LightPIT: src/main/java/de/uapcore/lightpit/dao/ChildEntityDao.java@e2aa673dd473

     1 /*

     2  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.

     3  *

     4  * Copyright 2018 Mike Becker. All rights reserved.

     5  *

     6  * Redistribution and use in source and binary forms, with or without

     7  * modification, are permitted provided that the following conditions are met:

     8  *

     9  *   1. Redistributions of source code must retain the above copyright

    10  *      notice, this list of conditions and the following disclaimer.

    11  *

    12  *   2. Redistributions in binary form must reproduce the above copyright

    13  *      notice, this list of conditions and the following disclaimer in the

    14  *      documentation and/or other materials provided with the distribution.

    15  *

    16  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

    17  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

    18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

    19  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE

    20  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

    21  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

    22  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

    23  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

    24  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

    25  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

    26  * POSSIBILITY OF SUCH DAMAGE.

    27  *

    28  */

    29 package de.uapcore.lightpit.dao;

    31 import java.sql.SQLException;

    32 import java.util.List;

    34 public interface ChildEntityDao<T, P> {

    36     /**

    37      * Lists all entities being a child of the specified parent.

    38      * @param parent the parent

    39      * @return the list of child instances

    40      * @throws SQLException on any kind of SQL errors

    41      */

    42     List<T> list(P parent) throws SQLException;

    44     /**

    45      * Finds an entity by its integer ID.

    46      * It is not guaranteed that referenced entities are automatically joined.

    47      *

    48      * @param id the id

    49      * @return the enity or null if there is no such entity

    50      * @throws SQLException on any kind of SQL errors

    51      */

    52     T find(int id) throws SQLException;

    54     /**

    55      * Inserts an instance into database.

    56      * It is not guaranteed that generated fields will be updated in the instance.

    57      *

    58      * @param instance the instance to insert

    59      * @param parent a reference to the parent

    60      * @throws SQLException on any kind of SQL errors

    61      */

    62     void save(T instance, P parent) throws SQLException;

    64     /**

    65      * Updates an instance in the database.

    66      *

    67      * @param instance the instance to insert

    68      * @return true if an instance has been updated, false if no instance with the specified ID was found

    69      * @throws SQLException on any kind of SQL errors

    70      */

    71     boolean update(T instance) throws SQLException;

    73     /**

    74      * Updates an instance in the database changing the parent.

    75      * This operation is not supported by default.

    76      *

    77      * @param instance the instance to insert

    78      * @param newParent a reference to the new parent

    79      * @return true if an instance has been updated, false if no instance with the specified ID was found

    80      * @throws SQLException on any kind of SQL errors

    81      * @see #isChangingParentSupported()

    82      */

    83     default boolean update(T instance, P newParent) throws SQLException {

    84         throw new UnsupportedOperationException();

    85     }

    87     /**

    88      * Returns true if changing the parent is supported by this DAO.

    89      * This method must return true, if {@link #update(Object, Object)} is implemented.

    90      * @return true, if changing the parent is supported

    91      */

    92     default boolean isChangingParentSupported() {

    93         return false;

    94     }

    96     /**

    97      * Inserts or updates an instance in the database.

    98      * Tries an update first and if that fails, performs a save.

    99      * If changing a parent is not supported by this DAO,

   100      * specifying an alternate parent for an existing instance has no effect.

   101      *

   102      * @param instance the instance to insert or update

   103      * @param parent a reference to the parent

   104      * @throws SQLException on any kind of SQL errors

   105      * @see #update(Object)

   106      * @see #update(Object, Object)

   107      * @see #save(Object, Object)

   108      */

   109     default void saveOrUpdate(T instance, P parent) throws SQLException {

   110         if (isChangingParentSupported()) {

   111             if (!update(instance, parent)) save(instance, parent);

   112         } else {

   113             if (!update(instance)) save(instance, parent);

   114         }

   115     }

   116 }

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