I need to create a custom DataSourceIterator so that I can pass a related collection's properties to the sonata admin bundle's exportAction (I think this is the only way to achieve the export of one-to-many values, I may be wrong). I have traced backwards how my admin class is currently generating a DataSourceIterator (I think) - see below. Pres…

gistfile1.php

// vendor/sonata-project/admin-bundle/Sonata/AdminBundle/Admin/Admin.php

/**
     * @return
     */
    public function getDataSourceIterator()
    {
        $datagrid = $this->getDatagrid();
        $datagrid->buildPager();

        return $this->getModelManager()->getDataSourceIterator($datagrid, $this->getExportFields());
    }


// $this->getModelManager() is as follows:

/**
     * {@inheritdoc}
     */
    public function getModelManager()
    {
        return $this->modelManager;
    }

// and $this->modelManager is set using this method:

    /**
     * @param \Sonata\AdminBundle\Model\ModelManagerInterface $modelManager
     */
    public function setModelManager(ModelManagerInterface $modelManager)
    {
        $this->modelManager = $modelManager;
    }

// so, the getDataSourceIterator method that is called once the modelManager property is retrieved is defined in the ModelManagerInterface class and looks like this:

// vendor/sonata-project/admin-bundle/Sonata/AdminBundle/Model/ModelManagerInterface.php

   /**
     * @param DatagridInterface $datagrid
     * @param array                                          $fields
     * @param null                                           $firstResult
     * @param null                                           $maxResult
     *
     * @return \Exporter\Source\SourceIteratorInterface
     */
    function getDataSourceIterator(DatagridInterface $datagrid, array $fields, $firstResult = null, $maxResult = null);

// and is implemented, from what I can tell, in the ModelManager class like this:

// vendor/sonata-project/doctrine-orm-admin-bundle/Sonata/DoctrineORMAdminBundle/Model/ModelManager.php

    /**
     * {@inheritdoc}
     */
    public function getDataSourceIterator(DatagridInterface $datagrid, array $fields, $firstResult = null, $maxResult = null)
    {
        $datagrid->buildPager();
        $query = $datagrid->getQuery();

        $query->select('DISTINCT ' . $query->getRootAlias());
        $query->setFirstResult($firstResult);
        $query->setMaxResults($maxResult);

        return new DoctrineORMQuerySourceIterator($query instanceof ProxyQuery ? $query->getQuery() : $query, $fields);
    }

I just want to override the query in the getDataSourceIterator function or export query. I want to change entire query with multiple joins so that I can get my required field exported. Is it possible? Any help is much appreciated.