更正 django 模板的 if/else 语句语法

Question

我有一个约会应用程序，我需要在用户匹配的每个个人资料下方创建一个链接。然后，该链接应该将他们的用户 ID 传递到模板中，以便仅在当前用户和基于用户 ID 的特定用户之间显示消息。我在这里遇到了 Django 模板中 if/else 语句的语法问题。我该怎么做呢？

**base.html/href 消息链接**

<li class="nav-item">
                    <a class="nav-link" href="{% url 'dating_app:messages' user.id %}">Check Messages</a>
                </li>

models.py/InstantMessage

class InstantMessage(models.Model):

    sender = models.ForeignKey(settings.AUTH_USER_MODEL, related_name= 'sender',on_delete=models.CASCADE )
    receiver = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
    message = models.TextField()
    date = models.DateTimeField(auto_now_add=True)


    def __unicode__(self):
        return self.message

messages.html

<div id="msg-list-div" class="panel-body">
        <ul id="msg-list" class="list-group">
            <br><br><br>
            {% for obj in messages %}
                {% if obj.sender == request.user and obj.receiver == profile%}

                    {% if obj.sender == request.user%}
                        <li class="text-right list-group-item">{{obj.message}}<br>{{ obj.date }}<li>
                    {% elif obj.receiver == profile %}
                        <li class="text-left list-group-item">{{obj.message}}<br>{{ obj.date }}<li>
                    {%endif%} 

                {%endif%}   
                {% empty %}
                    <li class="text-right list-group-item">No messages yet...Keep mingling!</li>
            {% endfor %}

        </ul>
</div>

ma​​tches.html/messages.html 的 href 链接

<p><a href="{% url 'dating_app:messages' profile.id %}">chat</a></p>

views.py/messages

def messages(request, profile_id):
    messages = InstantMessage.objects.all()
    profile = get_object_or_404(Profile,id=profile_id)

    return render(request, 'dating_app/messages.html', {'messages': messages,'profile':profile,})

models.py

class Profile(AbstractBaseUser):

    class Meta:
        swappable = 'AUTH_USER_MODEL'


    email                       = models.EmailField(verbose_name="email")
    username                    = models.CharField(max_length=30, unique=True)
    date_joined                 = models.DateTimeField(verbose_name='date joined', auto_now_add=True)
    last_login                  = models.DateTimeField(verbose_name='last login', auto_now=True)
    is_admin                    = models.BooleanField(default=False)
    is_active                   = models.BooleanField(default=True)
    is_staff                    = models.BooleanField(default=False)
    is_superuser                = models.BooleanField(default=False)
    #what I added
    description                 = models.TextField()
    photo                       = models.ImageField(upload_to='profile_photo',blank=False, height_field=None, width_field=None, max_length=100)
    matches                     = models.ManyToManyField(settings.AUTH_USER_MODEL, related_name='+', blank=True)

    USERNAME_FIELD = 'username'
    REQUIRED_FIELDS = ['description','photo','email']

    objects = ProfileManager()

    def __str__(self):
        return self.username

    def has_perm(self, perm, obj=None):
        return self.is_admin

    def has_module_perms(self,app_label):
        return True


class UserVote(models.Model):

    user = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
    voter = models.ForeignKey(settings.AUTH_USER_MODEL, related_name='given_vote', on_delete=models.CASCADE)
    vote = models.BooleanField(default=False)

    class Meta:
        unique_together = (('user', 'voter'))


class InstantMessage(models.Model):

    sender = models.ForeignKey(settings.AUTH_USER_MODEL, related_name= 'sender',on_delete=models.CASCADE )
    receiver = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
    message = models.TextField()
    date = models.DateTimeField(auto_now_add=True)


    def __unicode__(self):
        return self.message

整个models.py

from django.db import models
from django.contrib.auth.models import AbstractBaseUser,BaseUserManager, User
from dating_project import settings
from django.contrib.auth import get_user_model


class ProfileManager(BaseUserManager):



    def create_user(self, username, email,description,photo, password=None):
        if not email:
            raise ValueError("You must creat an email")
        if not username:
            raise ValueError("You must create a username!")
        if not description:
            raise ValueError("You must write a description")
        if not photo:
            raise ValueError("You must upload a photo")

        user = self.model(
                email=self.normalize_email(email),
                username = username, 
                description= description,
                photo= photo,

            )

        user.set_password(password)
        user.save(using=self._db)
        return user 


    def create_superuser(self, username, email,description,photo, password):
        user = self.create_user(
                email=self.normalize_email(email),
                password=password,
                username=username,
                description=description,
                photo=photo,

            )

        user.is_admin=True
        user.is_staff=True
        user.is_superuser=True
        user.save(using=self._db)
        return user




class Profile(AbstractBaseUser):

    class Meta:
        swappable = 'AUTH_USER_MODEL'


    email                       = models.EmailField(verbose_name="email")
    username                    = models.CharField(max_length=30, unique=True)
    date_joined                 = models.DateTimeField(verbose_name='date joined', auto_now_add=True)
    last_login                  = models.DateTimeField(verbose_name='last login', auto_now=True)
    is_admin                    = models.BooleanField(default=False)
    is_active                   = models.BooleanField(default=True)
    is_staff                    = models.BooleanField(default=False)
    is_superuser                = models.BooleanField(default=False)
    #what I added
    description                 = models.TextField()
    photo                       = models.ImageField(upload_to='profile_photo',blank=False, height_field=None, width_field=None, max_length=100)
    matches                     = models.ManyToManyField(settings.AUTH_USER_MODEL, related_name='+', blank=True)



    USERNAME_FIELD = 'username'
    REQUIRED_FIELDS = ['description','photo','email']


    objects = ProfileManager()


    def __str__(self):
        return self.username


    def has_perm(self, perm, obj=None):
        return self.is_admin


    def has_module_perms(self,app_label):
        return True



class UserVote(models.Model):

    user = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
    voter = models.ForeignKey(settings.AUTH_USER_MODEL, related_name='given_vote', on_delete=models.CASCADE)
    vote = models.BooleanField(default=False)

    class Meta:
        unique_together = (('user', 'voter'))



class InstantMessage(models.Model):

    sender = models.ForeignKey(settings.AUTH_USER_MODEL, related_name= 'senderr',on_delete=models.CASCADE )
    receiver = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
    message = models.TextField()
    date = models.DateTimeField(auto_now_add=True)


    def __unicode__(self):
        return self.message

Answer 1

正如已经建议的那样，最好在视图中完成所有繁重的工作，而不是在模板中：

def messages(request, profile_id):
    messages = InstantMessage.objects.filter(sender=request.user, receiver_id=profile_id, )
    profile = get_object_or_404(Profile,id=profile_id)
    ...

想象一下，如果 InstantMessage 包含数十亿条记录 - InstantMessage.objects.all() 的工作速度有多快？以及出于什么原因。

既然你想渲染“聊天”，我猜你需要这样的东西：

from django.db.models import Q
...
    messages = InstantMessage.objects.filter(Q(sender_id=request.user.id, receiver_id=profile_id,) 
            | Q(sender_id=profile_id, receiver_id=request.user.id,) ).\
        values('sender_id', 'message', 'date', ).\
        order_by('date',)

另请参阅the docs 中进行复杂查询的示例。

和模板：

{% for msg in messages %}
    <li class="{% if msg.sender_id == request.user.id %}text-right{% else %}text-left{% endif %} list-group-item">
        {{ msg.message }}<br/>{{ msg.date }}
    </li>
{% empty %}
    ...
{% endfor %}