I'm trying out a new django social media project which has User, Status and Comment. The relationship between them is such that, User has a relationship to Status, User has relationship to Comment and there also exists a relationship between Status and comment.
So to achieve this I built four tables, i.e, User, Comment, Status and UCSModel. Where UCSModel is the table which has the foreign keys of the rest three tables. UCSModel is more like the relations table consisting of all ID's
So here is my models.py
from django.db import models
class User(models.Model):
username = models.CharField(max_length=50, unique=True)
email = models.CharField(max_length=200)
password = models.CharField()
def __str__(self):
return self.username
class Comment(models.Model):
comment = models.CharField()
def __str__(self):
return self.comment
class Status(models.Model):
status = models.CharField()
def __str__(self):
return self.status
class USCRelation(models.Model):
user = models.ForeignKey(User, null=True, on_delete=models.CASCADE)
comment = models.ForeignKey(Comment, null=True, on_delete=models.CASCADE)
status = models.ForeignKey(Status, null=True, on_delete=models.CASCADE)
Being new to Django, I wanted to know if there is any better way of building relationships between tables. Especially when all the three tables are interrelated to each other like in my case above.
Find the below DB design, this would help you optimising your queries:
from django.db import models
class User(models.Model):
username = models.CharField(max_length=50, unique=True)
email = models.CharField(max_length=200)
password = models.CharField()
def __str__(self):
return self.username
class Status(models.Model):
status = models.CharField()
def __str__(self):
return self.status
class Comment(models.Model):
comment = models.CharField()
status = models.ForeignKey(Status, on_delete=models.CASCADE)
user = models.ForeignKey(User, on_delete=models.CASCADE)
def __str__(self):
return self.comment
Hope this helps!
Related
In DRF I am facing an issue, whenever I do a POST request on the endpoint, on the field "name" which is a text field I get an exception "Field 'id' expected a number but got 'TITLE'", but when I change the value of "name" to an integer the request is successful I don't understand it becauses name is TextField in model and why its mixing Id and Name field with each other. I have deleted the migration files from the Project and DB and re-run the Migrations, but still facing this issue.
Following is my code:
models.py
class Project(models.Model):
admin = models.ForeignKey(User, on_delete=models.CASCADE, related_name='project_crated_by')
name = models.TextField(max_length=225, blank=False, null=False)
project_members = models.ForeignKey(User, on_delete=models.CASCADE, verbose_name='members', null=True, blank=True)
created_on = models.DateField(default=timezone.now)
tags = ArrayField(models.CharField(max_length=225, default=''), blank=True)
def __str__(self):
return self.name
objects = models.Manager()
views.py
class ProjectView(viewsets.ViewSet):
def create(self, request):
project_name_exist = Project.verify_project_name(request.data['admin'], request.data['name'])
if project_name_exist:
return Response({'message': 'You already have a project with this name',
'status': status.HTTP_200_OK})
serialized_project = ProjectSerializer(data=request.data)
if serialized_project.is_valid():
serialized_project.save()
return Response({'message': 'Project Created Successfully', 'status': status.HTTP_201_CREATED})
else:
return Response({'error': serialized_project.errors, 'status': status.HTTP_400_BAD_REQUEST})
serializer.py
class ProjectSerializer(serializers.ModelSerializer):
class Meta:
model = Project
fields = '__all__'
A more generic and non-DIY solution is to use UniqueTogetherValidator on your serializer and let Django sort it out.
from rest_framework.validators import UniqueTogetherValidator
class ProjectSerializer(serializers.ModelSerializer):
class Meta:
model = Project
fields = '__all__'
validators = [
UniqueTogetherValidator(
queryset=Project.objects.all(),
fields=['admin', 'name'],
message='You already have a project with this name'
)
]
And/or add it to the model for enforcing it on the database.
class Project(models.Model):
admin = models.ForeignKey(User, on_delete=models.CASCADE, related_name='project_crated_by')
name = models.TextField(max_length=225, blank=False, null=False)
project_members = models.ForeignKey(User, on_delete=models.CASCADE, verbose_name='members', null=True, blank=True)
created_on = models.DateField(default=timezone.now)
tags = ArrayField(models.CharField(max_length=225, default=''), blank=True)
def __str__(self):
return self.name
objects = models.Manager()
class Meta:
unique_together = ("admin", "name")
I am working on a small application containing models CustomUser and PollQuestion. CustomUser having ManyToMany relation between itself and a CustomUser can have multiple PollsQuestion as well so there is Foreign Key relation between them.
