Question

我有3个型号：

    : execute('r! '.myscript.path.variablename)

我想过滤stations.objects（并获取其字段），使其仅包含给定route_id的站点。到目前为止，我只能写这一行，我猜这是错误的class stations(models.Model): station_id = models.AutoField( primary_key=True ) station = models.CharField( max_length=20 ) station_code = models.CharField( max_length=10 ) class route(models.Model): route_id = models.AutoField( primary_key=True ) class SequenceTable(models.Model): id = models.AutoField( primary_key=True ) route_id = models.ForeignKey( route, on_delete=models.CASCADE) station_id = models.ForeignKey(stations, on_delete=models.CASCADE) sequence_no = models.IntegerField( null=True )

请帮我找到正确的解决方案

Answer 1

你可以这样做。

station_ids = SequenceTable.objects.filter(route_id=rid).values_list('station_id', flat=True)

station_qs = stations.objects.filter(station_id__in=station_ids)

由于django的查询集的实现方式，这将只生成一个数据库查询。

回答评论。是的，你可以在这里（可能行不通）会给你一般的想法

def station_gen(rid):
    triple = []
    station_ids = SequenceTable.objects.filter(route_id=rid).values_list('station_id', flat=True)
    for s in stations.objects.filter(station_id__in=station_ids):
        if len(triple) == 3:
            triple.pop(0)
            triple.append(s)
            yield triple
        else:
            triple.append(s)

# and inside your view
...
if request.method == 'POST':
    rid = request.POST.get('rid',None)
    for three_students in student_gen(rid):
        ...
    print(three_students)

使用另一个table-django的filterset过滤表的模型

1 个答案: