Django在save（）方法之后而不是更新之后插入新对象 [英] Django inserts new object after save() method instead of update

问题描述

当尝试 更新 （使用 save（）方法）的现有Django模型对象时，<而是插入了strong> 新 行。

When trying to update an existing Django model object (with the save() method), a new row is inserted instead.

例如：

>>> import datetime
>>> from data_lib.models import Meal
>>> m = Meal(name="My First Meal!", description="this is my first meal's description")
>>> print m.mealid
None
>>> m.save()
>>> print m.mealid
None
>>> m.save()

第二次 save（）方法调用，将重复的条目插入到我的表中。

after that second save() method call, a duplicate entry was inserted into my table.

这是模型定义的示例：

here is a sample of the model definition:

class Meal(models.Model):
    mealid = models.IntegerField(db_column='MealId', primary_key=True)
    name = models.CharField(db_column='Name', max_length=45, blank=True)
    description = models.CharField(db_column='Description', max_length=200, blank=True)

推荐答案

来自Django文档（ 1 ， 2 ）：

From the Django docs (1, 2):

主键字段是只读的。如果更改现有对象上的主键的值然后保存，则将与旧对象一起创建一个新对象。

The primary key field is read-only. If you change the value of the primary key on an existing object and then save it, a new object will be created alongside the old one.

< hr>

问题出在模型对象的类定义中。



将primary_key字段设置为 AutoField 后，问题就消失了。


我的新模型定义如下：

---

The issue was in the model object's class definition.

Once I set the primary_key field to an AutoField, the issue went away.

My new model definition is as follows:

class Meal(models.Model):
        mealid = models.AutoField(db_column='MealId', primary_key=True)
        name = models.CharField(db_column='Name', max_length=45, blank=True)
        description = models.CharField(db_column='Description', max_length=200, blank=True)

---

Django完美的自动生成功能！

---

An almost perfect auto-generation by Django!

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