Python / Django makemigrations Error

Question

I have been messing around with Python and Django recently, following this tutorial - https://www.codementor.io/jadianes/get-started-with-django-building-recommendation-review-app-du107yb1a

I will be altering that app as I go, just to experiment, however I am at a bit of a standstill with 'makemigrations'.

When I run python manage.py makemigrations reviews I get a traceback as follows:

 Traceback (most recent call last):   File "manage.py", line 15, in
 <module>
     execute_from_command_line(sys.argv)   File "C:\Users\CalPC\AppData\Local\Programs\Python\Python36\lib\site-packages\django\core\management\__init__.py",
 line 371, in execute_from_command_line
     utility.execute()   File "C:\Users\CalPC\AppData\Local\Programs\Python\Python36\lib\site-packages\django\core\management\__init__.py",
 line 347, in execute
     django.setup()   File "C:\Users\CalPC\AppData\Local\Programs\Python\Python36\lib\site-packages\django\__init__.py",
 line 24, in setup
     apps.populate(settings.INSTALLED_APPS)   File "C:\Users\CalPC\AppData\Local\Programs\Python\Python36\lib\site-packages\django\apps\registry.py",
 line 112, in populate
     app_config.import_models()   File "C:\Users\CalPC\AppData\Local\Programs\Python\Python36\lib\site-packages\django\apps\config.py",
 line 198, in import_models
     self.models_module = import_module(models_module_name)   File "C:\Users\CalPC\AppData\Local\Programs\Python\Python36\lib\importlib\__init__.py",
 line 126, in import_module
     return _bootstrap._gcd_import(name[level:], package, level)   File "<frozen importlib._bootstrap>", line 994, in _gcd_import   File
 "<frozen importlib._bootstrap>", line 971, in _find_and_load   File
 "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked 
 File "<frozen importlib._bootstrap>", line 665, in _load_unlocked  
 File "<frozen importlib._bootstrap_external>", line 678, in
 exec_module   File "<frozen importlib._bootstrap>", line 219, in
 _call_with_frames_removed   File "C:\Users\CalPC\Desktop\review_app\prodreview\reviews\models.py", line
 2, in <module>
     import numpy as np ModuleNotFoundError: No module named 'numpy'

Here are my Models

from django.db import models
import numpy as np


class Product(models.Model):
    name = models.CharField(max_length=200)

    def average_rating(self):
        all_ratings = map(lambda x: x.rating, self.review_set.all())
        return np.mean(all_ratings)

    def __unicode__(self):
        return self.name

class Review(models.Model):
    RATING_CHOICES = (
        (1, '1'),
        (2, '2'),
        (3, '3'),
        (4, '4'),
        (5, '5'),
    )
    product = models.ForeignKey(Product)
    pub_date = models.DateTimeField('date published')
    user_name = models.CharField(max_length=100)
    comment = models.CharField(max_length=200)
    rating = models.IntegerField(choices=RATING_CHOICES)

I'm running Django 2.0 and python 3.6.5

If anyone could point out where I could be going wrong that would be great.

Thanks in advance!

line 2, in import numpy as np ModuleNotFoundError: No module named 'numpy' It seems like you forgot to install a dependency — Fernando Cezar
– Fernando Cezar, Commented Apr 27, 2018 at 14:06
when you activated your env hit pip install numpy and add it to your installed_apps in settings.py — hansTheFranz
– hansTheFranz, Commented Apr 27, 2018 at 14:08

Alasdair · Accepted Answer · 2018-04-27 14:27:45Z

3

You don't need numpy if you are only using it to calculate the mean. You could use statistics.mean instead.

import statistics

class Product(models.Model):
    name = models.CharField(max_length=200)

    def average_rating(self):
        all_ratings = map(lambda x: x.rating, self.review_set.all())
        return statistics.mean(all_ratings)

You can also use aggregate to get the database to calculate the average.

from django.db.models import Avg

def average_rating(self):
    return self.review_set.aggregate(avg_rating=Avg('rating'))['avg_rating']

Or annotate can be useful if you want to get the average for every product in the queryset.

Product.objects.annotate(avg_rating=Avg('review__rating'))

edited Apr 27, 2018 at 14:27

answered Apr 27, 2018 at 14:16

Alasdair

310k59 gold badges605 silver badges534 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Cal Over a year ago

Very helpful! Thank you.

Fernando Cezar · Accepted Answer · 2018-04-27 14:10:19Z

0

Make sure numpy is in your requirements file, and then pip install -r requirements.txt

answered Apr 27, 2018 at 14:10

Fernando Cezar

8487 silver badges22 bronze badges

Collectives™ on Stack Overflow

Python / Django makemigrations Error

2 Answers 2

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related