Django streaming responses for large files

                  import csv
from django.http import StreamingHttpResponse, FileResponse


class Echo:
    """Helper for writing to streaming response."""
    def write(self, value):
        return value


def export_large_csv(request):
    """Stream large CSV without loading all data in memory."""

    def generate_rows():
        """Generator yielding CSV rows."""
        from products.models import Product

        # Yield header
        yield ['ID', 'Name', 'Price', 'Stock']

        # Stream products in chunks
        for product in Product.objects.iterator(chunk_size=1000):
            yield [
                str(product.id),
                product.name,
                str(product.price),
                str(product.stock)
            ]

    pseudo_buffer = Echo()
    writer = csv.writer(pseudo_buffer)
    rows = (writer.writerow(row) for row in generate_rows())

    response = StreamingHttpResponse(
        rows,
        content_type='text/csv'
    )
    response['Content-Disposition'] = 'attachment; filename="products.csv"'
    return response


def download_file(request, file_path):
    """Serve file download efficiently."""
    response = FileResponse(
        open(file_path, 'rb'),
        content_type='application/octet-stream'
    )
    response['Content-Disposition'] = f'attachment; filename="{os.path.basename(file_path)}"'
    return response