workx_backend/invoice/serializers.py

from rest_framework import serializers
from drf_writable_nested.serializers import WritableNestedModelSerializer
from .models import Item, Invoice
from project.serializers import ProjectSerializer


class ItemSerializer(serializers.ModelSerializer):
    class Meta:
        model = Item
        fields = ['id', 'name', 'amount', 'quantity', 'invoice', 'item_total']


class InvoiceSerializer(WritableNestedModelSerializer):
    project = ProjectSerializer(read_only=True)
    items = ItemSerializer(many=True)

    class Meta:
        model = Invoice
        fields = ['id', 'title', 'project', 'invoice_id', 'raised_date', 'due_date', 'paid_date', 'is_archived',
                  'invoice_total_with_tax', 'items']