Django通过电子邮件向ManyToMany关系中的用户发送电子邮件

Question

我想在创建新帖子时将通知电子邮件发送到“观察者”ManyToMany字段中定义的用户列表。

创建的帖子没有错误，并且观察者用户列表已成功添加（它们显示在post_detail.html模板中），但通知电子邮件永远不会发送给观察者用户。

我认为我在下面的new_post函数中做错了，我在this code改编后用于在用户对帖子发表评论时发送电子邮件。任何帮助非常感谢。

models.py（相关部分）：

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

from django.contrib.sites.models import Site
from django.db.models import signals
from notification import models as notification

class Post(models.Model):
    author = models.ForeignKey(User, related_name="added_posts")
    observers = models.ManyToManyField(User, verbose_name=_("Observers"), related_name='observers+', blank=True, null=True)

# send notification to Post observers
def create_notice_types(app, created_models, verbosity, **kwargs):
    notification.create_notice_type("new_post", "New post created", "A new post has been created")
signals.post_syncdb.connect(create_notice_types, sender=notification)

def new_post(sender, instance, created, **kwargs):   

    context = {
        'observer': instance,
        'site': Site.objects.get_current(),
    }

    recipients = []
    pk=instance._get_pk_val()

    for observer in instance.observers.all().distinct():
        if observer.user not in recipients:
            recipients.append(observer.user)

    notification.send(recipients, 'new_post', context)

signals.post_save.connect(
    new_post, sender=models.get_model(
    'blog', 'Post'), dispatch_uid="pkobservers")

views.py（相关部分）：

@login_required
def add(request, form_class=PostForm, template_name="blog/post_add.html"):
    post_form = form_class(request)
    if request.method == "POST" and post_form.is_valid():
        post = post_form.save(commit=False)
        post.author = request.user
        post_form.save()
        post_form.save_m2m()
        return redirect("blog_user_post_detail", 
            username=request.user.username, slug=post.slug)
    return render_to_response(template_name, 
        {"post_form": post_form}, context_instance=RequestContext(request))

编辑：

还试过这个（删除blog_post和blog_post_observers表，然后再次运行manage.py syncdb，但仍然无效）：

models.py

class Post(models.Model):
    # ....
    observers = models.ManyToManyField(User, verbose_name=_("Observers"), related_name='observers+')

def new_post(sender, instance, created, **kwargs):   

    context = {
        'observer': instance,
        'site': Site.objects.get_current(),
    }

    recipients = instance.observers.all()
    pk=instance._get_pk_val()

    notification.send(recipients, 'new_post', context)

signals.post_save.connect(new_post, sender=models.get_model('blog', 'Post'), dispatch_uid="pkobservers")

编辑2 2013年6月27日星期四：11：48：49意大利时间：

当我编辑/更新帖子时，使用以下视图，通知电子邮件可以正常工作：

views.py

@login_required
def edit(request, id, form_class=PostForm, template_name="blog/post_edit.html"):
    post = get_object_or_404(Post, id=id)
    if post.author != request.user:
        request.user.message_set.create(message="You can't edit items that aren't yours")
        return redirect("desk")
    post_form = form_class(request, instance=post)
    if request.method == "POST" and post_form.is_valid():
        post = post_form.save(commit=False)
        post.updated_at = datetime.now()
        post_form.save()
        post_form.save_m2m()
        messages.add_message(request, messages.SUCCESS, message=_("Successfully updated post '%s'") % post.title)
        return redirect("blog_user_post_detail", username=request.user.username, slug=post.slug)
    return render_to_response(template_name, {"post_form": post_form, "post": post}, context_instance=RequestContext(request))

Answer 1

首先，我认为您的多对多关系不应该为空或空，因为每个观察者理想情况下都是用户而不是无。这样可以避免尝试向无用户发送电子邮件，这可能会导致错误。

其次，我认为你可以使用

recipients = instance.observers.all().distinct()

而不是在列表上循环（distinct（）已经只考虑了唯一用户）

第三，我不明白为什么你真的需要一个“distinct（）”：用户能不止一次成为观察者吗？

recipients = instance.observers.all()

第四，在你的代码中，你通过一个“观察者”（已经是一个用户）循环使用instance.observers.all（）。为什么要将observer.user附加到收件人？我认为附加观察者就足够了。

最后，确认收件人不是空的。如果您已经测试了notification.send（），那么您的代码似乎是正确的。

Answer 2

想出来 - 通知电子邮件现在在创建新帖子时发送给观察者。

基本上我在设置post.id后需要call save a second time：

views.py：

@login_required
def add(request, form_class=PostForm, template_name="blog/post_add.html"):
    post_form = form_class(request)
    if request.method == "POST" and post_form.is_valid():
        post = post_form.save(commit=False)
        post.author = request.user
        post_form.save()
        post.id = post.id # set post id
        post_form.save() # save a second time for notifications to be sent to observers 
        return redirect("blog_user_post_detail", 
            username=request.user.username, slug=post.slug)
    return render_to_response(template_name, 
        {"post_form": post_form}, context_instance=RequestContext(request))

models.py与第一次编辑没有变化：在问题中（感谢J. C. Leitão的帮助）。

这是确定的：

models.py

class Post(models.Model):
    observers = models.ManyToManyField(User, verbose_name=_("Observers"), related_name='observers+')

def new_post(sender, instance, created, **kwargs):   

    context = {
        'observer': instance,
        'site': Site.objects.get_current(),
    }

    recipients = instance.observers.all()
    pk=instance._get_pk_val()

    notification.send(recipients, 'new_post', context)

signals.post_save.connect(new_post, sender=models.get_model('blog', 'Post'), dispatch_uid="pkobservers")