我正在尝试验证具有“可选”字段的对象,这些字段可能存在也可能不存在。但是,当存在字段时,这些字段应符合特定的类型定义(不是None)。
在下面的示例中,“大小”字段是可选的,但不允许“无”。我希望“大小”字段为可选,但如果存在,则应为浮点数。
from pydantic import BaseModel
class Foo(BaseModel):
count: int
size: float = None # how to make this an optional float?
>>> Foo(count=5)
Foo(count=5, size=None) # GOOD - "size" is not present, value of None is OK
>>> Foo(count=5, size=None)
Foo(count=5, size=None) # BAD - if field "size" is present, it should be a float
# BONUS
>>> Foo(count=5)
Foo(count=5) # BEST - "size" is not present, it is not required to be present, so we don't care about about validating it all. We are using Foo.json(exclude_unset=True) handles this for us which is fine.
可以与validator一起使用。
from pydantic import BaseModel, ValidationError, validator
class Foo(BaseModel):
count: int
size: float = None
@validator('size')
def size_is_some(cls, v):
if v is None:
raise ValueError('Cannot set size to None')
return float(v)
这将按预期工作:
>>> Foo(count=5)
Foo(count=5, size=None)
>>> Foo(count=5, size=1.6)
Foo(count=5, size=1.6)
>>> Foo(count=5, size=None)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "[venv]/lib/python3.6/site-packages/pydantic/main.py", line 283, in __init__
raise validation_error
pydantic.error_wrappers.ValidationError: 1 validation error for Foo
size
Cannot set size to None (type=value_error)