[flexcoders] Error when i try to get information from a dataservice to populate my datagrid

Tue, 14 Mar 2006 01:11:54 -0800

Hi, i'm trying to create a dataservice to conect a database with my datagrid, but i get this error


Error: Item requested at index 0 was null and should not have been. Error for service 'usuario'
at mx.data::DataList/http://www.macromedia.com/2005/flex/mx/internal::requestItemAt()
at mx.data::DataList/getItemAt()
at mx.collections::ListCollectionView/getItemAt()
at mx.collections::ListCollectionViewCursor/seek()
at mx.controls.listclasses::ListBase/modelChanged()
at mx.controls::DataGrid/modelChanged()
at flash.events::EventDispatcher/dispatchEvent()
at mx.collections::ListCollectionView/dispatchEvent()
at mx.collections::ListCollectionView/http://www.macromedia.com/2005/flex/mx/internal::reset()
at mx.collections::ListCollectionView/mx.collections:ListCollectionView::listChangeHandler()
at flash.events::EventDispatcher/dispatchEvent()
at mx.data::DataList/http://www.macromedia.com/2005/flex/mx/internal::processSequenceResult()
at C:\dev\enterprise_beta1\frameworks\mx\data\errors\DataServiceError.as$34::DataListRequestResponder/result()
at mx.rpc::AsyncRequest/acknowledge()
at C:\dev\enterprise_beta1\frameworks\libs\framework.swc(mx/core/mx_internal)$35::NetConnectionMessageResponder/result()



I'm using:
  • Windows XP servicepack 2
  • Mozilla Firefox 1.5 (i've also tryed ie, but i get the same error)
  • Flex 2.0 beta 1
  • Flex Enterprise Services 2.0 beta 1
  • Flash Player 8.5 Alpha 3 (build 211)




ListaUsuarios.mxml

import mx.collections.ArrayCollection;
 import mx.data.DataService;

public var ds:DataService;

[Bindable]
public var usuarios:ArrayCollection;

public function initApp()
{
    usuarios = new ArrayCollection();
    ds = new DataService("usuario");
    ds.fill(usuarios);
}



flex-data-service.xml

<service>
<adapters>
<adapter-definition id="actionscript"   class="flex.data.adapters.ASObjectAdapter" default="true"/>
<adapter-definition id="java-dao" class="flex.data.adapters.JavaAdapter"/>
</adapters>

<default-channels>
<channel ref="my-rtmp"/>
</default-channels>

<destination id="usuario">

    <adapter ref="java-dao" />

<properties>
<metadata>
<identity property="idusuario"/>
</metadata>

<network>
<session-timeout>0</session-timeout>
<paging enabled="false" />
<throttle-inbound policy="ERROR" max-frequency="500"/>
<throttle-outbound policy="REPLACE" max-frequency="500"/>
</network>

<server>
<assembler>
<class>usuarios.UsuarioAssembler</class>
<singleton>true</singleton>
</assembler>

<fill-method>
<name>loadUsuarios</name>
</fill-method>

</server>
</properties>
</destination>

</service>



UsuarioAssembler.java

package usuarios;

import java.util.List;

public class UsuarioAssembler
{

public List loadUsuarios()
{
UsuarioDAO dao = new UsuarioDAO();
return dao.getUsuarios();
}

}



UsuarioDAO.java

package usuarios;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

public class UsuarioDAO
{
public List getUsuarios() throws DAOException
{
ArrayList list = new ArrayList();
Connection c = null;
try
{
c = ConexionBD.getConexion();
Statement s = c.createStatement();
ResultSet rs = s.executeQuery("SELECT * FROM alumnos ORDER BY nombre");
Usuario usuario;
while (rs.next())
{
usuario = new Usuario();
usuario.setIdUsuario(rs.getString("id_usuario"));
usuario.setPassword(rs.getString("password"));
usuario.setNombre(rs.getString("nombre"));
list.add(usuario);
}
}
catch (SQLException e)
{
e.printStackTrace();
throw new DAOException(e);
}
finally
{
ConexionBD.cerrarConexion(c);
}
return list;
}
}




Everything in java works correctly, but when i try to call it from flex doesn't work.

If anybody can help me, i will be very pleased.
Thanks in advance.


--
Manuel Bordallo
[EMAIL PROTECTED]

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