In shopware it is possible to import/export data with a profile. See the following link. https://docs.shopware.com/en/shopware-en/settings/importexport
The only problem now is that I want to upload data of a custom entity. I can't find the custom entity in the profiles. So my question is of it is possible to upload this data in bulk via an CSV?
You'll have to persist a import/export profile for your custom entity:
$container->get('import_export_profile.repository')->create([
[
'name' => 'My Custom Entity',
'label' => 'My Custom Entity',
'sourceEntity' => 'my_custom_entity',
'type' => ImportExportProfileEntity::TYPE_IMPORT_EXPORT,
'fileType' => 'text/csv',
'delimiter' => ';',
'enclosure' => '"',
'config' => [],
'mapping' => [
['key' => 'id', 'mappedKey' => 'id', 'position' => 1],
['key' => 'active', 'mappedKey' => 'active', 'position' => 2],
['key' => 'translations.DEFAULT.name', 'mappedKey' => 'name', 'position' => 3],
['key' => 'type', 'mappedKey' => 'type', 'position' => 0],
],
]
], $context);
There you have to map your entities fields to the columns of the CSV.
If you want to influence how fields are written or read you might want to register a serializer for your entity. For example the product entity has a serializer:
<service id="Shopware\Core\Content\ImportExport\DataAbstractionLayer\Serializer\Entity\ProductSerializer">
<!-- ... -->
<tag name="shopware.import_export.entity_serializer" priority="-400"/>
</service>
Maybe have a look at the serializer for reference if your entity has some fields that need special treatment.