使用 select_related() 的 Django 过滤器答案

【问题标题】：Django filter using select_related()使用 select_related() 的 Django 过滤器
【发布时间】：2016-12-20 22:08:39
【问题描述】：

我有以下完美的查询：

    campaignFixtures = UserSelection.objects.select_related().filter(user=currentUserID,campaignno=currentCampaignNo).order_by('fixtureid__fixturedate')[:1]

但是，我需要从另一个表中过滤一个字段，如下所示：

    campaignFixtures = UserSelection.objects.select_related().filter(user=currentUserID,campaignno=currentCampaignNo,straightredfixture__fixturematchday=18).order_by('fixtureid__fixturedate')[:1]

但是，我收到以下错误：

Cannot resolve keyword 'straightredfixture' into field. Choices are: campaignno, fixtureid, fixtureid_id, teamselection1or2, teamselectionid, teamselectionid_id, user, user_id, userselectionid

型号如下：

class StraightredFixture(models.Model):
    fixtureid = models.IntegerField(primary_key=True)
    home_team = models.ForeignKey('straightred.StraightredTeam', db_column='hometeamid', related_name='home_fixtures')
    away_team = models.ForeignKey('straightred.StraightredTeam', db_column='awayteamid', related_name='away_fixtures')
    fixturedate = models.DateTimeField(null=True)
    fixturestatus = models.CharField(max_length=24,null=True)
    fixturematchday = models.ForeignKey('straightred.StraightredFixtureMatchday', db_column='fixturematchday')
    spectators = models.IntegerField(null=True)
    hometeamscore = models.IntegerField(null=True)
    awayteamscore = models.IntegerField(null=True)
    homegoaldetails = models.TextField(null=True)
    awaygoaldetails = models.TextField(null=True)
    hometeamyellowcarddetails = models.TextField(null=True)
    awayteamyellowcarddetails = models.TextField(null=True)
    hometeamredcarddetails = models.TextField(null=True)
    awayteamredcarddetails = models.TextField(null=True)
    soccerseason = models.ForeignKey('straightred.StraightredSeason', db_column='soccerseasonid', related_name='fixture_season')


    def __unicode__(self):
        return self.fixtureid

    class Meta:
        managed = True
        db_table = 'straightred_fixture'

class UserSelection(models.Model):
    userselectionid = models.AutoField(primary_key=True)
    campaignno = models.CharField(max_length=36,unique=False)
    user = models.ForeignKey(User, related_name='selectionUser')
    teamselection1or2 = models.PositiveSmallIntegerField()
    teamselectionid = models.ForeignKey('straightred.StraightredTeam', db_column='teamselectionid', related_name='teamID')
    fixtureid = models.ForeignKey('straightred.StraightredFixture', db_column='fixtureid')


    class Meta:
        managed = True
        db_table = 'straightred_userselection'

任何帮助都将不胜感激，艾伦。

【问题讨论】：

标签： sql django django-models

【解决方案1】：

我认为问题与selected_related 无关。您只是尝试使用错误的查找值进行过滤。用fixtureid__fixturematchday 过滤怎么样：

UserSelection.objects.select_related().filter(user=currentUserID, campaignno=currentCampaignNo, fixtureid__fixturematchday=18).order_by('fixtureid__fixturedate')[:1]

既然你只想获取一个对象，为什么不直接使用.first() 来获取一个对象而不是一个包含一个项目的查询集：

campaignFixture = UserSelection.objects.select_related("fixtureid").filter(...).order_by(...).first()

【讨论】：

非常感谢，我是如此接近。非常感谢您提供的其他信息。
真的，这表明您应该更改模型中的字段名称。

【解决方案2】：

根据你的模型，关系是fixtureid

 UserSelection.objects.select_related().filter(user=currentUserID,campaignno=currentCampaignNo,fixtureid__fixturematchday=18)

【讨论】：

@alantingey - 不用担心，您唯一需要类名的时候是当您通过未指定相关名称的反向关系查找时