-class ChunksList(object):
- def __init__(self, chunk_qs):
- self.chunk_qs = chunk_qs.annotate(
- book_length=Count('book__chunk')).select_related(
- 'book', 'stage__name',
- 'user')
-
- self.book_qs = chunk_qs.values('book_id')
-
- def __getitem__(self, key):
- if isinstance(key, slice):
- return self.get_slice(key)
- elif isinstance(key, int):
- return self.get_slice(slice(key, key+1))[0]
- else:
- raise TypeError('Unsupported list index. Must be a slice or an int.')
-
- def __len__(self):
- return self.book_qs.count()
-
- def get_slice(self, slice_):
- book_ids = [x['book_id'] for x in self.book_qs[slice_]]
- chunk_qs = self.chunk_qs.filter(book__in=book_ids)
-
- chunks_list = []
- book = None
- for chunk in chunk_qs:
- if chunk.book != book:
- book = chunk.book
- chunks_list.append(ChoiceChunks(book, [chunk], chunk.book_length))
- else:
- chunks_list[-1].chunks.append(chunk)
- return chunks_list
-
-
-class ChoiceChunks(object):
- """
- Associates the given chunks iterable for a book.
- """
-
- chunks = None
-
- def __init__(self, book, chunks, book_length):
- self.book = book
- self.chunks = chunks
- self.book_length = book_length
-
+def cached_in_field(field_name):
+ def decorator(f):
+ @property
+ @wraps(f)
+ def wrapped(self, *args, **kwargs):
+ value = getattr(self, field_name)
+ if value is None:
+ value = f(self, *args, **kwargs)
+ type(self)._default_manager.filter(pk=self.pk).update(**{field_name: value})
+ return value
+ return wrapped
+ return decorator