How to download huge numbers of child objects as CSV in Silverstripe CMS?

Question

I'm working on a Silverstripe project which has a Batch > Item relationship.

A Batch can have up to 50,000 Items.

This is how the relationship is set-out:

class Item extends DataObject {

  private static $has_one = array(
      'Batch' => 'Batch'
  );

class Batch extends DataObject {

  private static $has_many = array(
      'Items' => 'Item'
  );

class BatchAdmin extends ModelAdmin {

  private static $managed_models = array(
      'Batch',
      'Item'
  );

This natively gives the CMS user the ability to download all Items as a CSV from the CMS.

I'm trying to work out two things:

1. How do I make sure that large downloads don't fail due to lack of memory/ script time etc?

2. How do I add an "Export to CSV" button to each Batch which downloads only the Items in that batch as a CSV?

Answer 1

To add an Export to CSV button to Batch which exports the related Items we add a GridFieldExportButton to the Batch CMSFields:

class Batch extends DataObject {

    private static $has_many = array(
        'Items' => 'Item'
    );

    public function getCMSFields() {
        $itemsConfig = GridFieldConfig_RelationEditor::create();
        $itemsConfig->addComponent(new GridFieldExportButton());

        $itemsField = new GridField(
            'Items',
            'Items',
            $this->Items(),
            $itemsConfig
        ); 

        $fields = new FieldList(
            $itemsField
        );

        return $fields;
    }

}