My Post model have list of authors id
class Post(Document):
authors_id = ListField(IntField(required=True), required=True)
But sometime I need to use default Django User class. How most rapidly I can do it?
(I'm using sqlite for users and sessions and MongoDB (mongoengine ODM) for other. Don't ask why:))
I was tried to write it:
def get_authors(self):
authors = list()
for i in self.authors_id:
authors.append(get_user(IntField.to_python(self.authors_id[i])))
return authors
...and it raises 'list index out of range' exception. (authors id not empty, really). What I'm doing wrong?
Not sure about the to_python method but since you are looping through the authors_id, there is no need to do
authors.append(get_user(IntField.to_python(self.authors_id[i])))
You should be good with
authors.append(get_user(IntField.to_python(i)))
Instead of
IntField.to_python(self.authors_id[i]))
I think you just need to do:
IntField.to_python(i)
In Python the 'for i in some_list' construction gives you elements of the list, not integer indexes.
You said that you were getting this error:
and unbound method to_python() must be called with IntField instance as first argument (got int instance instead)
I got a similar error from MongoEngine. In my case the problem was that I defined the field like this:
foo_id = IntField
The correct way to define it is:
foo_id = IntField()
When I added the parenthesis, the problem went away.
Related
I'm trying to put a placeholder in a Select2 field, by putting empty_label in the field. Now i get the error:
TypeError: __init__() got multiple values for keyword argument 'empty_label'
Here is my code:
self.fields['work_types'] = ModelMultipleChoiceField(
queryset=WorkTypes.objects.filter(
white_label_client=logged_in_user.white_label_client,
deleted=False),
empty_label='Type',
required=False)
What do i have to change?
According to the comments here, it is a current bug in Django. One of the users said:
"Looking at it, I would say that this is by design. You shouldn’t use an empty label on a multiple choice field. Perhaps this should be clarified in the docs.
Saying that, if you really want an empty label on a multiple choice field, you could create your own class that initializes empty_label however you want it."
Further explanation
"Well, it is raising an error. It’s a Python error. Basically, you were passing a keyword argument (empty_label), and the class was passing the same keyword argument called empty_label. Expanded out, this is what was happening:"
field = forms.ModelMultipleChoiceField( queryset = Imodelclass.objects.all(), empty_label='------------' ) = ModelMultipleChoiceField(queryset= Imodelclass.objects.all(), empty_label=None, empty_label='------------')
"When you read the error, you see that is actually very clear in this context: You passed two arguments for the same keyword."
"I think it would be wise to mention this in the documentation; perhaps even providing a rationale why ModelMultipleChoiceField should not have an empty label. But if there is no rationale behind it, then the clear solution is to do exactly as you did: remove the empty_label keyword argument from the super call."
I'm trying to get a unique value for a field (unique within the db column).
my code (other model fields omitted):
class PlatformUserChildren(models.Model):
dashboard = models.CharField('dashboard URL', max_length=64, unique=True, default=createDashboardCode(self))
def createDashboardCode(self):
stringCheck = False
while stringCheck is False:
newString = str(uuid.uuid4())[:32]
doesStringExist = newString in self.dashboard
if not doesStringExist:
stringCheck = True
return newString
I'm getting name 'self' is not defined as an error.
What should I be passing to the function so that I can check the db column to ensure the value is unique -or- is there a built-in way of doing this?
What I've already tried or looked at:
setting unique=True for the field and using default=uuid.uuid4 - that gives me duplicate values and generates a validation error (SO link)
I'm aware of Django 1.8's UUID field, however i'm on 1.7
The problem lies in the following line (indented for better readability) as you already know and mentioned before:
dashboard = models.CharField(
'dashboard URL',
max_length=64,
unique=True,
default=createDashboardCode(self)
)
In this part:
default=createDashboardCode(self)
you're calling the method createDashboardCode with the argument self. This is wrong, because you never pass self to a method as it is passed by Python. Whenever you call the method createDashboardCode you should do it this way:
createDashboardCode()
That's it, you're not passing the argument self explicitly.
You're getting an error "name 'self' is not defined" because self is not defined. There is no variable self in your code that you can pass to the method.
Now we're one step further, but your problem won't be solved if you just apply this slight change to your code.
