Django：将默认值添加到ModelForms

Question

我正在研究django中的一个小项目，并且试图采用由用户填写并将其存储在数据库中的表单。对于表单，我正在使用ModelForm而不是标准Form。

用户使用表单创建的组的名称和说明提交表单。在将新对象添加到数据库之前，我想向模型中的表单值添加默认值。

这里是Form.py

from django import forms 
from django.forms import ModelForm 
from tab.models import Group 

member_count_choices = (('bronze', '1-4',), 
         ('silver', '5-7',), 
         ('gold', '8-10',), 
         ('platnium', '11+',)) 

class CreateGroupForm(forms.ModelForm): 
    class Meta: 
     model = Group 
     fields = ['name', 'description'] 

这里是views.py

from django.shortcuts import render, get_object_or_404, redirect 
from django.db import transaction 

from .models import Group, User 
from .forms import CreateGroupForm, AddMembersFour, AddMembersSeven 
from .forms import AddMembersTen, AddMembersEleven 

# the following def is going to be what grabs all of the different groups that 
# are in the database 
# filters can be added later 

def groups(request): 
    # following is all of th actions that are taken after the form is submitted 
    if request.method == 'POST': 
     createGroup = CreateGroupForm(request.POST) 
     if createGroup.is_valid(): 
      cd = createGroup.cleaned_data 
      groupName = cd['name'] 
      groupDescription = cd['description'] 
      groupDefaultLevel = 1 
      groupDefaultStatus = 1 
      groupDefaultCreatedBy = User.objects.get(username='omar') 
      new_group = createGroup 
      new_group.name = groupName 
      new_group.description = groupDescription 
      new_group.levels = groupDefaultLevel 
      new_group.status = groupDefaultStatus 
      new_group.created_by = groupDefaultCreatedBy 
      new_group.save() 
      return redirect('/tab/addMembers') 

这里是Models.py文件

from __future__ import unicode_literals 
from django.db import models 
from django.contrib.auth.models import User 

class Group(models.Model): 
    name = models.CharField(max_length = 25) 
    description = models.CharField(max_length = 250) 
    levels = models.SmallIntegerField() 
    status = models.SmallIntegerField() 
    created_by = models.ForeignKey(User, on_delete=models.CASCADE) 
    created = models.DateTimeField(auto_now_add=True) 

正如你所看到的。我正在尝试为组模型的级别，状态，created_by和create添加默认值。 created_by是我从管理网站创建的随机用户。

这里是什么地方的网站说：

IntegrityError at /tab/createGroup/ 
NOT NULL constraint failed: tab_group.levels 
Request Method: POST 
Request URL: http://127.0.0.1:8000/tab/createGroup/ 
Django Version: 1.8.6 
Exception Type: IntegrityError 
Exception Value:  
NOT NULL constraint failed: tab_group.levels 
Exception Location: C:\Users\OmarJandali\AppData\Local\Programs\Python\Python36\lib\site-packages\django\db\backends\sqlite3\base.py in execute, line 318 
Python Executable: C:\Users\OmarJandali\AppData\Local\Programs\Python\Python36\python.exe 
Python Version: 3.6.1 
Python Path:  
['C:\\Users\\OmarJandali\\Desktop\\opentab\\opentab', 
'C:\\Users\\OmarJandali\\AppData\\Local\\Programs\\Python\\Python36\\python36.zip', 
'C:\\Users\\OmarJandali\\AppData\\Local\\Programs\\Python\\Python36\\DLLs', 
'C:\\Users\\OmarJandali\\AppData\\Local\\Programs\\Python\\Python36\\lib', 
'C:\\Users\\OmarJandali\\AppData\\Local\\Programs\\Python\\Python36', 
'C:\\Users\\OmarJandali\\AppData\\Local\\Programs\\Python\\Python36\\lib\\site-packages'] 
Server time: Tue, 20 Jun 2017 23:03:09 +0000 

所以我只需要知道如何之前，它被保存到数据库中，以默认值添加到窗体。任何人都可以帮我

Answer 1

由于您使用的是模型表单，您可以设置字段模型的默认值。它看起来像这样：

class Group(models.Model): 
    name = models.CharField(max_length = 25) 
    description = models.CharField(max_length = 250, blank=True) 
    levels = models.SmallIntegerField(default=0) 
    status = models.SmallIntegerField(default=0) 
    created_by = models.ForeignKey(User, on_delete=models.CASCADE) 
    created = models.DateTimeField(auto_now_add=True