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Reorganizing ManyToMany models into a different order

I have an setup similar to this.
class Author(models.Model):
first_name = models.CharField(max_length=30)
last_name = models.CharField(max_length=40)
books = models.ManyToManyField(Book)
def __unicode__(self):
return self.title
class Book(models.Model):
title = models.CharField(max_length=100)
author = models.ForeignKey(Author)
def __unicode__(self):
return self.title
Now in my admin panel I can select an author and add Books underneath that specific author. When I print out all the books for each author it prints them in the order that they were added in the admin panel.
Is it possible to modify the order in the admin panel so that when they print, they print in the order of the admin panel?
admin.py
#admin.register(Author)
class AuthorAdmin(admin.ModelAdmin):
pass
#admin.register(Book)
class BookAdmin(admin.ModelAdmin):
pass

You can add inside every model a class Meta with ordering atribute, to get items in a certain order.
class Book(models.Model):
...
class Meta:
ordering = ['author']
Maybe it helps you.

as i understand you use TabularInline for books if that's right so you just need to make simple function called get_queryset
def get_queryset(self, request):
return super(BookInlineAdmin, self).get_queryset(request).order_by('YOURFIELD')

the model field's form disappears in django admin

I have two models, which are User and Record. Each has several fields.
from django.db import models
class User(models.Model):
openid = models.CharField(max_length=20)
nickname = models.CharField(max_length=20,null=True)
def __str__(self):
return self.nickname
class Record(models.Model):
expression = models.CharField(max_length=100)
user = models.ForeignKey(User)
time = models.DateTimeField(auto_now_add=True)
def __str__(self):
return self.expression
I register them in admin.py
from django.contrib import admin
from .models import User,Record
class RecordAdmin(admin.ModelAdmin):
list_display = ('expression','user','time')
class UserAdmin(admin.ModelAdmin):
empty_value_display = "空"
list_display = ('openid','nickname')
admin.site.register(User,UserAdmin)
admin.site.register(Record,RecordAdmin)
it works well in django admin initially. but one day, the fields of the Record model disppeared. It looks like
.
No field displays. It makes me unable to modify or add the values of the Record model. The other model User works well and all data exists in database. So why?

I think you just have to add on_delete=models.CASCADE in your ForeignKey Field. When you are using this kind of field, you have to specify the comportment when you make an update, a delete or anything else on this field.
So your script should be like this :
class Record(models.Model):
expression = models.CharField(max_length=100)
user = models.ForeignKey(User, on_delete=models.CASCADE)
time = models.DateTimeField(auto_now_add=True)
def __str__(self):
return self.expression
This is the result :
Edit :
You can also modify null=True by default=null
class User(models.Model):
openid = models.CharField(max_length=20)
nickname = models.CharField(max_length=20,default=null)
def __str__(self):
return self.nickname

Update Table Relationship in Django Admin

I'm trying to create a directory of sites, I'm new in Django. What I need is: one site can have many payment processors and one payment processors (Paypal, Payza, etc) can belong to many sites. I'm trying to create a table relationship to represents this. My models are like this:
# Models.py
class Sites(models.Model):
name = models.CharField(max_length=75)
link = models.CharField(max_length=150)
description = models.TextField(blank=True, null=True)
def __str__(self):
return self.name
class PaymentProcessors(models.Model):
name = models.CharField(max_length=75)
def __str__(self):
return self.name
class Sites_PaymentProcessors(models.Model):
site = models.ManyToMany(Sites)
payment_processor = models.ManyToMany(PaymentProcessors)
First, I'd like to know if my models are right. If not, how can I fix it?
Second, I'm using Django Admin site to create the sites and payment processors, how can I populate automatically my Sites_PaymentProcessors table with the relation between Sites and Payment_Processors when I add a new Site?

I would slightly change the models to accomodate ManyToManyFields like this:
class Sites(models.Model):
name = models.CharField(max_length=75)
link = models.CharField(max_length=150)
description = models.TextField(blank=True, null=True)
def __str__(self):
return self.name
class PaymentProcessors(models.Model):
name = models.CharField(max_length=75)
sites = models.ManyToManyField('Sites', related_name='payment_processors')
def __str__(self):
return self.name
Now, if you want custom fields or store more information along with the relationship, you can make use of the through table
For example, if you want to associate the amount limit or something more custom:
class Sites(models.Model):
name = models.CharField(max_length=75)
link = models.CharField(max_length=150)
description = models.TextField(blank=True, null=True)
def __str__(self):
return self.name
class PaymentProcessors(models.Model):
name = models.CharField(max_length=75)
sites = models.ManyToManyField('Sites', related_name='payment_processors', through='SitePaymentProcessor')
def __str__(self):
return self.name
from django.core.validators import MaxValueValidator
class SitePaymentProcessor(models.Model):
site = models.ForeignKey('Site')
payment_processors = models.ForeignKey('PaymentProcessors')
amount_limit = models.IntegerField(default=1000,
validators=[
MaxValueValidator(100)
])
Now, again this is just an example.
Now, registering the admin classes would enable you to populate data into the models via the admin interface.
To auto-populate a large dataset, I would consider using fixtures rather than populating elements individually.

