Django：注釈付き日時のフィルタリング？

Question

私は、ユーザーにリンクされている（タイムスタンプ付き）一連のイベントがあります。私は、各ユーザ（後のサブクエリで使用される）のための最初のようなイベントのIDを検索したい

# models.py 

from django.db import models 

from django.contrib.auth.models import User 

class Event(models.Model): 
    name = models.CharField(max_length=255, blank=True, db_index=True) 
    time = models.DateTimeField(db_index=True) 
    user = models.ForeignKey(User, related_name='events', null=True) 

を。シンプルにする必要がありますか？

activation_event_ids = User.objects \ 
    .annotate(first_event_time=Min('events__time')) \ 
    .filter(events__time='first_event_time') \ 
    .values_list('events__id', flat=True) 

しかし、これが吹くまで：

ValidationError       Traceback (most recent call last) 
/home/gabriel/.virtualenvs/gordon/local/lib/python2.7/site-packages/django/core/management/commands/shell.pyc in <module>() 
     1 activation_event_ids = User.objects \ 
     2  .annotate(first_event_time=Min('km_events__time')) \ 
----> 3  .filter(km_events__time='first_event_time') \ 
     4  .values_list(km_events__id, flat=True) 

/home/gabriel/.virtualenvs/gordon/local/lib/python2.7/site-packages/django/db/models/query.pyc in filter(self, *args, **kwargs) 
    619   set. 
    620   """ 
--> 621   return self._filter_or_exclude(False, *args, **kwargs) 
    622 
    623  def exclude(self, *args, **kwargs): 

/home/gabriel/.virtualenvs/gordon/local/lib/python2.7/site-packages/django/db/models/query.pyc in _filter_or_exclude(self, negate, *args, **kwargs) 
    637    clone.query.add_q(~Q(*args, **kwargs)) 
    638   else: 
--> 639    clone.query.add_q(Q(*args, **kwargs)) 
    640   return clone 
    641 

/home/gabriel/.virtualenvs/gordon/local/lib/python2.7/site-packages/django/db/models/sql/query.pyc in add_q(self, q_object, used_aliases, force_having) 
    1251     else: 
    1252      self.add_filter(child, connector, q_object.negated, 
-> 1253        can_reuse=used_aliases, force_having=force_having) 
    1254     if force_having: 
    1255      self.having.end_subtree() 

/home/gabriel/.virtualenvs/gordon/local/lib/python2.7/site-packages/django/db/models/sql/query.pyc in add_filter(self, filter_expr, connector, negate, trim, can_reuse, process_extras, force_having) 
    1186   else: 
    1187    self.where.add((Constraint(alias, col, field), lookup_type, value), 
-> 1188     connector) 
    1189 
    1190   if negate: 

/home/gabriel/.virtualenvs/gordon/local/lib/python2.7/site-packages/django/db/models/sql/where.pyc in add(self, data, connector) 
    67 
    68   if hasattr(obj, "prepare"): 
---> 69    value = obj.prepare(lookup_type, value) 
    70    super(WhereNode, self).add((obj, lookup_type, annotation, value), 
    71     connector) 

/home/gabriel/.virtualenvs/gordon/local/lib/python2.7/site-packages/django/db/models/sql/where.pyc in prepare(self, lookup_type, value) 
    316  def prepare(self, lookup_type, value): 
    317   if self.field: 
--> 318    return self.field.get_prep_lookup(lookup_type, value) 
    319   return value 
    320 

/home/gabriel/.virtualenvs/gordon/local/lib/python2.7/site-packages/django/db/models/fields/__init__.pyc in get_prep_lookup(self, lookup_type, value) 
    707   if lookup_type in ('month', 'day', 'week_day'): 
    708    return int(value) 
--> 709   return super(DateField, self).get_prep_lookup(lookup_type, value) 
    710 
    711  def get_prep_value(self, value): 

/home/gabriel/.virtualenvs/gordon/local/lib/python2.7/site-packages/django/db/models/fields/__init__.pyc in get_prep_lookup(self, lookup_type, value) 
    308    return value 
    309   elif lookup_type in ('exact', 'gt', 'gte', 'lt', 'lte'): 
--> 310    return self.get_prep_value(value) 
    311   elif lookup_type in ('range', 'in'): 
    312    return [self.get_prep_value(v) for v in value] 

/home/gabriel/.virtualenvs/gordon/local/lib/python2.7/site-packages/django/db/models/fields/__init__.pyc in get_prep_value(self, value) 
    799 
    800  def get_prep_value(self, value): 
--> 801   value = self.to_python(value) 
    802   if value is not None and settings.USE_TZ and timezone.is_naive(value): 
    803    # For backwards compatibility, interpret naive datetimes in local 


/home/gabriel/.virtualenvs/gordon/local/lib/python2.7/site-packages/django/db/models/fields/__init__.pyc in to_python(self, value) 
    783 
    784   msg = self.error_messages['invalid'] % value 
--> 785   raise exceptions.ValidationError(msg) 
    786 
    787  def pre_save(self, model_instance, add): 

ValidationError: [u"'first_event_time' value has an invalid format. It must be in YYYY-MM-DD HH:MM[:ss[.uuuuuu]][TZ] format."] 

私は現在、ローカルのSQLite DBを使用しています。注釈付きの日時をフィルタリングすることは本当に不可能ですか？あるいは、何かばかげているだけですか？

ありがとうございます！

Answer 1

あなたは注釈フィールドを参照する場合は、Fを使用する必要があります。

参考

from django.db.models import F 

... 

.filter(events__time=F('first_event_time')) 

、以下を参照してくださいhttps://docs.djangoproject.com/en/dev/topics/db/queries/#query-expressions