访问my for Statemens数据库中的特定项

Question

我有一个有点奇怪的情况。我使用的是一个只读数据库，我可以通过我的物业管理软件访问。它们允许用户在软件中定义字段。但是，它们不会在数据库中显示为特定字段。数据库有两个相关的表propuserdefined和propuserdefinedvalues。propuserdefined包含有关字段的所有信息（id、名称、描述）propuserdiefinedvalues包含与属性关联的值。它有propid、userdefinedid和value。我的问题是，我需要访问propuserdefinedvalues的值，其中propid等于我的for property in properties语句中的propid，userdefinedid等于49。我该怎么做？有模板标签吗？你知道吗

提前感谢您的帮助。
布兰登

这是我的模型。你知道吗

class Propuserdefined(models.Model):
    userdefinedid = models.IntegerField(primary_key=True)
    name = models.CharField(max_length=50L, blank=True)
    type = models.IntegerField()
    userid = models.IntegerField(null=True, blank=True)
    updated = models.DateTimeField(null=True, blank=True)
    datecreated = models.DateTimeField(null=True, blank=True)
    combolist = models.TextField(blank=True)
    class Meta:
        db_table = 'propuserdefined'

class Propuserdefinedvalues(models.Model):
    userdefinedid = models.IntegerField()
    propid = models.IntegerField()
    value = models.TextField(blank=True)
    userid = models.IntegerField(null=True, blank=True)
    updated = models.DateTimeField(null=True, blank=True)
    datecreated = models.DateTimeField(null=True, blank=True)
    class Meta:
        db_table = 'propuserdefinedvalues'

class Property(models.Model):
    propid = models.IntegerField(primary_key=True)
    name = models.CharField(max_length=35L, blank=True)
    shortname = models.CharField(max_length=6L, blank=True)
    street1 = models.CharField(max_length=50L, blank=True)
    street2 = models.CharField(max_length=50L, blank=True)
    city = models.CharField(max_length=50L, blank=True)
    state = models.CharField(max_length=2L, blank=True)
    zip = models.CharField(max_length=50L, blank=True)
    phone = models.CharField(max_length=21L, blank=True)
    fax = models.CharField(max_length=50L, blank=True)
    email = models.CharField(max_length=255L, blank=True)
    manager = models.CharField(max_length=25L, blank=True)
    billname1 = models.CharField(max_length=35L, blank=True)
    billname2 = models.CharField(max_length=35L, blank=True)
    billstreet1 = models.CharField(max_length=50L, blank=True)
    billstreet2 = models.CharField(max_length=50L, blank=True)
    billcity = models.CharField(max_length=50L, blank=True)
    billstate = models.CharField(max_length=2L, blank=True)
    billzip = models.CharField(max_length=50L, blank=True)
    proptaxid = models.CharField(max_length=35L, blank=True)
    rentchargetype = models.CharField(max_length=20L, blank=True)
    lastpostdate = models.DateField(null=True, blank=True)
    lastweeklypostdate = models.DateField(null=True, blank=True)
    comments = models.CharField(max_length=25L, blank=True)
    enablespeciallatecharge = models.IntegerField(null=True, blank=True)
    fixedlatecharge = models.IntegerField(null=True, blank=True)
    fixedlateamount = models.FloatField(null=True, blank=True)
    fixedlaterentonly = models.IntegerField(null=True, blank=True)
    percentlate = models.IntegerField(null=True, blank=True)
    percentlateamount = models.FloatField(null=True, blank=True)
    percentlatefullcharge = models.IntegerField(null=True, blank=True)
    percentlaterentonly = models.IntegerField(null=True, blank=True)
    perdaylate = models.IntegerField(null=True, blank=True)
    perdaylateamount = models.FloatField(null=True, blank=True)
    perdaylategrace = models.IntegerField(null=True, blank=True)
    perdaylategracenum = models.IntegerField(null=True, blank=True)
    perdatelatelimitamount = models.FloatField()
    perdaylategracenonretro = models.IntegerField()
    perdaylategraceexclweekends = models.IntegerField()
    perdaylategraceexclholidays = models.IntegerField()
    datecreated = models.DateTimeField(null=True, blank=True)
    updated = models.DateTimeField(null=True, blank=True)
    userid = models.IntegerField(null=True, blank=True)
    logofile = models.CharField(max_length=255L, blank=True)
    merchantid = models.CharField(max_length=255L, blank=True)
    epaybankid = models.IntegerField()
    epaylimit = models.FloatField()
    epayenabled = models.IntegerField()
    achconveniencefeeenabled = models.IntegerField()
    ccconveniencefeeenabled = models.IntegerField()
    rwaachconvenciencefeeenabled = models.IntegerField()
    rwaccconveniencefeeenabled = models.IntegerField()
    epayislimited = models.IntegerField()
    epayusedefaults = models.IntegerField()
    achconveniencefee = models.FloatField(null=True, blank=True)
    ccconveniencefee = models.FloatField(null=True, blank=True)
    rwaachconveniencefee = models.FloatField(null=True, blank=True)
    rwaccconveniencefee = models.FloatField(null=True, blank=True)
    epaychargetype = models.IntegerField()
    epayamounttype = models.IntegerField()
    epaysetamount = models.FloatField()
    epaycustlimit = models.FloatField()
    sqft = models.IntegerField()
    lateminbalance = models.FloatField(null=True, blank=True)
    defaultbank = models.IntegerField()
    postday = models.IntegerField(null=True, blank=True)
    active = models.IntegerField(null=True, blank=True)
    iscommercial = models.IntegerField(null=True, blank=True)
    assignedissueuserid = models.IntegerField(null=True, blank=True)
    altname = Propuserdefinedvalues.objects.filter(userdefinedid=49)
    class Meta:
        db_table = 'property'

Answer 1

按原样使用模型（没有定义ForeignKeys，因此不能使用ORM跟踪关系），您可以获得如下详细信息（如果我正确理解了您的问题）：

property = Property.objects.get(name='my_property_name') # or however you get the property
prop_user_defined_values = Propuserdefinedvalues.objects.filter(propid=property.id, userdefinedid=49)

但是，如果您更改模型的顺序，并将某些字段键入ForiegnKey，则这可能会缩短：

class Property(models.Model):
    # ... rest truncated ...

class Propuserdefined(models.Model):
    # ... rest truncated ...

class Propuserdefinedvalues(models.Model):
    property = models.ForeignKey(Property, db_column='propid')
    userdefined = models.ForeignKey(Propuserdefined, db_column='userdefinedid')
    # ... rest truncated ...

这将允许您执行以下操作：

Propuserdefinedvalues.objects.filter(userdefined__name='my_name', property__name='my_property')
# or:
my_property = Property.objects.get(name='my_property')
Propuserdefinedvalues.objects.filter(userdefined__userdefinedid=49, property=my_property)

我建议您在这里阅读Django的模型：https://docs.djangoproject.com/en/1.5/topics/db/models/-它们很容易得到正确的结果，即使您有预先存在的表，只要您知道它们之间的关系。你知道吗

（免责声明：未经测试的代码！可能是虫子；））

Answer 2

听起来像是在Django模板中尝试这样做。您应该改为使用Python代码，因为Django模板不是为此而设计的。你知道吗

表的Django模型也不能提供访问这些属性的最佳接口。相反，您应该在它们之上创建一些函数。或者，您可以编写原始SQL来跨两个表进行连接。你知道吗