如何在Django中为模型设置默认值？

Question

我想创建一个邀请应用程序，其中包含发件人，收件人和邮件。 如何将当前登录的用户设置为不可变的发件人？

在model.py

中

class Invitation(models.Model):
    from_user = models.CharField(max_length=100)
    to_user = models.ForeignKey(User, related_name="invitations_received")
    message = models.CharField(max_length=300)
    timestap = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return "{} to {}: {}".format(self.from_user, self.to_user, self.message)

在views.py

中

from django.shortcuts import render, redirect
from django.contrib.auth.decorators import login_required
from .models import Game
from .models import Invitation
from .forms import InvitationForm

@login_required

def new_invitation(request):
    if request.method == 'POST':
        form = InvitationForm(data=request.POST, from_user=request.user)
        if form.is_valid():
            form.save()
            return redirect('profiles_home')
    else:
        form = InvitationForm()
    return render(request, "arosis/new_invitation.html", {'form': form})

在forms.py

中

from django.forms import ModelForm
from .models import Invitation
from django.shortcuts import render




class InvitationForm(ModelForm):
    class Meta:
        model = Invitation

Answer 1

您不能简单地默认为当前用户，因为Django ORM通常不知道Django身份验证系统。你应该：

1）在创建模型实例时传递request.user，如：

invitation = Invitation(from_user=request.user)

或

2）使用中间件，每次保存时将当前用户添加到模型中。您可以尝试以下其中一个包：https://www.djangopackages.com/grids/g/model-audit/

Answer 2

我为自己轻松解决了以下问题：

在models.py中：

class Invitation(models.Model):
    from_user = models.ForeignKey(User, related_name="invitations_sent")
    to_user = models.ForeignKey(User, related_name="invitations_received",
                                verbose_name="User to invite",
                                help_text="Please Select the user you want.")
    message = models.CharField("Optional Message", max_length=300, blank=True,
                               help_text="Adding Friendly Message")
    timestap = models.DateTimeField(auto_now_add=True)
    def __str__(self):
        return "{} to {}: {}".format(self.from_user, self.to_user, self.message)

在views.py中：

def new_invitation(request):
    if request.method == 'POST':
        invitation = Invitation(from_user=request.user)
        form = InvitationForm(data=request.POST, instance=invitation)
        if form.is_valid():
            form.save()
            return redirect('arosis_invite')
    else:
        form = InvitationForm(data=request.POST)
    return render(request, "arosis/new_invitation.html", {'form': form})

在forms.py中：

class InvitationForm(ModelForm):
    class Meta:
        model = Invitation
        exclude = ['from_user']

在模板文件中：

我解决它真的很容易！使用：

{{ user.username }}