package com.alexrnl.commons.database;

import java.util.Set;

/**
 * Basic CRUD operations on an abstract object.
 * @author Alex
 * @param <T>
 *        The class of the object to manipulate.
 */
public interface DAO<T extends Entity> {
	
	/**
	 * Create operation.
	 * @param obj
	 *        the object to create.
	 * @return <code>null</code> if the creation of the object has failed, the new reference to the
	 *         object if the creation succeeded.
	 */
	T create (T obj);
	
	/**
	 * Read operation.
	 * @param id
	 *        the id of the object to retrieve.
	 * @return The object which matches the <code>id</code> or <code>null</code> if no matches had
	 *         been found.
	 */
	T find (int id);
	
	/**
	 * Update operation.
	 * @param obj
	 *        the object to update.
	 * @return <code>true</code> if the update of the object has been successful.
	 */
	boolean update (T obj);
	
	/**
	 * Delete operation.
	 * @param obj
	 *        the object to delete.
	 * @return <code>true</code> if the deletion of the object has been successful.
	 */
	boolean delete (T obj);
	
	/**
	 * Retrieve all the objects available.<br />
	 * <em>Use with caution.</em>
	 * @return A collection with all the objects.
	 */
	Set<T> retrieveAll ();
	
	/**
	 * Retrieve a collection of object matching
	 * @param field
	 *        the field to search
	 * @param value
	 *        the value to test
	 * @return A collection with the object matching the
	 */
	Set<T> search (Column field, String value);
}

package com.alexrnl.commons.database;

import java.util.Set;

/**
 * Basic CRUD operations on an abstract object.
 * @author Alex
 * @param <T>
 *        The class of the object to manipulate.
 */
public interface DAO<T extends Entity> {
	
	/**
	 * Create operation.
	 * @param obj
	 *        the object to create.
	 * @return <code>null</code> if the creation of the object has failed, the new reference to the
	 *         object if the creation succeeded.
	 */
	T create (T obj);
	
	/**
	 * Read operation.
	 * @param id
	 *        the id of the object to retrieve.
	 * @return The object which matches the <code>id</code> or <code>null</code> if no matches had
	 *         been found.
	 */
	T find (int id);
	
	/**
	 * Update operation.
	 * @param obj
	 *        the object to update.
	 * @return <code>true</code> if the update of the object has been successful.
	 */
	boolean update (T obj);
	
	/**
	 * Delete operation.
	 * @param obj
	 *        the object to delete.
	 * @return <code>true</code> if the deletion of the object has been successful.
	 */
	boolean delete (T obj);
	
	/**
	 * Retrieve all the objects available.<br />
	 * <em>Use with caution, it can consume a lot of memory.</em>
	 * @return A collection with all the objects.
	 */
	Set<T> retrieveAll ();
	
	/**
	 * Retrieve a collection of object matching
	 * @param field
	 *        the field to search
	 * @param value
	 *        the value to test
	 * @return A collection with the object matching the
	 */
	Set<T> search (Column field, String value);
}

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