity

listEntities

public static java.lang.Iterable<com.google.appengine.api.datastore.Entity> listEntities(java.lang.String kind,
                                                                         java.lang.String searchBy,
                                                                         java.lang.String searchFor)

Search entities based on search criteria

Parameters:

kind -

searchBy - : Searching Criteria (Property)

searchFor - : Searching Value (Property Value)

Returns:

List all entities of a kind from the cache or datastore (if not in cache) with the specified properties

listChildren

public static java.lang.Iterable<com.google.appengine.api.datastore.Entity> listChildren(java.lang.String kind,
                                                                         com.google.appengine.api.datastore.Key ancestor)

Search entities based on ancestor

Parameters:

kind -

ancestor -

Returns:

listChildKeys

public static java.lang.Iterable<com.google.appengine.api.datastore.Entity> listChildKeys(java.lang.String kind,
                                                                          com.google.appengine.api.datastore.Key ancestor)

Parameters:

kind -

ancestor -

Returns:

writeJSON

public static java.lang.String writeJSON(java.lang.Iterable<com.google.appengine.api.datastore.Entity> entities)

List the entities in JSON format

Parameters:

entities - entities to return as JSON strings

writeJSON

public static java.lang.String writeJSON(java.lang.Iterable<com.google.appengine.api.datastore.Entity> entities,
                         java.lang.String childKind,
                         java.lang.String fkName)

Retrieves Parent and Child entities into JSON String

Parameters:

entities - : List of parent entities

childKind - : Entity type for Child

fkName - : foreign-key to the parent in the child entity

Returns:

JSON string

getErrorMessage

public static java.lang.String getErrorMessage(java.lang.Exception ex)
                                        throws java.io.IOException

Utility method to send the error back to UI

Parameters:

data -

resp -

Throws:

java.io.IOException

getDatastoreServiceInstance

public static com.google.appengine.api.datastore.DatastoreService getDatastoreServiceInstance()

get DatastoreService instance

Returns:

DatastoreService instance