Django model form and objects database id - django

I have a complex django object, which has properties of other class types. This gets like this:
class Order:
contractor - type Person
some other fields....
In my form I'd like to be able to either choose existing Person object from the dropdown or add a new one with a form. I've managed to create forms and appropriate workflow, but the problem is with saving the Order itself, I simply can't get the id of a saved Person instance. I'm doing sth like this:
def make_order(request):
if request.method == 'POST':
parameters = copy.copy(request.POST)
contractor_form = ContractorForm(parameters)
if contractor_form.is_valid():
contractor_form.save()
parameters['contractor'] = ???
form = OrderForm(parameters)
if form.is_valid():
form.save()
return HttpResponseRedirect('/orders/')
else:
form = OrderForm()
contractor_form = ContractorForm()
return render_to_response('orders/make_order.html', {'order_form' : form, 'contractor_form' : contractor_form})
So, if POST request reaches this method I first check if ContractorForm have been filled - I assume that if the form is valid, it is meant to be used. If yes, than I save it and would like to assign the saved object's database id to appropriate field for OrderForm to find it.
All my forms are ModelForms.
The questions are:
Are there better ways to do this? (choose from dropdown or add in place) - better or more pythonic ;-)
How can I get saved objects id when using ModelForms?
Edited
My ContractorForm is:
class ContractorForm(ModelForm):
class Meta:
model = Contractor
Nothing fancy.

save() should return the newly created instance.
if contractor_form.is_valid():
instance = contractor_form.save()
parameters['contractor'] = instance
where id would be instance.id, or even better instance.pk.
pk vs. id:
Regardless of whether you define a
primary key field yourself, or let
Django supply one for you, each model
will have a property called pk. It
behaves like a normal attribute on the
model, but is actually an alias for
whichever attribute is the primary key
field for the model. You can read and
set this value, just as you would for
any other attribute, and it will
update the correct field in the model.
Follow-up on comment:
Well it does work by default, so there must be something else wrong.
models.py
class Category(models.Model):
name = models.CharField(max_length=70)
slug = models.SlugField()
forms.py
from django import forms
from models import Category
class MyModelForm(forms.ModelForm):
class Meta:
model = Category
Test in shell:
In [3]: from katalog.forms import MyModelForm
In [4]: data = {'name':'Test', 'slug':'test'}
In [5]: form = MyModelForm(data)
In [6]: instance = form.save()
In [7]: instance
Out[7]: <Category: Test>
In [8]: instance.id
Out[8]: 5L

Related

Django - modelform + model property

I am trying to solve one issue about saving data in db.
This is an example how I think of it:
class MyModel(models.Model):
id = models.AutoField(primary_key=True)
fieldX = models.SomeFieldType()
#property:
def foo(self):
return self._foo
#foo.setter
def foo(self, var):
self._foo=var
class MyModelForm(models.Modelform):
class Meta:
model = models.MyModel
fields = '__all__'
The thing is I have dict that I am passing to this form (so I am not using view or any provided interaction with user directly. In dict I have some fields and what I want to do is one field that is passed to use it as model property but I do not want it to be saved in db.
So I tried something like:
form = MyModelForm(data_dict)
if form.is_valid():
form.foo = data_dict['data_for_property_not_db']
form.save()
Form does not know that my model has this property.
So basiclly what I want is to write some parts of my data_dict normaly to form and db as always ->works fine
and then I want some data_info pass to that property and use it somewhere in save() as needed without saving it to db itself.
Can you help me with this?

Django form - Can I create an object without saving it?

