I'm trying to use a ManyToMany relationship and it is giving me the following error:
NameError: name 'ManyToManyField' is not defined
Background: Building a to do app where users have (many) projects, projects have (many) lists of tasks and projects have (many) tags that characterise them.
Here is my models.py, any help catching the error would be greatly appreciated.
from django.db import models
from django.contrib.auth.models import User
#Not sure if I need the ID's. They may be superfluous. Ask in the lab today.
#Used to list collaborators on projects and track friends lists
#Borrowed from http://stackoverflow.com/a/1113039/1254402
class SeparatedValuesField(models.TextField):
__metaclass__ = models.SubfieldBase
def __init__(self, *args, **kwargs):
self.token = kwargs.pop('token', ',')
super(SeparatedValuesField, self).__init__(*args, **kwargs)
def to_python(self, value):
if not value: return
if isinstance(value, list):
return value
return value.split(self.token)
def get_db_prep_value(self, value):
if not value: return
assert (isinstance(value, list) or isinstance(value, tuple))
return self.token.join([unicode(s) for s in value])
def value_to_string(self, obj):
value = self._get_val_from_obj(obj)
class UserProfile(models.Model):
user_id = models.CharField(max_length=100, null=True, blank=True, unique=True)
user = models.OneToOneField(User)
# The additional attributes we wish to include.
first_name = models.CharField(max_length=64)
surname = models.CharField(max_length=64)
friends = SeparatedValuesField()
picture = models.ImageField(upload_to='profile_images', blank=True)
projects = models.ManyToManyField('Project')
# This line is required. Links UserProfile to a User model instance.
# Override the __unicode__() method to return out something meaningful!
def __unicode__(self):
return self.user.username
#Project model.
#Attributes = name, website, team members
#Many users can have many projects
class Project(models.Model):
project_id = models.CharField(max_length=100, null=True, blank=True, unique=True)
name = models.CharField(max_length=128)
description = models.CharField(max_length=300)
website = models.URLField(blank=True)
team_members = SeparatedValuesField()
class List(models.Model):
#Many lists belong to one project
project = models.ForeignKey(Project)
tasks = ManyToManyField('Task')
name = models.CharField(max_length=128)
colour = models.CharField(max_length=10)
#NOTE! - Abstracting the tags (category, progress and priority) to project level.
class Task(models.Model):
#Many tasks belong to one list
belong_to_list = models.ForeignKey(List)
#Unique id for task
task_id = models.CharField(max_length=100, null=True, blank=True, unique=True)
#Standard title & description
title = models.CharField(max_length=100)
description = models.CharField(max_length=300)
#NOTE! - Abstracting the tags (category, progress and priority) to project level.
class Tag(models.Model):
project = models.ForeignKey(Project)
#UUID
task_id = models.CharField(max_length=100, null=True, blank=True, unique=True)
#User assigns each tag a colour. hex code.
colour = models.CharField(max_length=10)
In List, you are referring to ManyToManyField without referencing it via models as you do with all the other fields.
Note that the error message would have told you exactly where the problem was, so that you wouldn't have needed to post all the other irrelevant code.
Related
I am a beginner in Django. I am building a data model for a Django app, named PhoneReview. It will store reviews related to the latest mobile phone. It's table should include:
a. Brand – details on brand, such as, name, origin, manufacturing since, etc
b. Model – details on model, such as, model name, launch date, platform, etc
c. Review – review article on the mobile phone and date published, etc
d. Many-to-many relationship between Review and Model.
Here are my codes in models.py:
from django.db import models
from django.template.defaultfilters import slugify
# Create your models here.
class Brand(models.Model):
brandName = models.CharField(max_length=100)
origin = models.CharField(max_length=100)
manufacturingSince = models.CharField(max_length=50, default='null')
def __str__(self):
return self.brandName
class PhoneModel(models.Model):
modelName = models.CharField(max_length=100)
launchDate = models.CharField(max_length=100)
platform = models.CharField(max_length=100)
def __str__(self):
return self.modelName
class Review(models.Model):
model_name_many_to_many = models.ManyToManyField(PhoneModel)
reviewArticle = models.CharField(max_length=1000)
datePublished = models.DateField(auto_now=True)
slug = models.SlugField(max_length=150, default='null')
def __str__(self):
return self.reviewArticle
Are my codes correct? Am I in the right direction?
Don't use camelCase in model fields. Use snake_case. Second thing is, when you want field to be default 'null', just use null=True, blank=True(optional value).