The return value from the method createDashboardCode will be assigned to default. That's not what you really want. You have to assign a reference of the method to default:
default = createDashboardCode
Pay attention to the missing brackets. This will call the method every time a new instance of the model is created
Define a function:
def my_function():
print "hello"
and run it in the Python interpreter:
# once like this
my_function()
# and again like this
my_function
and you'll see the difference. That should help you to better comprehend this issue.
i have three classes. Place is foreignkey of Activity(where the activity takeplace), Park and Restarant are inherited from Place.
class Activity(Model):
place=ForeignKeyField('Place')
....
class Place(Model):
address=CharField(max_length=200)
....
class Park(Place):
ticket_price=Decimal()
....
class Restarant(Place):
manager_name=CharField(max_length=100)
how can i get the real type of 'Place' in a query on Activity,so i can get the additional attributes of child type.
activity_list= Activity.objects.all()
all the activity_list[n].place are 'Place' ,neither Park or Restarant, so i can't get 'ticket_price' or 'manager_name' directly.
i have checked the model-utils, and can't find a easy way to do this.
any help will be appreciated.
inspect.getmro(cls)
Return a tuple of class cls’s base classes, including cls, in method resolution order. No class appears more than once in this tuple. Note that the method resolution order depends on cls’s type. Unless a very peculiar user-defined metatype is in use, cls will be the first element of the tuple.
try:
import inspect
for activity in activity_list:
print inspect.getmro(activity.place)
or try :
for activity in activity_list:
print activity.place._type()
try:
activity_list= Activity.objects.all()
for act in activity_list:
for b in act.place.__class__.__bases__:
print b.__name__
I use Django Inheritance Managers for this, from django-model-utils. It allows you to do exactly what you want...you said you checked model-utils to do this, but it didn't work. It should work -- what did you try with django-model-utils? You need to add this line to the parent model of Place:
objects = InheritanceManager()
I haven't tried this with your exact model design, but have you tried something like:
places = Activity.objects.all().values_list('place_id', flat=True)
places_of_right_type = Place.objects.filter(pk__in=places).select_subclasses()
?
------ UPDATE --------
Not sure this will work, but throwing it out there as an idea...would only work for a get(), not all():
places = Activity.objects.get(pk=#).place.objects.select_subclasses()
The docs say that you can call select_subclasses() on the InheritanceManager itself, which is stored in .objects.
I have a database of exhibition listings related by foreign key to a database of venues where they take place. Django templates access the venue information in the query results through listing.venue.name, listing.venue.url, and so on.
However, some exhibitions take place in temporary venues, and that information is stored in the same database, in what would be listing.temp_venue_url and such. Because it seems wasteful and sad to put conditionals all over the templates, I want to move the info for temporary venues to where the templates are expecting info for regular venues. This didn't work:
def transfer_temp_values(listings):
for listing in listings:
if listing.temp_venue:
listing.venue = Venue
listing.venue.name = listing.temp_venue
listing.venue.url = listing.temp_venue_url
listing.venue.state = listing.temp_venue_state
listing.venue.location = listing.temp_venue_location
The error surprised me:
ValueError at /[...]/
Cannot assign "<class 'myproject.gsa.models.Venue'>": "Exhibition.venue" must be a "Venue" instance.
I rather thought it was. How do I go about accomplishing this?
The error message is because you have assigned the class Venue to the listing, rather than an instance of it. You need to call the class to get an instance:
listing.venue = Venue()
This seems like it should be dead simple, so I must be missing something. I just want to set the value of a field in my model instance by name. Say I have:
class Foo(Model):
bar = CharField()
f = Foo()
I want to set the value of bar by name, not by accessing the field. So something like:
f.fields['bar'] = 'BAR"
instead of
f.bar = 'BAR'
I've tried setattr but it doesn't persist the value in the database. I also tried going through _meta.fields but got various errors along the way.
If you modify the value via setattr, you need to remember to save the model after modifying it. I've been bitten in the past where I changed the values but forgot to save the model, and got the same result.
setattr(f, 'bar', 'BAR')
f.save()
We may have to see more code.
setattr(f, 'bar', 'BAR')
should work as this is how Django does it internally.
Make sure you are calling 'save', as well.