I have an object (myModel) which i want to create according to a form(myModelForm), I also want that the object would be related to a requiered ForeignKey object (Group) which i want to decide by myself.(i.e, don't want it to be in the form.
So if I try to use form.save() i get an error. is there a way i can add Group ForeignKey (in view) before i use save()?
My code looks something like this:
class myModel(models.Model):
myGroup = ForeignKey(Group)
normal_field1 = TextField()
...
normal_field2 = TextField()
class myModelForm(ModelForm):
class Meta:
model = myModel
fields = [normal_field1,noraml_field2]
muchas gracias
Use commit=False to create the item without persisting it to the database.
if form.is_valid():
obj = form.save(commit=False)
obj.myGroup= whatever
obj.save()

Prepopulating dynamically added formsets in edit view

I have different models in my app, the main model having multiple instances of some other models.
models.py:
class Person(models.Model):
...
class Pet(models.Model):
owner = models.ForeignKey(Person)
...
forms.py:
class PersonForm(forms.ModelForm):
class Meta:
model = Person
PetFormSet = inlineformset_factory(Person, Pet, extra = 1)
views.py:
def add_template(request):
person_form = PersonForm(prefix = 'person_form')
pet_form = PetFormSet(instance = Person(), prefix = 'pet_form')
... # check is_valid(), render when no POST data is present, etc.
The point is the addition works perfectly, storing each instance in the corresponding database table, etc. I use jquery.formset-1.2.js to manage the dynamical addition-deletion of forms in the "add.html".
But I later want to edit the stored info through a view, i.e., load the data from the object I pass in the request, and render the formsets with the data obtained from the database (if there are 3 pets related to the person being editted, display 3 form instances of "Pet" with their value displayed).
I would like to also add new Pets and remove existing ones, as well as changing existing field values.
I have tried with querysets in the FormSet creation, but it doesn't display anything.
Any idea how to ease this issue? Maybe using an app for an easier formset management?
Thank you
I'm not sure if I understand your problem correctly. If you want to display all Pets that belong to the Person:
def show_pets(request, person_id=None):
person = get_object_or_404(Person.objects.select_related(), id=person_id)
if request.method == 'POST':
person_form = PersonForm(request.POST, instance=person)
pet_formset = PetFormSet(request.POST, instance=person)
# Rest of your code here
else:
person_form = PersonForm(instance=person)
pet_formset = PetFormSet(instance=person)
return render_to_response('your_template.html', {'person_form': person_form,
'pet_formset': pet_formset)})
Then you just need to render both forms in your template and add add and delete functionality

Django "Enter a list of values" form error when rendering a ManyToManyField as a Textarea

