Please help me decipher a traceback for "ValueError: invalid literal for int()" in my models

Question

我正在尝试创建 ProductPart 个对象的列表，其中 ProductPart.part 与 Variety.variety_name 的实例值相匹配。这是我的问题的演示。

> v = Variety.objects.get(id=2)
> p = ProductPart.objects.get(id=1)
> v.variety_name
'Non Pareil (Inshell)'
> p.part
<Variety: Non Pareil (Inshell)>
> a = ProductPart.objects.values().filter(part=v.variety_name)
...
ValueError: invalid literal for int() with base 10: 'Non Pareil (Inshell)'

此模式似乎适用于我的模型的其他地方，但出于某种原因，它不适用于此处。有谁知道我做错了什么？有人能帮我理解为什么它要获取 int() 对象吗？

回溯：

Traceback (most recent call last):
File "<input>", line 1, in <module>
File "C:\Projects\AlmondKing\AlmondKing\InventoryLogs\models.py", line 49, in _total_sales_of_variety
  sold = ProductPart.objects.values().filter(part=self.variety_name)
File "C:\Users\Adam\Envs\AlmondKing\lib\site-packages\django\db\models\query.py", line 679, in filter
  return self._filter_or_exclude(False, *args, **kwargs)
File "C:\Users\Adam\Envs\AlmondKing\lib\site-packages\django\db\models\query.py", line 697, in _filter_or_exclude
  clone.query.add_q(Q(*args, **kwargs))
File "C:\Users\Adam\Envs\AlmondKing\lib\site-packages\django\db\models\sql\query.py", line 1304, in add_q
  clause, require_inner = self._add_q(where_part, self.used_aliases)
File "C:\Users\Adam\Envs\AlmondKing\lib\site-packages\django\db\models\sql\query.py", line 1332, in _add_q
  allow_joins=allow_joins, split_subq=split_subq,
File "C:\Users\Adam\Envs\AlmondKing\lib\site-packages\django\db\models\sql\query.py", line 1194, in build_filter
  lookups, value)
File "C:\Users\Adam\Envs\AlmondKing\lib\site-packages\django\db\models\fields\related.py", line 1740, in get_lookup_constraint
   ookup_class(target.get_col(alias, source), val), AND)
File "C:\Users\Adam\Envs\AlmondKing\lib\site-packages\django\db\models\lookups.py", line 96, in __init__
  self.rhs = self.get_prep_lookup()
File "C:\Users\Adam\Envs\AlmondKing\lib\site-packages\django\db\models\lookups.py", line 134, in get_prep_lookup
  return self.lhs.output_field.get_prep_lookup(self.lookup_name, self.rhs)
File "C:\Users\Adam\Envs\AlmondKing\lib\site-packages\django\db\models\fields\__init__.py", line 727, in get_prep_lookup
  return self.get_prep_value(value)
File "C:\Users\Adam\Envs\AlmondKing\lib\site-packages\django\db\models\fields\__init__.py", line 985, in get_prep_value
  return int(value)
ValueError: invalid literal for int() with base 10: 'Non Pareil (Inshell)'

型号：

class Variety(models.Model):
    product_group = models.ForeignKey(ProductGroup)
    variety_name = models.CharField(max_length=140)
    husked = models.BooleanField()
    finished = models.BooleanField() #defunct
    description = models.CharField(max_length=500, blank=True)

class ProductPart(models.Model):
    product = models.ForeignKey(Product)
    part = models.ForeignKey(Variety)
    qty = models.DecimalField(max_digits=28, decimal_places=2)

Answer 1

您正在尝试将外键与字符串匹配，您需要提供模型

ProductPart.objects.values().filter(part=v)

注意：values 也不是必需的

ProductPart.objects.filter(part=v)

来自 Values

的文档

a QuerySet subclass that returns dictionaries when used as an iterable, rather than model-instance objects.

换句话说，您正在失去对当前方法的对象的一些控制

Answer 2

根据 Django ORM，您应该直接在过滤器中处理模型对象（它使代码易于阅读）

v = Variety.objects.get(id=2)
a = ProductPart.objects.filter(part=v)

Answer 3

这是当您尝试将字符串解析为 int 并且不是有效整数时遇到的错误：int('hello')

您正试图在此查询中做一些奇怪的事情：

a = ProductPart.objects.values().filter(part=v.variety_name)

基本上，part 是 Variety 的外键（在这种情况下，外键是一个整数），您正试图将它与字符串 v.variety_name 进行比较。

我认为正确的做法是这样的：

a = ProductPart.objects.filter(part=v)

Answer 4

你应该使用：

a = ProductPart.objects.values().filter(part__variety_name=v.variety_name)

查看此 Django 文档 Lookups that span relationships

Please help me decipher a traceback for "ValueError: invalid literal for int()" in my models

Please help me decipher a traceback for "ValueError: invalid literal for int()" in my models

django

django-middleware

django-models