How to sort date by day?

Question

Django

Metric.objects.filter().order_by('-date__week_day')[:7]

__week_day swears
How to sort so that there is an order from Mon to Sun. I am using django 1.10
model itself
date = models.DateField(default=timezone.now())

Traceback (most recent call last):
  File "/home/abc/lib/python3.4/site-packages/django/core/handlers/exception.py", line 42, in inner
    response = get_response(request)
  File "/home/abc/lib/python3.4/site-packages/django/core/handlers/base.py", line 187, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "/home/abc/lib/python3.4/site-packages/django/core/handlers/base.py", line 185, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/home/abc/back/statistic/views.py", line 98, in graph
    for i in m:
  File "/home/abc/lib/python3.4/site-packages/django/db/models/query.py", line 256, in __iter__
    self._fetch_all()
  File "/home/abc/lib/python3.4/site-packages/django/db/models/query.py", line 1087, in _fetch_all
    self._result_cache = list(self.iterator())
  File "/home/abc/lib/python3.4/site-packages/django/db/models/query.py", line 54, in __iter__
    results = compiler.execute_sql()
  File "/home/abc/lib/python3.4/site-packages/django/db/models/sql/compiler.py", line 824, in execute_sql
    sql, params = self.as_sql()
  File "/home/abc/lib/python3.4/site-packages/django/db/models/sql/compiler.py", line 369, in as_sql
    extra_select, order_by, group_by = self.pre_sql_setup()
  File "/home/abc/lib/python3.4/site-packages/django/db/models/sql/compiler.py", line 47, in pre_sql_setup
    order_by = self.get_order_by()
  File "/home/abc/lib/python3.4/site-packages/django/db/models/sql/compiler.py", line 293, in get_order_by
    field, self.query.get_meta(), default_order=asc))
  File "/home/abc/lib/python3.4/site-packages/django/db/models/sql/compiler.py", line 553, in find_ordering_name
    field, targets, alias, joins, path, opts = self._setup_joins(pieces, opts, alias)
  File "/home/abc/lib/python3.4/site-packages/django/db/models/sql/compiler.py", line 586, in _setup_joins
    pieces, opts, alias)
  File "/home/abc/lib/python3.4/site-packages/django/db/models/sql/query.py", line 1402, in setup_joins
    names, opts, allow_many, fail_on_missing=True)
  File "/home/abc/lib/python3.4/site-packages/django/db/models/sql/query.py", line 1370, in names_to_path
    " not permitted." % (names[pos + 1], name))
django.core.exceptions.FieldError: Cannot resolve keyword 'week_day' into field. Join on 'date' not permitted.
[22/Mar/2017 11:47:53] "GET /graph HTTP/1.1" 500 111277