..	*******************************************************************************
	* MetaFactory.io R2
	* Technical Documentation
	* 
	* File name   : H2DragAndDrop.rst
	* Created by  : Ralph Oudejans
	* Last update : 02-03-2021
	* Updated by  : Niels de Nies
	*
	* MetaFactory BV Amsterdam 
	*******************************************************************************

.. include:: /inline-images.txt

Drag & Drop
===========

.. admonition:: Internal use

	|Internal M| This topic is intended for MetaFactory developers only


.. rubric:: Steps to implement the feature


Drag & Drop of an item in a list involves a dragable object (e.g. 'Subtask') and a reference to a parent object (e.g. 'Task').

In order to implement this feature take the following steps:

#. 	Add metadata to the draggable object to mark it orderable within a certain reference (e.g. reference 'task' )

	.. code-block:: xml
		:caption: model.xml
		:name: model.xml01
		:linenos:
		:emphasize-lines: 4

		<object name="Subtask">
			<metadata>
				
				<orderable>task</orderable>
			</metadata>
			
			<reference name="task" type="Task">
				
			</reference>
		</object>

	|Exclam M| In the <orderable> metadata you need to specify the `name` of a `reference`, **not** the name of an object.

#. 	Add an attribute `sortOrder` to the draggable object (here object `Subtask`)

	.. code-block:: xml
		:caption: model.xml
		:name: model.xml02
		:linenos:
		:emphasize-lines: 6,7,8,9,10,11

		<object name="Subtask">
			<metadata>
				<orderable>task</orderable>
			</metadata>
			
			<attribute name="sortOrder" type="Integer" notnull="true">
				<metadata>
					<entity.default.value>Integer.MAX_VALUE</entity.default.value>
					<list.relation.mgmt>[number]</list.relation.mgmt>
				</metadata>
			</attribute>
			<reference name="task" type="Task">
				<metadata>
					
				</metadata>
			</reference>
		</object>

#. 	Add metadata to the reference to create a finder (e.g. `findByTask`)

	.. code-block:: xml
		:caption: model.xml
		:name: model.xml03
		:linenos:
		:emphasize-lines: 16

		<object name="Subtask">
			<metadata>
				
				<orderable>task</orderable>
			</metadata>
			
			<attribute name="sortOrder" type="Integer" notnull="true">
				<metadata>
					<entity.default.value>Integer.MAX_VALUE</entity.default.value>
					<list.relation.mgmt>[number]</list.relation.mgmt>
				</metadata>
			</attribute>
			<reference name="task" type="Task">
				<metadata>
					
					<create.finder.method.list>true</create.finder.method.list>
				</metadata>
			</reference>
		</object>


#. Generate the application

#. 	Create a `changeSet` in the Liquibase alters changelog to add the column to the table of the draggable object.

	Set a default value of 0 as the sort_order is required and must not be null.
	On the entity the default value becomes Integer.MAX_VALUE, however this is not supported by SQL. 0 is fine to start with.

	.. code-block:: xml
		:caption: [projectdir]\\[backenddir]\\src\\main\\resources\\config\\liquibase\\liquibase-alters-changeLog.xml
		:name: liquibase-alters-changeLog.xml
		:linenos:
		:emphasize-lines: 3,4,5,6,7,8,9

<<<<<<< HEAD
		<databaseChangeLog >
			
=======
		<databaseChangeLog>
>>>>>>> 64e54eae0b2fb05be64238bd915b09495d6b5888
			<changeSet id="[id-named-after-jira-issue]" author="[your-initials]">
				<addColumn tableName="subtask">
					<column name="sort_order" type="INT" defaultValueNumeric="0">
						<constraints nullable="false" />
					</column>
				</addColumn>
			</changeSet>
		</databaseChangeLog>

	|Glasses M| Read more about :ref:`Liquibase change sets <Reference/TechnologyStack/Liquibase:Liquibase>`

#.  Run the application.

.. Demonstration
.. -------------

.. Demonstration of the feature can be found here.

.. .. todo::

.. 	Insert a link to the page in the Showcase application that demonstrates the Drag & Drop feature.