input: Write a python function to add a new item to the database and retrieve all items using Django ORM.
  assert add_and_get_items('item1', 10) == [{'name': 'item1', 'amount': 10}]
  assert add_and_get_items('item2', 20) == [{'name': 'item1', 'amount': 10}, {'name': 'item2', 'amount': 20}]
  assert add_and_get_items('item3', 30) == [{'name': 'item1', 'amount': 10}, {'name': 'item2', 'amount': 20}, {'name': 'item3', 'amount': 30}]
output: def add_and_get_items(name, amount):
      from django.db import models
  
      class Item(models.Model):
          name = models.CharField(max_length=255)
          amount = models.IntegerField()
  
      # Add new item to the database
      Item.objects.create(name=name, amount=amount)
  
      # Retrieve all items from the database
      items = Item.objects.all().values('name', 'amount')
      return list(items)