title: Import model from another app Django
body: <p>I have a problem importing a model from another app. I am using <code>Django 2.0</code>.</p>
  
  <p>My project structure looks like this:</p>
  
  <pre><code>--api
    --api
      --settings.py
      --urls.py
      --wsgi.py
    --product
      --models.py
    --chat
      --models.py
  --manage.py
  </code></pre>
  
  <p>To show only the problem I have I simplified the structure. If you are missing something important let me know it.</p>
  
  <p>The file causing the error:</p>
  
  <p><strong>chat/models.py</strong></p>
  
  <pre><code>from api.product.models import Product
  from django.contrib.auth.models import User
  from django.db import models
  
  
  class Chat(models.Model):
      product = models.ForeignKey(Product)
      enquirer = models.ForeignKey(User)
  </code></pre>
  
  <p><strong>product/models.py</strong></p>
  
  <pre><code>from django.db import models
  from django.contrib.auth.models import User
  
  class Product(models.Model):
      id = models.AutoField(primary_key=True)
      user = models.ForeignKey(User, on_delete=models.CASCADE)
      category = models.ForeignKey(Category, related_name='category', on_delete=None)
      front_image = models.ImageField(upload_to="")
      title = models.CharField(max_length=100)
      price = models.PositiveIntegerField()
      description = models.CharField(max_length=5000)
      date = models.DateTimeField(auto_now_add=True)
  </code></pre>
  
  <p><strong>settings.py</strong></p>
  
  <pre><code>INSTALLED_APPS = [
      'account.apps.AccountConfig',
      'product.apps.ProductConfig',
      'profileInfo.apps.ProfileInfoConfig',
      'chat.apps.ChatConfig',
      'django.contrib.admin',
      'django.contrib.auth',
      'django.contrib.contenttypes',
      'django.contrib.sessions',
      'django.contrib.messages',
      'django.contrib.staticfiles',
      'rest_framework',
      'rest_framework.authtoken',
      'corsheaders',
  ]
  </code></pre>
  
  <p>The error is the following: <code>ModuleNotFoundError: No module named 'api.product'</code> I do not understand why Django even can not find <code>api.product</code>. </p>
  
  <p>Is that a common problem ? Thank you for your help.</p>