An authenticated user is only able to see polls raised by users he is following, to full-fill this requirement i have written following view**:-**
Actually this is not view this is an utility method returning the polls to original view.
def all_polls_utils(request):
following = request.user.get_all_followings().values_list("id")
user_id = [id[0] for id in following]
all_polls = PollQuestion.objects.none()
for u_id in user_id:
user = CustomUser.objects.get(id=u_id)
polls = user.poll_questions.all()
all_polls = all_polls | polls
return all_polls
Main Question:- Is there in better way to do the same?
Any suggestion will be highly appretiated
I am posting the models bellow:-
from django.db import models
from django.contrib.auth.models import AbstractUser
# Create your models here.
class CustomUser(AbstractUser):
email = models.EmailField(max_length=250, null=False)
name = models.CharField(max_length=50, null=False)
username = models.CharField(max_length=50, null=False, unique=True)
password = models.CharField(max_length=15, null=False)
user = models.ManyToManyField('self', through='Relationship', symmetrical=False, related_name='related_to')
USERNAME_FIELD = 'username'
REQUIRED_FIELDS = ['name', 'email']
def get_all_polls(self):
pass
def create_relationship(self, person):
status, obj = Relationship.objects.get_or_create(
to_person=person,
from_person=self,
)
return status
def remove_relationship(self, person):
Relationship.objects.filter(
from_person=self,
to_person=person
).delete()
return 'dummy_value'
def get_all_followings(self):
return self.user.all()
class Relationship(models.Model):
from_person = models.ForeignKey(CustomUser, related_name='from_people', on_delete=models.CASCADE)
to_person = models.ForeignKey(CustomUser, related_name='to_person', on_delete=models.CASCADE)
And PollQuestion:-
class PollQuestion(models.Model):
user = models.ForeignKey(CustomUser, null=True, on_delete=models.CASCADE, related_name="poll_questions")
# Other fields
Note:- You can also suggest me a better title for this post?
Thanks in advance,
Hope to here from you soon.
Simply
def all_polls_utils(request):
all_polls_by_followed = PollQuestion.objects.filter(
user__in=request.user.get_all_followings()
)
As an aside, you should probably rename the user many-to-many in CustomUser to e.g. followed_users (with a related name followers).
I have some models:
from django.db import models
from django.conf import settings
class Question(models.Model):
name = models.CharField(unique=True, max_length=50)
desctiption = models.TextField(max_length=500, unique=True)
def __repr__(self):
return f"Question: {self.name}"
class Answer(models.Model):
"""Answer for one question. Can be correct or incorrect"""
name = models.CharField(unique=True, max_length=50)
question = models.ForeignKey(Question, on_delete=models.CASCADE)
answer = models.CharField(max_length=50)
is_correct = models.BooleanField(default=False)
def __repr__(self):
return f"Answer: {self.name}"
class Quiz(models.Model):
"""Quiz Model contain questions"""
name = models.CharField(unique=True, max_length=50)
desctiption = models.TextField(max_length=500, unique=True)
questions = models.ManyToManyField(Question)
def __repr__(self):
return f"Quiz: {self.name}"
class ProgressUserQuiz(models.Model):
"""Save user progress for any quiz"""
...
I can't understand how to structure ProgressUserQuiz.
For example. If user passed two questions in quiz and close a tab he can return to his last questions. And When he finished I want to add this in model.
How can I make it?tnx
You can use a Status flag for the questions
class ProgressUserQuiz(models.Model):
status_opt = (
('answered',"Answered"),
('passed',"Passed"),
('closed',"Closed"),
)
user = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
question = models.ForeignKey(Question, on_delete=models.CASCADE)
status = models.CharField(choices=status_opts,max_length=50)
something else like answer and marks?...
You can update this table after each question is done, and use this model to get the status. You can always Filter the data for questions of some quiz from these tables as well.
ProgressUserQuiz.objects.filter(question__in=list(quizinstance.questions.all())
I've a registration form, where user must chose one of 2 options.
