DecimalField – Django 模型
DecimalField 是一个存储固定精度十进制数的字段，在Python中由 Decimal 实例表示。它使用 DecimalValidator 验证输入。
句法
field_name = models.DecimalField(max_digits=None, decimal_places=None, **options)DecimalField 具有以下必需参数 -
DecimalField.max_digits
数字中允许的最大位数。请注意，此数字必须大于或等于 decimal_places。
DecimalField.decimal_places
与数字一起存储的小数位数。
例如，要以 2 个小数位的分辨率存储最大 999 的数字，您可以使用：
models.DecimalField(..., max_digits=5, decimal_places=2)并以小数点后 10 位的分辨率存储多达约 10 亿个数字：
models.DecimalField(..., max_digits=19, decimal_places=10)Django 模型小数字段说明
使用示例说明 DecimalField。考虑一个名为geeks的项目，它有一个名为geeksforgeeks的应用程序。
Refer to the following articles to check how to create a project and an app in Django.
- How to Create a Basic Project using MVT in Django?
- How to Create an App in Django ?
在极客应用的models.py文件中输入以下代码。
from django.db import models
from django.db.models import Model
# Create your models here.
class GeeksModel(Model):
geeks_field = models.DecimalField(
max_digits = 5,
decimal_places = 2)
将极客应用添加到INSTALLED_APPS
# Application definition
INSTALLED_APPS = [
'django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'geeks',
]
现在，当我们从终端运行makemigrations命令时，
Python manage.py makemigrations将在geeks目录中创建一个名为 migrations 的新文件夹，其中包含一个名为0001_initial.py的文件
# Generated by Django 2.2.5 on 2019-09-25 06:00
from django.db import migrations, models
class Migration(migrations.Migration):
initial = True
dependencies = [
]
operations = [
migrations.CreateModel(
name ='GeeksModel',
fields =[
('id',
models.AutoField(
auto_created = True,
primary_key = True,
serialize = False,
verbose_name ='ID'
)),
('geeks_field', models.DecimalField(
max_digits = 5,
decimal_places = 2
)),
],
),
]
现在运行，
Python manage.py migrate因此，当您在项目上运行迁移时，会创建一个geeks_field DecimalField 。它是一个存储datetime.date Python对象的字段。
如何使用小数域？
DecimalField 用于在数据库中存储Python datetime.date 实例。可以在数据库中存储任何类型的十进制数。让我们尝试在上面创建的模型中存储一个十进制数。
# importing the model
# from geeks app
from geeks.models import GeeksModel
# importing datetime module
import decimal
# creating an instance of
# datetime.date
d = decimal.Decimal(9.53)
# creating an instance of
# GeeksModel
geek_object = GeeksModel.objects.create(geeks_field = d)
geek_object.save()
现在让我们在管理服务器中检查它。我们已经创建了 GeeksModel 的一个实例。 
字段选项
字段选项是赋予每个字段的参数，用于应用某些约束或将特定特征赋予特定字段。例如，向 DecimalField 添加参数null = True将使其能够在关系数据库中存储该表的空值。
以下是 DecimalField 可以使用的字段选项和属性。
| Field Options | Description |
|---|---|
| Null | If True, Django will store empty values as NULL in the database. Default is False. |
| Blank | If True, the field is allowed to be blank. Default is False. |
| db_column | The name of the database column to use for this field. If this isn’t given, Django will use the field’s name. |
| Default | The default value for the field. This can be a value or a callable object. If callable it will be called every time a new object is created. |
| help_text | Extra “help” text to be displayed with the form widget. It’s useful for documentation even if your field isn’t used on a form. |
| primary_key | If True, this field is the primary key for the model. |
| editable | If False, the field will not be displayed in the admin or any other ModelForm. They are also skipped during model validation. Default is True. |
| error_messages | The error_messages argument lets you override the default messages that the field will raise. Pass in a dictionary with keys matching the error messages you want to override. |
| help_text | Extra “help” text to be displayed with the form widget. It’s useful for documentation even if your field isn’t used on a form. |
| verbose_name | A human-readable name for the field. If the verbose name isn’t given, Django will automatically create it using the field’s attribute name, converting underscores to spaces. |
| validators | A list of validators to run for this field. See the validators documentation for more information. |
| Unique | If True, this field must be unique throughout the table. |
在评论中写代码？请使用 ide.geeksforgeeks.org，生成链接并在此处分享链接。