documentation/sqlcontainer/sqlcontainer-nonimplemented.asciidoc


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---
title: Non-Implemented Methods
order: 8
layout: page
---

[[sqlcontainer.nonimplemented]]
= Non-Implemented Methods

Due to the database connection inherent to the SQLContainer, some of the methods
from the container interfaces of Vaadin can not (or would not make sense to) be
implemented. These methods are listed below, and they will throw an
[classname]#UnsupportedOperationException# on invocation.


----
public boolean addContainerProperty(Object propertyId,
                                    Class<?> type,
                                    Object defaultValue)
public boolean removeContainerProperty(Object propertyId)
public Item addItem(Object itemId)
public Object addItemAt(int index)
public Item addItemAt(int index, Object newItemId)
public Object addItemAfter(Object previousItemId)
public Item addItemAfter(Object previousItemId, Object newItemId)
----

Additionally, the following methods of the [classname]#Item# interface are not
supported in the [classname]#RowItem# class:


----
public boolean addItemProperty(Object id, Property property)
public boolean removeItemProperty(Object id)
----

[[sqlcontainer.nonimplemented.getitemids]]
== About the getItemIds() method

To properly implement the Vaadin [classname]#Container# interface, a
[methodname]#getItemIds()# method has been implented in the
[classname]#SQLContainer#. By definition, this method returns a collection of
all the item IDs present in the container. What this means in the
[classname]#SQLContainer# case is that the container has to query the database
for the primary key columns of all the rows present in the connected database
table.

It is obvious that this could potentially lead to fetching tens or even hundreds
of thousands of rows in an effort to satisfy the method caller. This will
effectively kill the lazy loading properties of [classname]#SQLContainer# and
therefore the following warning is expressed here:


[WARNING]
====
It is highly recommended not to call the [methodname]#getitemIds()# method,
unless it is known that in the use case in question the item ID set will always
be of reasonable size.

====