Rest-framework support post data in the web.
But about ForeignKey,it shows just the same "Objects" without feature to make sure which is what I want.
this is my code:
server models:
node = models.ForeignKey(
Node,
related_name='server',
null=True,
)
serializers:
class ServerSerializer(serializers.ModelSerializer):
class Meta:
model = Server
fields = ( 'node')
How can I get the server objects' feature instead of "Server Object"?
You should write a __unicode__() method for your model to have more readable representation. Assuming your model has a field name which contains the name of the object, do something like:
class Server(models.Model):
name = models.CharField(max_length=100)
def __unicode__(self):
return self.name
In Case you are using Django with Python3 you should use instead the str():
class Server(models.Model):
name = models.CharField(max_length=100)
def __str__(self):
return self.name
Related
I would like to display a model in the django admin but with the logic to choose between 2 models to display.
Current Implementation:
Models
class User(models.Model):
created = models.DateTimeField(auto_now_add=True, null=True)
last_updated = models.DateTimeField(auto_now=True)
name = models.CharField(max_length=30, blank=True)
class ExpectedNames(User):
class Meta:
proxy=True`
Admin
#admin.register(ExpectedNames)
class ExpectedNamesAdmin(admin.ModelAdmin):
date_hierarchy = 'created'
What I Would like to DO: # something like this
Models
class User(models.Model):
created = models.DateTimeField(auto_now_add=True, null=True)
last_updated = models.DateTimeField(auto_now=True)
name = models.CharField(max_length=30, blank=True)
class User2(models.Model):
created = models.DateTimeField(auto_now_add=True, null=True)
last_updated = models.DateTimeField(auto_now=True)
name = models.CharField(max_length=30, blank=True)
class ExpectedNames(User):
class Meta:
proxy=True
if name == "Rick":
return User
else:
return User2
Admin
#admin.register(ExpectedNames)
class ExpectedNamesAdmin(admin.ModelAdmin):
date_hierarchy = 'created'
Any suggestions not sure if this is the correct way to do this.
I think this is not possible as it states in the Django Documentation:
Base class restrictions:
A proxy model must inherit from exactly one non-abstract model class. You can’t inherit from multiple non-abstract models as the proxy model doesn’t provide any connection between the rows in the different database tables. A proxy model can inherit from any number of abstract model classes, providing they do not define any model fields. A proxy model may also inherit from any number of proxy models that share a common non-abstract parent class.
https://docs.djangoproject.com/en/dev/topics/db/models/#proxy-models
I use magic method new in same situation.
I have model Documen with field document_type. If document_type is 'contract' i want ContractProxy, if 'offer' - OfferProxy.
For do this I create new proxy:
class RelatedDocumentProxy(Document):
class Meta:
proxy = True
def __new__(cls, *args, **kwargs):
doc_type = args[1]
if doc_type == 'contract':
return ContractProxy(*args, **kwargs)
return OfferProxy(*args, **kwargs)
document_type is first field and will first arg who pass to method
I'm a newbie in Django, and I don't know how to this.
I have a model 'Seller':
class Seller(models.Model):
seller_name = models.CharField(max_length=50)
def __str__(self):
return self.seller_name
and a model 'Item':
class Item(models.Model):
seller = models.ForeignKey(Seller, on_delete=models.CASCADE)
item_name = models.CharField(max_length=100)
item_category = models.CharField(max_length=100, choices=ALL_CATEGORIES)
item_price = models.FloatField()
item_preview = models.ImageField(upload_to='previews/<the seller's name>')
def __str__(self):
return self.item_name
connected via ForeignKey to Seller.
In this model, I have an ImageField, and I want it to upload the files to previews/Seller's name directory, but I don't know how to access the Seller's name from Item. Is it possible? Or am I doing something I am not supposed to? Because I couldn't find any similar cases in the internet.
You can access Seller name like this.
item = Item.objects.get(<condition>)
item.seller.seller_name
If you are using filter
items = Item.objects.filter(<condition>)
items[0].seller.seller_name #You need to provide index in queryset
or
for item in items:
item.seller.seller_name
you can't provide a path like that. You can either use a callable in upload_to or can use the lambda function.
item_preview = models.ImageField(upload_to=lambda instance: 'previews/{0}'.format(instance.seller.seller_name))
If you use upload_to callable
item_preview = models.ImageField(upload_to=upload_file_handler)
def upload_file_handler(instance, filename):
return 'previews/{0}'.format(instance.seller.seller_name)
I have an app which allows to associate to each client multiple boards, boards where I can upload files relevant for the client to make decisions about how the website page in question will look.
So the relationships I need to model are:
one client, multiple boards;
one board, one client;
one board, multiple files;
Let's concentrate on the first two
models.py
class Board(models.Model):
title = models.CharField(max_length=120, verbose_name="Titolo")
description = models.TextField()
files = models.FileField( null=True, blank=True, upload_to = 'clients_download_area', verbose_name = 'Client Reserved File')
date = models.DateTimeField(auto_now_add=True, verbose_name = 'Data di pubblicazione')
def __str__(self):
return str(self.title)
class Client(models.Model):
name = models.CharField(max_length=30)
address = models.CharField(max_length=120)
boards = models.ManyToManyField(Board, blank=True)
def __str__(self):
return str(self.name)
Ok, relationship #1 is done. But what if I need to know which client is associated to a board (relationship #2)?
If I set a new field to Board Class
class Board(models.Model):
[...]
client = models.ForeignKey(Client, blank = True)
of course, when I makemigrations Django complains because it does not know what Client is, since I define it in the next model.
How can I design this DB?
Thank you in advance for any help you could provide
The problem here is that you reference to an identifer (here Client), before it is constructed (since Board is defined before the Client class).
