I'm new to Django, and I'm trying to create a "game" model with two attributes:
A many-to-one field where multiple instances of the game model are associated with an instance of a custom user model.
A many-to-many field where instances of the game model are connected with multiple instances of words, and instances of the word model are connected with multiple instances of the game model
Top of my models.py model:
from django.db import models
from users.models import CustomUser
from django.contrib.postgres.fields import ArrayField
Game model:
class SortingGame(models.Model):
user_current_player = models.ForeignKey(CustomUser, on_delete=models.CASCADE, null=True, blank=True)
field_words = models.ManyToManyField(Word, related_name="field_sorting_games")
Word model:
class Word(models.Model):
str_word = models.CharField(max_length=50,null=True)
int_grade_level = models.IntegerField()
arrint_phonemes = ArrayField(models.CharField(max_length=50),null=True)
arrstr_graphemes = ArrayField(models.CharField(max_length=50),null=True)
int_num_syllables = models.IntegerField()
arrstr_syllables = ArrayField(models.CharField(max_length=50),null=True)
User model:
class CustomUser(AbstractBaseUser):
# must have the following fields for django
email = models.EmailField(verbose_name="email",max_length = 100,unique=True)
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_superuser = models.BooleanField(default = False)
is_staff = models.BooleanField(default = False)
is_active = models.BooleanField(default = True)
first_name = models.CharField(max_length=15, blank=True)
last_name = models.CharField(max_length=30, blank=True)
spelling_level = models.IntegerField(default=1, unique=False)
time_played = models.IntegerField(default=0, unique=False)
percent_correct = models.IntegerField(default=0, unique=False)
admin.py:
from django.contrib import admin
from .models import Word, SortingGame
admin.site.register(SortingGame)
When I run python3 manage.py makemigrations and python3 manage.py migrate, it doesn't complain, but when I go to the admin page of my django site it says psycopg2.errors.UndefinedColumn: column "user_current_player_id" of relation "game_sortinggame" does not exist.
This makes me think the issue is with user_current_player in SortingGame (it worked fine before I added that attribute), but I've looked around on different forums to see what might be going wrong and I can't seem to figure it out. I tried starting from scratch with a new database, and it's still throwing the same exception. Any ideas would be appreciated—thanks!
Nathan!
First thing would be make sure that you have the app where CustomUser model is created in your settings.py file, at INSTALLED_APPS.
If so, please have a look at this folder (app) where you have CustomUser defined to verify if there is in deed a migrations folder there.
I suspect that Django in not aware of this app (not under INSTALLED_APPS) and therefore did not migrated it. So, your database is not finding the User Model connection.
That said, I would suggested you to keep your account model as defined by Django User and create another model with a direct relationship to it to deal with profile/game fields such as spelling level, percentage_correct and so on.
This would keep your Model "concerns" more organized later on.
if you did make a migrations before try to use (python manage.py makemigrations -appname)
Also after That you need to Add the module in your admin.py
from django.contrib import admin
from .models import *
admin.site.register(SortingGame)
... all other modules
Related
I tried to add a field to my ManyToMany relationship models in Django.
So step by step, I created the new model and apply makemigrations and migrate.
I checked I have the new table in my postgresql database.
Now before I will add the through keyword in the ManyToMany field I want to write a function in the migration file that will copy the old data of the previous ManyToMany table to the new one with the additional field.
I followed a solution explained here:
Django migration error :you cannot alter to or from M2M fields, or add or remove through= on M2M fields
I want to test the function that will migrate the data in a test function but I don't understand what to do.
here my code:
survey/models:
class Survey(BaseModel):
name = models.CharField(max_length=256, help_text='Survey name')
user = models.ManyToManyField(User, blank=True, help_text='patient')
survey/models:
class SurveyStatus(models.Model):
user = models.ForeignKey(User, on_delete=models.CASCADE)
survey = models.ForeignKey(Survey, on_delete=models.CASCADE)
survey_status = models.CharField(max_length=10,
blank=True,
null=True,
choices=STATUS_SURVEY_CHOICES,
)
The function I wrote that need to copy the data from the previous M2M to the new one is the following one:
def create_through_relations(apps, schema_editor):
Survey = apps.get_model('survey', 'Survey')
SurveyStatus = apps.get_model('survey', 'SurveyStatus')
for survey in Survey.objects.all():
for user in survey.user.all():
SurveyStatus(
user=user,
survey=survey,
survey_status='active'
).save()
I don't understand what is apps? because it is not recognized by python
I don't understand why i need schema_editor because it's not used
it doesn't recognized my Survey or SurveyStatus models too
when i tried to run this script with
if __name__ == "__main__":
create_through_relations(survey)
I've got this error
NameError: name 'survey' is not defined
and if i tried this function
from django.apps import apps
def create_through_relations():
Survey = apps.get_model('survey', 'Survey')
SurveyStatus = apps.get_model('survey', 'SurveyStatus')
for survey in Survey.objects.all():
for user in survey.user.all():
SurveyStatus(
user=user,
survey=survey,
survey_status='active'
).save()
when i tried to run this script with
if __name__ == "__main__":
create_through_relations()
I've got this error
django.core.exceptions.AppRegistryNotReady: Models aren't loaded yet.
If someone can help and explain me how to solve.thanks
1: Apps represent the different parts of your project (Django Apps)
2: You don't need it at this point. In general, it translates the models into SQL syntax.
3: python manage.py <...> does load the models for execution. Your file is trying to access data that isn't available that way.
4: The variable survey can't be found in python's main function, since you never declared it there. You need to trigger it inside your project.
5: You can test things by creating a test.py (Django Tests)
6: You don't need to transfer the data to a whole new table after changing a model, just extend the existing one and migrate the changes:
class BaseModel(models.Model):
created = models.DateTimeField('created', default=timezone.now)
changed = models.DateTimeField('changed', default=timezone.now, blank=True, null=True)
class Survey(BaseModel):
uuid = models.UUIDField(primary_key=False, default=uuid.uuid4, editable=False)
name = models.CharField(max_length=256, help_text='Survey name')
description = models.TextField('description', blank=True)
status = models.BooleanField(default=False) # paused/ active
class SurveyQuestion(BaseModel):
survey = models.ForeignKey(Survey, related_name='survey', on_delete=models.CASCADE)
text = models.CharField(max_length=256)
# 1 -> Text, # Integer, # ChoiceField, etc.
requested_result = models.IntegerField(default=0)
class QuestionResult(BaseModel):
user = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
question = models.ForeignKey(SurveyQuestion, related_name='survey_question', on_delete=models.CASCADE)
answer = models.CharField(default='', max_length=256)
I would like to execute a single query in Django which retrieves related data, by foreign key, in multiple tables. At present I have to run a query on each table e.g. (House, Furniture, People) using the House number as a filter.
In SQL I can do this in one query like this:
SELECT house.number, house.number_of_rooms, furniture.type, people.name
FROM (house INNER JOIN furniture ON house.number = furniture.house_number)
INNER JOIN people ON house.number = people.house_number
WHERE (((house.number)="21"));
Can this be done in Django?
See example models below:
class House(models.Model):
number = models.CharField('House Number', max_length=10, blank=True, unique=True, primary_key=True)
number_of_rooms = models.IntegerField(default=1, null=True)
class Furniture(models.Model):
house_number = models.ForeignKey(House, on_delete=models.CASCADE, null=True)
type = models.CharField('Furniture Type', max_length=50)
class People(models.Model):
house_number = models.ForeignKey(House, on_delete=models.CASCADE, null=True)
first_name = models.CharField('First Name', max_length=50)
In your models add related_name arguments for foreign keys, so that you can retrieve the objects related to the House() instance.
class Furniture(models.Model):
house_number = models.ForeignKey(House, related_name='house_furniture', on_delete=models.CASCADE, null=True)
type = models.CharField('Furniture Type', max_length=50)
class People(models.Model):
house_number = models.ForeignKey(House, related_name='house_people', on_delete=models.CASCADE, null=True)
first_name = models.CharField('First Name', max_length=50)
Then run the migration using following commands.
python manage.py makemigrations
python manage.py migrate
Then create a new serializers.py module in the same app.
#import models Furniture, People, house
from rest_framework import serializers
class FurnitureSerializer(serializer.ModelSerializer):
class Meta:
model = Furniture
fields = ['type'] # if you want all the fields of model than user '__all__'.
class PeopleSerializer(serializer.ModelSerializer):
class Meta:
model = People
fields = ['first_name'] # if you want all the fields of model than user '__all__'.
class HouseSerializer(serializer.ModelSerializer):
house_furniture = FurnitureSerializer(many=True)
house_people = PeopleSerializer(many=True)
class Meta:
model = Furniture
fields = ['number', 'number_of_rooms', 'house_furniture', 'house_people']
Now, in your views.py you can simply query on model House and serializer the result with HouseSerializer().
#import models from models.py
#import serializer from serializers.py
from rest_framework.views import APIView
from rest_framework.response import Response
from rest_framework import status
from rest_framework.generics import ListAPIView
class ListHouseView(ListAPIView):
serializer_class = HouseSerializer
queryset = House.objects.filter() #here you can apply filters on the fields of house model and user using related_name you can filter on other related models as well.
Now, simply call ad this in your app's urls.py
url_pattern = [
path('list-house/', ListHouseView.as_view()),
]
Make sure that have a path in your project's urls.py to reach this app's urls.py.
The usual Django way of dealing with this is Queryset.prefetch_related() and iterating through Python (unless you're using Postgres, which has its own solution of ArrayAgg). Given your models, it'll cost three queries, but you won't have to deal with de-normalized row results.
h = House.objects.prefetch_related('furniture_set', 'people_set').get(number='21')
for furniture in house.furniture_set.all():
print(furniture)
for person in house.people_set.all():
print(people)
prefetch_related() caches the results and does the "joining" in Python once the queryset is evaluated, so iterating through the reverse relationships won't incur additional queries, and you're free to structure/serialize the data however you like. The raw SQL from this is something like:
SELECT house.number, house.number_of_rooms FROM house WHERE house.number = '1'
SELECT furniture.id, furniture.house_number_id, furniture.type FROM furniture WHERE furniture.house_number_id IN ('1')
SELECT people.id, people.house_number_id, people.first_name FROM people WHERE people.house_number_id IN ('1')
But Django does that behind-the-scenes so that you can just deal with a model instance in Python.
I'm currently trying to setup some database models in djangos ORM. however im unable to figure out how i'm supposed to reference another models many-to-many- field.
Project model
class Project(models.Model):
projectName = models.CharField(max_length=200)
users = models.ManyToManyField(get_user_model())
projectOwner = models.ForeignKey(get_user_model(), on_delete=models.CASCADE, related_name='projectowner', default=1)
The users = models.manytomanyfield(get_user_mode()) works fine
and generates the correct relation in the database.
now i want to add a new model that adds a many to many relation between rights and project_user
so what the end result tables are supposed to look like:
project:
projectname - string
projectowner - id of referenced user
user: django orm auth user model
rights:
name
description
etc
project_user:
id
project_id
user_id
rights_projectuser:
id
rights_id
project_user_id
now that last one (rights_projectuser) is what i dont know how to make.
You need to turn "project_user" into a through model that you can then add the many to many relationship to.
class Project(models.Model):
projectName = models.CharField(max_length=200)
users = models.ManyToManyField(get_user_model(), through='ProjectUser')
class ProjectUser(models.Model):
project = models.ForeignKey(Project, on_delete=models.CASCADE)
user = models.ForeignKey(get_user_model(), on_delete=models.CASCADE)
rights = models.ManyToManyField(Right)
i now get the following problem when running this code:
from django.db import models
from django.contrib.auth import get_user_model
User = get_user_model()
class Project(models.Model):
projectName = models.CharField(max_length=200)
users = models.ManyToManyField(get_user_model(), through='ProjectUser')
projectOwner = models.ForeignKey(get_user_model(), on_delete=models.CASCADE, related_name='projectowner', default=1)
class Right(models.Model):
name = models.CharField(max_length=200)
description = models.CharField(max_length=1000)
class ProjectUser(models.Model):
user_id = models.ForeignKey(get_user_model(), on_delete=models.CASCADE)
project_id = models.ForeignKey(Project, on_delete=models.CASCADE)
rights = models.ManyToManyField(Right)
ValueError: Cannot alter field wspingpong.Project.users into wspingpong.Project.users - they are not compatible types (you cannot alter to or from M2M fields, or add or remove through= on M2M fields)
I need to add job offers section to my company site (as a intro to django for me). The problem is that when i inherit my model from mezzanine's Page model it adds to admins create form all bunch of field which i dont need (like publish dates, draft field, comment field etc). I want to make create/edit job offers form as simple as possible.