Models bleeding together in models.py?

In Django I'm trying to write a ModelForm for a ContactForm and when I try to load the page containing the form it says that it doesn't exist. Then when I try to render the other form I had previously written it says that
Caught AttributeError while rendering: 'CashtextsForm' object has no attribute 'subject'
'Subject' is a field in the form that I was trying to render in ContactForm. So is there some certain order I have to list them in models.py? Here's that code:
# Create your models here.
from django.db import models
from django.forms import ModelForm
class Cashtexts(models.Model):
cashTexts = models.CharField(max_length=100, blank=True) #change me to a website filter
superPoints = models.CharField(max_length=100, blank=True)#chance to "superPoints _Username"
varolo = models.CharField(max_length=100, blank=True)
swagbucks = models.CharField(max_length=100, blank=True)
neobux = models.CharField(max_length=100, blank=True)
topline = models.CharField(max_length=100, blank=True)
Paidviewpoint = models.CharField(max_length=100, blank=True)
cashcrate = models.CharField(max_length=100, blank=True)
def __unicode__(self):
return self.cashcode
class Contact(models.Model):
sender = models.EmailField()
subject = models.CharField(max_length=25)
message = models.TextField()
class CashtextsForm(ModelForm):
class Meta:
model = Cashtexts
def __unicode__(self):
return self.subject
class ContactForm(ModelForm):
class Meta:
model = Contact
I previously had them arranged as Model-Modelform, Model-Modelform but hereit shows them as the way I now currently have them.
Also Is there any advantages to write just forms? Right now I'm more comfortable writing model forms over forms(I dont imagine they are much differnt) but if I only wrote model forms would I be missing out on features? So is there anything I missed on how t write multiple forms in models.py or did I have them written worng? or can i not create them via the command syncdb?

The __unicode__(self) method should be part of your Contact class
class Contact(models.Model):
sender = models.EmailField()
subject = models.CharField(max_length=25)
message = models.TextField()
def __unicode__(self):
return self.subject
It doens't make sense inside CashtextsForm as that does not "know" a subject attribute.

Yes, your form really does not have subject, just remove __unicode__ definition and everything will be ok.
This is because of declarative style of django code. If you want to inspect your objects use pdb module and dir builtin.
You will use ModelForm subclasses almost every time, but sometimes you will need a form which can not be built from model. In this case django will help you to describe such form and to use form clean and field validation.

the subject field is defined in the model and not in the modelform, since a modelform can be initialized without a model instance it is not safe to do something like this:
def __unicode__(self):
return self.instance.subject
What you can do (but I do not really see the point of doing this):
def __unicode__(self):
if getattr(self, 'instance') is not None:
return self.instance.subject
return super(CashtextsForm, self).__unicode__()

Is there an order in which models are generated into database?

In my project I need to change the location where files are being uploaded. This is done using a FileSystemStorage. The path were the files are uploaded should be easy to configure, for example using the Django Admin.
from django.core.files.storage import FileSystemStorage
from django.db import models
class Setting(models.Model):
entry = models.CharField(primary_key=True, db_column="entry", max_length=50)
value = models.CharField(db_column="value", max_length=250, blank=True, null=True)
def __unicode__(self):
return "%s" %(self.entry)
class Meta:
db_table = 'settings'
verbose_name = 'Setting'
verbose_name_plural = 'Settings'
fs = FileSystemStorage(location=Setting.objects.get(entry__exact='upload_path').value)
def generate_filename(instance, filename):
...
class FileImport(models.Model):
data_file = models.FileField(_('Data file'), upload_to=generate_filename, storage=fs)
I receive this error:
django.db.utils.DatabaseError:
relation "settings" does not exist
LINE 1: ...ELECT "settings"."entry", "settings"."value" FROM "settings"...
for the line where FileSystemStorage is being created. Is there a way of telling Django to create table settings(for Setting objects) first and then fill this table with some fixtures?

That won't solve your problem, since the Settings table still won't be populated. Move it into a class attribute that gets initialized the first time it's instantiated.