Python 将 django FloatField 限制为 2 个小数位
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Restrict django FloatField to 2 decimal places
提问by Aidan Doherty
I am looking for a way to limit the FloatField in Django to 2 decimal places has anyone got a clue of how this could be done without having to use a DecimalField.
我正在寻找一种方法来将 Django 中的 FloatField 限制为 2 个小数位，有没有人知道如何在不使用 DecimalField 的情况下完成此操作。
I tried decimal_places=2but this was just giving me a migration error within the float field so i am thinking this method must only work within DecimalFields.
我试过了，decimal_places=2但这只是在浮点字段中给我一个迁移错误，所以我认为这个方法只能在 DecimalFields 中工作。
采纳答案by pcoronel
If you are only concerned with how your FloatFieldappears in forms, you can use the template filter floatformat.
如果您只关心您FloatField在表单中的显示方式，则可以使用模板过滤器floatformat。
From the Django Docs:
来自 Django 文档：
If used with a numeric integer argument, floatformat rounds a number to that many decimal places.
如果与数字整数参数一起使用，则 floatformat 会将数字四舍五入到那么多小数位。
For example, if value = 34.23234, then in your template:
例如，如果 value = 34.23234，则在您的模板中：
{{ value|floatformat:2 }} # outputs 34.23
回答by Catalin
Since Django 1.8+ you can use a custom validator for FloatField/or any ModelFields:
从 Django 1.8+ 开始，您可以为 FloatField/或任何 ModelField 使用自定义验证器：
def validate_decimals(value):
try:
return round(float(value), 2)
except:
raise ValidationError(
_('%(value)s is not an integer or a float number'),
params={'value': value},
)
...and in your model you can apply it like this:
...在您的模型中，您可以像这样应用它：
from django.db import models
class MyModel(models.Model):
even_field = models.FloatField(validators=[validate_decimals])
回答by Colton Hicks
If you'd like to actually ensure that your model always gets saved with only two decimal places, rather than just changing the presentation of the model in a template, a custom save method on your model will work great. The example model below shows how.
如果您想真正确保您的模型始终只保存两位小数，而不是仅仅更改模板中模型的表示，那么模型上的自定义保存方法将非常有用。下面的示例模型显示了如何。
class MyDataModel(models.Model):
my_float = models.FloatField()
def save(self, *args, **kwargs):
self.my_float = round(self.my_float, 2)
super(MyDataModel, self).save(*args, **kwargs)
Now every time you save your model you will guarantee that the field will only be populated with a float of two decimal places. This can be generalized to rounding to any number of decimal places.
现在，每次保存模型时，您都将保证该字段将只填充两位小数的浮点数。这可以概括为四舍五入到任意数量的小数位。