Django renders all correctly, django admin also have it ok, but db records all possible choices as value.
forms.py
class UserRegisterForm(UserCreationForm):
email = forms.EmailField()
class Meta:
model = User
fields = ['username', 'email','password1','password2']
class UserProfileForm(forms.ModelForm):
terms_compliance = forms.BooleanField(label=mark_safe('I agree with terms and conditions '))
class Meta:
model = UserProfile
widgets = {'role': forms.RadioSelect}
fields = ('role','terms_compliance')
def __init__(self):
self.fields['terms_compliance'].initial = True
models.py
class UserProfile(models.Model):
user = models.OneToOneField(User, on_delete=models.CASCADE)
role_choices = [('publisher','Publisher'), ('advertiser','Advertiser')]
role = models.CharField(max_length=15, choices=role_choices, default=None)
terms_compliance = models.BooleanField()
def __str__(self):
return self.user.username
In new instance (which is user.userprofile.role_choices) I need advertiser or publisher, but all I have is: [('publisher','Publisher'), ('advertiser','Advertiser')]
If you want to provide choices in a Database Field. Do like this:
class UserProfile(models.Model):
class RoleChoice(ChoiceEnum):
PUBLISHER = 'Издатель'
ADVERTISER = 'Рекламодатель'
user = models.OneToOneField(User, on_delete=models.CASCADE)
role = models.CharField(max_length=15, choices=RoleChoice.choices(), default=None)
terms_compliance = models.BooleanField()
def __str__(self):
return self.user
In Views.py, populate the DB like this.
For example:
...
choice = request.query_params.get('choice') or UserProfile.RoleChoice.PUBLISHER.value
...
For more details read from here: https://django-mysql.readthedocs.io/en/latest/model_fields/enum_field.html
I have the following models
class Company(models.Model):
name = models.CharField(max_length=100)
description = models.TextField(
max_length=500,
blank=True,
help_text='Any text to describe a company'
)
url = models.URLField('company URL', blank=True, null=True)
email = models.EmailField(blank=True, null=True)
created_on = models.DateTimeField('date created', default=timezone.now)
class Meta:
verbose_name = 'company'
verbose_name_plural = 'companies'
ordering = ['name', '-created_on']
def __repr__(self):
return '<Company {0.name}>'.format(self)
def __str__(self):
return self.name
class Project(models.Model):
name = models.CharField(max_length=100)
description = models.TextField(
max_length=500,
blank=True,
help_text='Any text to describe the project'
)
company = models.ForeignKey(
Company,
on_delete=models.PROTECT,
)
created_on = models.DateTimeField('date created', default=timezone.now)
class Meta:
verbose_name = 'project'
verbose_name_plural = 'projects'
ordering = ['-created_on', 'company']
permissions = (
("can_view_project",
"Can view all project related work"),
)
def __repr__(self):
return '<Project {0.name}>'.format(self)
def __str__(self):
return self.name
class Worker(models.Model):
description = models.TextField(
max_length=500,
blank=True,
help_text='Optional. Describe what the worker does or who they are'
)
user = models.ForeignKey(settings.AUTH_USER_MODEL)
company = models.ForeignKey(Company)
class Meta:
order_with_respect_to = 'user'
def __repr__(self):
return '<Worker {0.id}'.format(self)
def __str__(self):
return self.user.get_fullname()
The problem
I would like to add a ManyToMany relationship between Project and Worker so that I can view
a list of workers under a certain project. However, I want to make sure that a worker can only
be added to a project if they are both part of the same company.
I was planning on using a junction table with a ForeignKey to both of their company attributes,
but according to the django docs, a foreignkey can only be used once per model
(https://docs.djangoproject.com/en/1.10/topics/db/models/#extra-fields-on-many-to-many-relationships)
How do I make sure that the many to many relationship between the two tables is limited to the same company?
Is there perhaps another way to ensure that workers cannot work on projects outside of their own company?
Assuming you define the many to many relationship this way in the Project model:
workers = ManyToManyField(Worker)
Assuming you have a model form named ProjectForm to create or modify projects. You can define a clean function in this form:
def clean(self):
cleaned_data = super(ProjectForm, self).clean()
for w in cleaned_data['workers']:
if w.company.id != cleaned_data['company'].id:
self.add_error('workers', your_error_message)
break
return cleaned_data
Hope this help.