Django datetime.datetime转为十进制不支持迁移

Question

下面是我试图迁移时即将出现的模型和错误。我正在使用django 1.10，当我尝试迁移时，我的数据库是空的。

型号：

from django.db import models 

class OrderEntry(models.Model): 
    quote_num = models.CharField(max_length=50, primary_key=True) 
    customer = models.CharField(max_length=100) 
    cust_po = models.CharField(max_length=50) 
    pdf = models.CharField(max_length=500) 
    datetime = models.DateTimeField(auto_now=True, editable=True, null=True) 

class Items(models.Model): 
    quote_num = models.CharField(max_length=50, primary_key=True) 
    item_1 = models.CharField(max_length=100) 
    item_2 = models.CharField(max_length=100) 
    item_3 = models.CharField(max_length=100) 
    item_4 = models.CharField(max_length=100) 
    item_5 = models.CharField(max_length=100) 
    item_6 = models.CharField(max_length=100) 
    item_7 = models.CharField(max_length=100) 
    item_8 = models.CharField(max_length=100) 
    item_9 = models.CharField(max_length=100) 
    item_10 = models.CharField(max_length=100) 

class ItemDetails(models.Model): 
    item = models.CharField(max_length=100, primary_key=True) 
    quote_num = models.CharField(max_length=50) 
    quan = models.CharField(max_length=100) 
    desc = models.TextField(max_length=1000) 
    price = models.DecimalField(max_digits=10, decimal_places=2, default=0, null=True) 

错误：

C:\Users\Evan\Desktop\webapp>py manage.py migrate 
Operations to perform: 
Apply all migrations: admin, auth, contenttypes, orders, sessions 

Running migrations: 
    Applying orders.0013_itemdetails_price...Traceback (most recent call last): 
    File "manage.py", line 22, in <module> 
    execute_from_command_line(sys.argv) 
    File "C:\Users\Evan\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\core\management\__init__.py", line 367, in execute_from_command_line 
    utility.execute() 
    File "C:\Users\Evan\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\core\management\__init__.py", line 359, in execute 
    self.fetch_command(subcommand).run_from_argv(self.argv) 
    File "C:\Users\Evan\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\core\management\base.py", line 294, in run_from_argv 
    self.execute(*args, **cmd_options) 
    File "C:\Users\Evan\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\core\management\base.py", line 345, in execute 
    output = self.handle(*args, **options) 
    File "C:\Users\Evan\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\core\management\commands\migrate.py", line 204, in handle 
    fake_initial=fake_initial, 
    File "C:\Users\Evan\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\migrations\executor.py", line 115, in migrate 
    state = self._migrate_all_forwards(state, plan, full_plan, fake=fake, fake_initial=fake_initial) 
    File "C:\Users\Evan\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\migrations\executor.py", line 145, in _migrate_all_forwards 
    state = self.apply_migration(state, migration, fake=fake, fake_initial=fake_initial) 
    File "C:\Users\Evan\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\migrations\executor.py", line 244, in apply_migration 
    state = migration.apply(state, schema_editor) 
    File "C:\Users\Evan\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\migrations\migration.py", line 129, in apply 
    operation.database_forwards(self.app_label, schema_editor, old_state, project_state) 
    File "C:\Users\Evan\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\migrations\operations\fields.py", line 84, in database_forwards 
    field, 
    File "C:\Users\Evan\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\backends\postgresql\schema.py", line 21, in add_field 
    super(DatabaseSchemaEditor, self).add_field(model, field) 
    File "C:\Users\Evan\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\backends\base\schema.py", line 395, in add_field 
    definition, params = self.column_sql(model, field, include_default=True) 
    File "C:\Users\Evan\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\backends\base\schema.py", line 147, in column_sql 
    default_value = self.effective_default(field) 
    File "C:\Users\Evan\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\backends\base\schema.py", line 221, in effective_default 
    default = field.get_db_prep_save(default, self.connection) 
    File "C:\Users\Evan\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\models\fields\__init__.py", line 1583, in get_db_prep_save 
    return connection.ops.adapt_decimalfield_value(self.to_python(value), self.max_digits, self.decimal_places) 
    File "C:\Users\Evan\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\models\fields\__init__.py", line 1554, in to_python 
    return decimal.Decimal(value) 
TypeError: conversion from datetime.datetime to Decimal is not supported 

我已经设置一些默认值和空值，试图迁移到postgre数据库。谢谢你的帮助。

Answer 1

您的错误消息导致我相信您错误地将价格字段设置为DateTimeField，现在您正在尝试更改它。这与您在psql控制台中执行像这样的语句时得到的错误一致。

ALTER TABLE item_details ALTER COLUMN price SET TYPE DECIMAL 

为了修复它，请删除新创建的迁移。然后放下价格栏（价格保存为日期时间，如果有的话肯定不会有用）。然后执行./manage.py makemigrations，然后执行./manage.py迁移。

成功完成后，将价格字段添加回来，但是这次是以小数形式。