I've also provided related_name to your ManyToManyField, so you can use PhoneModelInstance.reviews.all() to get your all reviews for this specific Phone model. For large fields containing text, use TextField.
Edit
I've also added foreign key in PhoneModel which points to the Brand.
from django.db import models
from django.template.defaultfilters import slugify
# Create your models here.
class Brand(models.Model):
brand_name = models.CharField(max_length=100)
origin = models.CharField(max_length=100)
manufacturing_since = models.TextField(null=True, blank=True)
def __str__(self):
return self.brand_name
class PhoneModel(models.Model):
brand_fk = models.ForeignKey(Brand)
model_name = models.CharField(max_length=100)
launch_date = models.CharField(max_length=100)
platform = models.CharField(max_length=100)
def __str__(self):
return self.model_name
class Review(models.Model):
phone_model = models.ManyToManyField(PhoneModel, related_name='reviews')
review_article = models.TextField()
date_published = models.DateField(auto_now=True)
slug = models.SlugField(max_length=150, null=True, blank=True)
def __str__(self):
return self.review_article
I have a model in django, in which there will be several roles - regular user, admin and manager. Each of them will be able to do something else. Is the following model OK to work correctly?
class Team(models.Model):
name = models.CharField('Name', max_length=128)
users = models.ManyToManyField(User)
admins = models.ManyToManyField(User)
managers = models.ManyToManyField(User)
def __str__(self):
return self.name
This might work. If the number of roles is large, or dynamic (as in roles can be added, removed, renamed, updated). You could introduce a ternary relation, like:
from django.conf import settings
class Role(models.Model):
name = models.CharField(max_length=128)
class Team(models.Model):
name = models.CharField('Name', max_length=128)
members = models.ManyToManyField(settings.AUTH_USER_MODEL, through='Membership')
def __str__(self):
return self.name
class Membership(models.Model):
user = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
team = models.ForeignKey(Team, on_delete=models.CASCADE)
role = models.ForeignKey(Role, on_delete=models.PROTECT)
I'm new to Python (and pretty inexperienced at programming in general), but I have an issue I can't for the life of me figure out.
I'm trying to pre-populate a field in my database with the name of an instance from another model/class in my database. The model with the field I want to pre-populate is an "instance" of the model instance from which I'm trying to grab the name, and has a foreign key to that instance.
Goal: 1) User selects the parent of the object by assigning the foreign key to the parent 2) A function grabs the name of the parent instance matching the foreign key the user selected. 3) the result from that function is used as the default value for the field.
Here's the code:
class Injury(models.Model):
id = models.UUIDField(primary_key=True, default=uuid.uuid4, help_text='Unique ID for this particular injury')
name = models.CharField(max_length=200, help_text='Enter an injury or complication (e.g. respiratory failure)')
description = models.TextField(max_length=1000, blank=True, help_text='Describe the injury')
time_to_onset = models.PositiveIntegerField(blank=True, validators=[MaxValueValidator(10000)], help_text='Enter expected time from trigger until injury/complication onset')
findings = models.TextField(max_length=1000, blank=True, help_text='Enter the signs and symptoms of the injury or complication')
vitals_trends = models.TextField(max_length=1000, blank=True, help_text='Enter the vitals changes due to the injury')
class Meta:
ordering = ['name']
def __str__ (self):
return self.name
def get_absolute_url(self):
return reverse('Injury-detail', args=[str(self.id)])
class Injury_Instance(models.Model):
id = models.UUIDField(primary_key=True, default=uuid.uuid4, help_text='Unique ID for this particular injury')
parent_case = models.ForeignKey(PFC_Case, on_delete=models.SET_NULL,null=True)
injury_model = models.ForeignKey(Injury, on_delete=models.SET_NULL, null=True)
def set_injury_name(self):
for injuries in Injury.all()
if injury_model == injuries
break
return Injury.name
name = dislay_models.CharField(default=set_injury_name(self,Injury,injury_model), max_length=100)
triggered_by = models.ForeignKey('self', on_delete=models.SET_NULL, null=True, blank=True)
def __str__ (self):
return self.name
def get_absolute_url(self):
return f'{self.id} ({self.Injury.name})'
The problem area is def set_injury_name and Injury_Instance.name
Thanks!!!