I tried to inherit it from basic models.Model but it throws an error ...
Unknown column 'project_joboffer.id' in 'field list'"
I tried to customize Admin Form but im still getting error above.
models.py
class JobOffer(models.Model):
title = models.CharField(max_length=255, null=False, blank=False)
place = models.CharField(max_length=255, null=True, blank=True)
date = models.DateTimeField(auto_now_add=True)
content = models.TextField(blank=False,null=False)
published = models.BooleanField(default=True)
deleted = models.NullBooleanField()
forms.py
from django import forms
from ckeditor.widgets import CKEditorWidget
from models import JobOffer
class JobOfferForm(forms.ModelForm):
title = forms.CharField(max_length=255, required=True)
place = forms.CharField(max_length=255, required=False)
content = forms.CharField(required=True , widget=CKEditorWidget())
published = forms.BooleanField(initial=True)
deleted = forms.NullBooleanField()
# class Meta:
# model = JobOffer
admin.py
class JobOfferAdmin(admin.ModelAdmin):
form = JobOfferForm
admin.site.register(JobOffer, JobOfferAdmin)
OK, i fixed it. Migrations creating and deleting wasnt enough. I dont know why but this time i had to also delete entry in django_migrations table.
I'm using Django 1.5 on Python 3.2.3.
When I run python3 manage.py syncdb, it builds the DB tables, & asks for my email (defined as the unique instead of a username), and then when I enter that, I get this error --
AttributeError: 'Manager' object has no attribute 'get_by_natural_key'
Oddly, it creates the tables anyway, but now, I'm confused 'cause I really don't get what I'm supposed to do. The documentation says I should create a Custom User Manager, but that's all it really says. It doesn't give me a clue where to create it or how. I looked through the docs on Managers, but that really didn't help me figure anything out. It's all too vague. I keep Googling trying to find some clue as to what I need to do, but I'm just going crazy with more and more questions instead of any answer. Here's my models.py file:
from django.db import models
from django.contrib.auth.models import AbstractBaseUser
class MyUsr(AbstractBaseUser):
email = models.EmailField(unique=True,db_index=True)
fname = models.CharField(max_length=255,blank=True, null=True)
surname = models.CharField(max_length=255,blank=True, null=True)
pwd_try_count = models.PositiveSmallIntegerField(blank=True, null=True)
pwd_last_try = models.DateTimeField(blank=True, null=True)
resetid = models.CharField(max_length=100,blank=True, null=True)
last_reset = models.DateTimeField(blank=True, null=True)
activation_code = models.CharField(max_length=100,blank=True, null=True)
USERNAME_FIELD = 'email'
REQUIRED_FIELDS = ['fname','activation_code']
How do I write a Custom User Manager? Do I put it in the MyUsr model as a method? Or is that even what I'm supposed to do? Should I be doing something totally different? I'm not sure of anything at this point. I just don't understand. The documentation on this doesn't seem clear to me, leaving a lot open for interpretation. I'm pretty new to Django, but I've been into Python for several months.
You define a custom manager by sub-classing BaseUserManager and assigning it in your Model to the objects attribute.
from django.contrib.auth.models import AbstractUser, BaseUserManager
class MyMgr(BaseUserManager):
def create_user(...):
...
def create_superuser(...):
...
class MyUsr(AbstractBaseUser):
objects = MyMgr()
email = models.EmailField(unique=True, db_index=True)
fname = models.CharField(max_length=255, blank=True, null=True)
...
You must define the create_user and create_superuser methods for your BaseUserManager. See the docs.
Depending on your case all you might need to fix this error will be to assign the objects variable in the CustomUser class, to inherit form BaseUserManager() instead of models.Manager() which some would have initially set
from django.db import models
from django.contrib.auth.models import AbstractUser, BaseUserManager
class CustomUser(AbstractUser):
name = models.CharField(null=True, blank=True, max_length=100)
......
# model managers
# objects = models.Manager()
objects = BaseUserManager()