筛选通用外键

Steph 发表于 Dev

斯蒂芬

有没有更多的“ Python / Django”方法可以通过通用外键查询/过滤对象？我正在尝试获取特定软件的所有FullCitation对象，其中is_primary为True。

我知道我做不到，但我想做这样的事情：

ct_supported = ContentType.objects.get(app_label="supportedprogram", model="software")
primary_citations = FullCitation.objects.filter(content_type__name=ct_supported, object_id__in='', is_primary=True)

models.py

class FullCitation(models.Model)
    # the software to which this citation belongs
    # either a supported software program or a non-supported software program

    limit = models.Q(app_label = 'myprograms', model = 'supportedprogram') | models.Q(app_label = 'myprograms', model = 'nonsupportedprogram') 
    content_type = models.ForeignKey(ContentType), limit_choices_to = limit, )
    object_id = models.PositiveIntegerField()
    content_object = generic.GenericForeignKey('content_type', 'object_id')

    is_primary = models.BooleanField(help_text="Is this the Primary Citation for the software program?")

class NonSupportedProgram(models.Model):
    title = models.CharField(max_length=256, blank = True)
    full_citation = generic.GenericRelation('FullCitation')

class SupportedProgram(models.Model):
    title = models.CharField(max_length=256, blank = True)
    full_citation = generic.GenericRelation('FullCitation')
    # and a bunch of other fields.....

views.py＃我目前的尝试

primary_citations = []
sw_citations = sw.full_citations.all()
    for x in sw_citations:
        if x.is_primary:
            primary_citations.append(x)

洪水

理解应该是筛选QuerySet的最后手段。最好让它们尽可能长地保留为QuerySet。我认为这是您要寻找的：

ct_supported = ContentType.objects.get_for_model(SupportedProgram))
primary_citations = FullCitation.objects.filter(content_type=ct_supported, is_primary=True)

更新：如果要筛选特定的SupportedProgram实例，请执行以下操作：

my_supported = SupportedProgram.objects.get(id=instance_id_goes_here)
ct_supported = ContentType.objects.get_for_model(SupportedProgram))
primary_citations = FullCitation.objects.filter(content_object=my_supported, content_type=ct_supported, is_primary=True)

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