Edit:
I tried the following code, but I'm getting the error 'NameError: name 'self' is not defined'
class Injury_Instance(models.Model):
id = models.UUIDField(primary_key=True, default=uuid.uuid4, help_text='Unique ID for this particular injury')
parent_case = models.ForeignKey(PFC_Case, on_delete=models.SET_NULL,null=True)
injury_model = models.ForeignKey(Injury, on_delete=models.SET_NULL, null=True)
def get_injury_name(self):
return self.name
injury_name=get_injury_name(self)
name = models.CharField(default=injury_name, max_length=100)
triggered_by = models.ForeignKey('self', on_delete=models.SET_NULL, null=True, blank=True)
def __str__ (self):
return self.name
def get_absolute_url(self):
return f'{self.id} ({self.Injury.name})'
You don't need to store the name of your foreign key field as you always can access it with:
self.injury_model.name
If you need to get access it just by name you can write a property in Injury_Instance model.
#property
def name(self):
return self.injury_model.name
I am trying to get a queryset but it is not displaying anything. Basically, I want to get the Asset objects that are assigned via foreign key to an employee, which is a foreign key of the signed in user.
views.py
def get_queryset(self):
assetlist = Asset.objects.filter(organisation__employee__user=self.request.user)
print(assetlist)
return assetlist
models.py
class Employee(models.Model):
name = models.CharField("Employee Name", max_length=50, blank=False)
email = models.CharField("Employee Email", max_length=50, blank=True)
user = models.ForeignKey(User)
clientID = models.ForeignKey(Organisation)
def save(self):
self.name = self.user.get_full_name()
self.email = self.user.email
super(Employee, self).save()
def __str__(self):
return self.name
class Asset(models.Model):
name = models.CharField("Asset Name", max_length=30, primary_key=True)
organisation = models.ForeignKey(Organisation)
def __str__(self):
return self.name
class Organisation(models.Model):
name = models.CharField("Organisation Name", max_length=50, blank=False)
location = models.TextField("Organisation Address", max_length=200, blank=True)
tel = models.CharField("Telephone Number", max_length=20)
def __str__(self):
return self.name
There is no employee field inside organisation. It's an reversed relation, there are many employees attached so you can't query it like that.
But there is something called related_name in django foreign keys, with use of that, your query should look like that:
assetlist = Asset.objects.filter(organisation__employee_set__user=self.request.user)
or if you specify your own related_name into employee -> organisation relation:
clientID = models.ForeignKey(Organisation, related_name="employees")
it will look like this:
assetlist = Asset.objects.filter(organisation__employees__user=self.request.user)
The answer was to approach from another model, as seen below:
assetlist = Sensor.objects.filter(asset__organisation__employee__user=self.request.user)
You have written wrong code. You want an Asset object by using:
assetlist = Asset.objects.filter(organisation__employee__user=self.request.user)
But you clearly can see in your models.py that there is no relationship between Organisation and Employee, then how can you get a result using organisation__employee...?
You should first create a ForeignKey field to relate with Employee model then your code will work fine.
I need two Django models: first with Users, second with Projects.
Between them I need many-to-many relationship with an additional field(s).
How to make the below code working?
from django.db import models
class User(models.Model):
name = models.CharField('Name', max_length=50)
projects = models.ManyToManyField(Project, through='UserProjects')
def __str__(self):
return self.name
class Project(models.Model):
name = models.CharField('Name', max_length=50)
users = models.ManyToManyField(User, through='UserProjects')
def __str__(self):
return self.name
class UserProjects(models.Model):
user = models.ForeignKey(User)
project = models.ForeignKey(Project)
is_active = models.BooleanField('Active')
At the end User.projects should return Projects for specified User
and in the same way Project.users should return Users for specified Project.
There's no need to put the m2m field on both sides
Jussi pick one, and Django will automatically create a reverse relationship for the other direction.
from django.db import models
class User(models.Model):
name = models.CharField('Name', max_length=50)
def __str__(self):
return self.name
class Project(models.Model):
name = models.CharField('Name', max_length=50)
users = models.ManyToManyField(User, through='UserProjects', related_name='projects')
def __str__(self):
return self.name
class UserProjects(models.Model):
user = models.ForeignKey(User)
project = models.ForeignKey(Project)
is_active = models.BooleanField('Active')
Here is the simplest solution in my opinion:
from django.db import models
class User(models.Model):
name = models.CharField('Name', max_length=50)
class Project(models.Model):
name = models.CharField('Name', max_length=50)
class UserProjects(models.Model):
user = models.ForeignKey(User, related_name='projects')
project = models.ForeignKey(Project, related_name='users')
is_active = models.BooleanField('Active')
In above User.projects returns Projects for specified User and also Project.users returns Users for specified Project.