Django has some support for this: you can pass strings that contain the name of the model. In the same app, you can just use ClassName, for another app, you can use other_app.ClassName, like the documentation says:
If you need to create a relationship on a model that has not yet been defined, you can use the name of the model, rather than the model
object itself:
from django.db import models
class Car(models.Model):
manufacturer = models.ForeignKey(
'Manufacturer',
on_delete=models.CASCADE,
)
# ...
class Manufacturer(models.Model):
# ...
pass
So here you can write it like:
class Board(models.Model):
title = models.CharField(max_length=120, verbose_name="Titolo")
description = models.TextField()
files = models.FileField( null=True, blank=True, upload_to = 'clients_download_area', verbose_name = 'Client Reserved File')
date = models.DateTimeField(auto_now_add=True, verbose_name = 'Data di pubblicazione')
client = models.ForeignKey(
'Client',
related_name='my_boards'
on_delete=models.CASCADE
)
def __str__(self):
return str(self.title)
class Client(models.Model):
name = models.CharField(max_length=30)
address = models.CharField(max_length=120)
boards = models.ManyToManyField(Board, blank=True)
def __str__(self):
return str(self.name)
Note however that you already defined a ManyToManyField relation from Client to Board. Although it is possible it is not very common that two such relations exists simultaneously.
If you define a ForeignKey relationship from Board to Client, then Django automatically creates a reverse relationship (with the related_name), such that some_client.my_boards, is a manager of all the related Boards.
I think you can pass model class name instead of the class itself:
class Board(models.Model):
[...]
client_id = models.ForeignKey('Client', blank=True)
I have a Django model used extensively in my app. I'd like to create another model that inherits from that one so I can continue using the original model throughout the code, but move a field to the new model
I have:
class MyModel(models.Model):
field1 =...
field2=...
field3=...
I want to move field3 to a new model:
class MyModel2(MyModel):
field3=...
Then I'd like MyModel instances where field3 is not null to become MyModel2 instances.
The code would continue to refer to MyModel, but in some special cases, I'd use MyModel2 instead. Is this possible? Advisable? Is there a better way? I considered making a base abstract model that both could inherit from, but then you can't use the abstract model in forms and things.
Actual model:
class Unit(models.Model):
address = models.ForeignKey(Address)
name = models.CharField(max_length=500, verbose_name="Unit Name")
payments = GenericRelation("Payment", content_type_field='content_type', object_id_field='object_pk')
permissions = GenericRelation("CustomPermission", content_type_field='content_type', object_id_field='object_pk')
association = models.ForeignKey(Association, blank=True, null=True)
def __unicode__(self):
return self.name
"association" is the field I want to move to another model.
I guess you should use abstract = True https://docs.djangoproject.com/en/1.10/topics/db/models/#abstract-base-classes
class MyModel(models.Model):
field1 =...
field2=...
field3=...
class Meta:
abstract = True
class MyModel2(MyModel):
field4=...
class AssociationBase(models.Model):
association = models.ForeignKey(Association, blank=True, null=True)
class Meta:
abstract = True
class Unit(AssociationBase):
address = models.ForeignKey(Address)
name = models.CharField(max_length=500, verbose_name="Unit Name")
payments = GenericRelation("Payment", content_type_field='content_type', object_id_field='object_pk')
permissions = GenericRelation("CustomPermission", content_type_field='content_type', object_id_field='object_pk')
def __unicode__(self):
return self.name
I am trying to create a Many-To-Many relationship between two models- Author and Book. My use-case is that I should be able to add a new book to the database with an author that already exists in the database.
models.py
class Author(models.Model):
author_id = models.CharField(max_length=20, primary_key=True)
name = models.CharField(blank=True, null=True)
def __unicode__(self):
return self.name
class Meta:
ordering = ('author_id',)
class Book(models.Model):
title = models.CharField(max_length=50, primary_key=True)
authors = models.ManyToManyField(Author)
def __unicode__(self):
return self.title
class Meta:
ordering = ('title',)
serializers.py
class AuthorSerializer(serializers.ModelSerializer):
class Meta:
model = Author
fields = ('author_id', 'name')
class BookSerializer(serializers.ModelSerializer):
authors = AuthorSerializer(many=True)
class Meta:
model = Book
fields = ('title', 'authors')
def create(self, validated_data):
book = Book.objects.create(name=validated_data['title'])
for item in validated_data['authors']:
author = Author.objects.get(author_id=item['author_id'])
book.authors.add(author)
return book
Let's say my Author table already has an Author:
1, George RR Martin
Now if I want to add a new book with an existing author, this is the request I send using httpie:
http -j POST http://localhost/books title="The Winds of Winter" authors:='[{"author_id":"1"}]'
and when I do, I get this error:
Output Error
{
"authors": [
{
"author_id": [
"This field must be unique."
]
}
]
}
It seems like the AuthorSerializer is being called which checks the provided author_id against the ones in the database already and throws this error.
Any help on this would be appreciated.
Is there a specific reason you have to use a custom PK field?
Django automatically creates primary key fields for you. If you simply delete that field from your model and your serializer (and create/run a migration on your database), you won't have to specify the pk in your POST call from your frontend, and Django will create an AutoField that auto-increments your model's id:
class Author(models.Model):
# Remove this line and run makemigrations.
# author_id = models.CharField(max_length=20, primary_key=True)
name = models.CharField(blank=True, null=True)
def __unicode__(self):
return self.name
class Meta:
ordering = ('author_id',)
If not, consider using an models.AutoField rather than models.CharField for your primary key field, and again, don't include this in your POST call.
Note, that if you already have a big database created, you might have to do some intricate work in your migration, a la this answer: