package org.jboss.errai.jpa.client.local;
import org.jboss.errai.common.client.api.Assert;
import com.google.gwt.json.client.JSONException;
import com.google.gwt.json.client.JSONObject;
import com.google.gwt.json.client.JSONParser;
import com.google.gwt.json.client.JSONString;
import com.google.gwt.json.client.JSONValue;
/**
* Holder class for a storage key: a tuple of type and identity value.
* <p>
* Instances of this class are immutable.
*
* @param <X> The entity's Java type
* @param <T> The entity's identity type
* @author Jonathan Fuerth <jfuerth@gmail.com>
*/
public class Key<X, T> {
private final ErraiManagedType<X> entityType;
private final T id;
/**
* Creates a key that uniquely identifies an entity of a particular type (the
* entity with this identity does not necessarily exist, but if it did, this
* would be its identity).
*
* @param entityType The type of the entity. Must not be null.
* @param id The ID of the entity. Must not be null.
* @throws NullPointerException if either argument is null.
*/
public Key(ErraiManagedType<X> entityType, T id) {
this.entityType = Assert.notNull(entityType);
this.id = Assert.notNull(id);
}
/**
* Returns a Key instance for the entity type of the given class.
*
* @param em
* The entity manager (required for looking up the EntityType for the
* given class). Must not be null.
* @param entityClass
* The class of the entity for the key. Must not be null.
* @param id
* The ID value for the entity. Must not be null.
* @return A Key instance for the given entity type and ID value.
* @throws NullPointerException
* if any argument is null.
* @throws IllegalArgumentException
* if {@code entityClass} is not a known JPA entity type.
*/
public static <X, T> Key<X, T> get(ErraiEntityManager em, Class<X> entityClass, T id) {
ErraiIdentifiableType<X> entityType = em.getMetamodel().entity(entityClass);
return new Key<X, T>(entityType, id);
}
/**
* Returns the managed type this key refers to.
*
* @return the entity type of the key. Never null.
*/
public ErraiManagedType<X> getEntityType() {
return entityType;
}
/**
* Returns the ID value for this key.
*
* @return the ID value of the key. Never null.
*/
public T getId() {
return id;
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result
+ ((entityType == null) ? 0 : entityType.hashCode());
result = prime * result + ((id == null) ? 0 : id.hashCode());
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
Key<?, ?> other = (Key<?, ?>) obj;
if (entityType == null) {
if (other.entityType != null)
return false;
}
else if (!entityType.equals(other.entityType))
return false;
if (id == null) {
if (other.id != null)
return false;
}
else if (!id.equals(other.id))
return false;
return true;
}
@Override
public String toString() {
return "Key [entityType=" + entityType + ", id=" + id + "]";
}
/**
* Returns a JSON string representation of this key which can be turned back
* into a Key instance via
* {@link Key#fromJson(ErraiEntityManager, String, boolean)}.
*
* @see #toJsonObject()
* @return a JSON-formatted string. Never null.
*/
public String toJson() {
return toJsonObject().toString();
}
/**
* Returns a JSONObject representation of this key which can be turned back
* into a Key instance via
* {@link Key#fromJsonObject(ErraiEntityManager, JSONObject, boolean)}.
*
* @see #toJson()
* @return a JSON object that represents this key. Never null.
*/
public JSONObject toJsonObject() {
JSONObject keyJson = new JSONObject();
keyJson.put("entityType", new JSONString(entityType.getJavaType().getName()));
keyJson.put("id", JsonUtil.basicValueToJson(id));
return keyJson;
}
/**
* Returns a Key instance based on the given JSON string.
*
* @param em
* The entity manager that can be used to look up the entity type
* corresponding with the key.
* @param key
* The key to parse.
* @param failIfNotFound
* If true, and the entity type given in {@code key} is not known to
* {@code em}, an IllegalArgumentException will be thrown.
* @return An instance of Key that corresponds with the entity type and ID of
* the given JSON string.
*/
public static Key<?, ?> fromJson(ErraiEntityManager em, String key, boolean failIfNotFound) {
JSONValue k;
try {
k = JSONParser.parseStrict(key);
} catch (JSONException e) {
throw new JSONException("Input: " + key, e);
}
return fromJsonObject(em, k.isObject(), failIfNotFound);
}
/**
* Returns a Key instance based on the given JSON object.
*
* @param em
* The entity manager that can be used to look up the entity type
* corresponding with the key.
* @param key
* The properties of the key to create.
* @param failIfNotFound
* If true, and the entity type given in {@code key} is not known to
* {@code em}, an IllegalArgumentException will be thrown.
* @return An instance of Key that corresponds with the entity type and ID of
* the given JSON object.
*/
public static Key<?, ?> fromJsonObject(ErraiEntityManager em, JSONObject key, boolean failIfNotFound) {
String entityClassName = key.get("entityType").isString().stringValue();
ErraiIdentifiableType<Object> et = em.getMetamodel().entity(entityClassName, failIfNotFound);
if (et == null) {
return null;
}
ErraiSingularAttribute<?, Object> idAttr = et.getId(Object.class);
Object id = JsonUtil.basicValueFromJson(key.get("id"), idAttr.getJavaType());
return new Key<Object, Object>(et, id);
}
}