I'm trying to learn Django and I've ran into some confusing points. I'm currently having trouble creating a movie using a form. The idea of the form is to give the user any field he'd like to fill out. Any field that the user fills out will be updated in its respective sql table (empty fields will be ignored). But, the form keeps giving me the error "Enter a list of values" when I submit the form. To address this, I thought stuffing the data from the form into a list and then returning that list would solve this.
The first idea was to override the clean() in my ModelForm. However, because the form fails the is_valid() check in my views, the cleaned_data variable in clean() doesn't contain anything. Next, I tried to override the to_python(). However, to_python() doesn't seem to be called.
If I put __metaclass__ = models.SubfieldBase in the respective model, I receive the runtime error
"TypeError: Error when calling the
metaclass bases
metaclass conflict: the metaclass of a derived class must be a
(non-strict) subclass of the
metaclasses of all its bases"
My approach doesn't seem to work. I'm not sure how to get around the 'Enter a list of values" error! Any advice?
Here is the relevant code (updated):
models.py
""" Idea:
A movie consists of many equipments, actors, and lighting techniques. It also has a rank for the particular movie, as well as a title.
A Theater consists of many movies.
A nation consists of many theaters.
"""
from django.db import models
from django.contrib.auth.models import User
class EquipmentModel(models.Model):
equip = models.CharField(max_length=20)
# user = models.ForeignKey(User)
class ActorModel(models.Model):
actor = models.CharField(max_length=20)
# user = models.ForeignKey(User)
class LightModel(models.Model):
light = models.CharField(max_length=20)
# user = models.ForeignKey(User)
class MovieModel(models.Model):
# __metaclass__ = models.SubfieldBase
rank = models.DecimalField(max_digits=5000, decimal_places=3)
title = models.CharField(max_length=20)
equipments = models.ManyToManyField(EquipmentModel, blank=True, null=True)
actors = models.ManyToManyField(ActorModel, blank=True, null=True)
lights = models.ManyToManyField(LightModel, blank=True, null=True)
class TheaterModel(models.Model):
movies = models.ForeignKey(MovieModel)
class NationModel(models.Model):
theaters = models.ForeignKey(TheaterModel)
=====================================
forms.py
"""
These Modelforms tie in the models from models.py
Users will be able to write to any of the fields in MovieModel when creating a movie.
Users may leave any field blank (empty fields should be ignored, ie: no updates to database).
"""
from django import forms
from models import MovieModel
from django.forms.widgets import Textarea
class MovieModelForm(forms.ModelForm):
def __init__(self, *args, **kwargs):
super(MovieModelForm, self).__init__(*args, **kwargs)
self.fields["actors"].widget = Textarea()
self.fields["equipments"].widget = Textarea()
self.fields["lights"].widget = Textarea()
def clean_actors(self):
data = self.cleaned_data.get('actors')
print 'cleaning actors'
return [data]
class Meta:
model = MovieModel
=============================================
views.py
""" This will display the form used to create a MovieModel """
from django.shortcuts import render_to_response
from django.template import RequestContext
from forms import MovieModelForm
def add_movie(request):
if request.method == "POST":
form = MovieModelForm(request.POST)
if form.is_valid():
new_moviemodel = form.save()
return HttpResponseRedirect('/data/')
else:
form = MovieModelForm()
return render_to_response('add_movie_form.html', {form:form,}, context_instance=RequestContext(request))
The probable problem is that the list of values provided in the text area can not be normalized into a list of Models.
See the ModelMultipleChoiceField documentation.
The field is expecting a list of valid IDs, but is probably receiving a list of text values, which django has no way of converting to the actual model instances. The to_python will be failing within the form field, not within the form itself. Therefore, the values never even reach the form.
Is there something wrong with using the built in ModelMultipleChoiceField? It will provide the easiest approach, but will require your users to scan a list of available actors (I'm using the actors field as the example here).
Before I show an example of how I'd attempt to do what you want, I must ask; how do you want to handle actors that have been entered that don't yet exist in your database? You can either create them if they exist, or you can fail. You need to make a decision on this.
# only showing the actor example, you can use something like this for other fields too
class MovieModelForm(forms.ModelForm):
actors_list = fields.CharField(required=False, widget=forms.Textarea())
class Meta:
model = MovieModel
exclude = ('actors',)
def clean_actors_list(self):
data = self.cleaned_data
actors_list = data.get('actors_list', None)
if actors_list is not None:
for actor_name in actors_list.split(','):
try:
actor = Actor.objects.get(actor=actor_name)
except Actor.DoesNotExist:
if FAIL_ON_NOT_EXIST: # decide if you want this behaviour or to create it
raise forms.ValidationError('Actor %s does not exist' % actor_name)
else: # create it if it doesnt exist
Actor(actor=actor_name).save()
return actors_list
def save(self, commit=True):
mminstance = super(MovieModelForm, self).save(commit=commit)
actors_list = self.cleaned_data.get('actors_list', None)
if actors_list is not None:
for actor_name in actors_list.split(","):
actor = Actor.objects.get(actor=actor_name)
mminstance.actors.add(actor)
mminstance.save()
return mminstance
The above is all untested code, but something approaching this should work if you really want to use a Textarea for a ModelMultipleChoiceField. If you do go down this route, and you discover errors in my code above, please either edit my answer, or provide a comment so I can. Good luck.
Edit:
The other option is to create a field that understands a comma separated list of values, but behaves in a similar way to ModelMultipleChoiceField. Looking at the source code for ModelMultipleChoiceField, it inhertis from ModelChoiceField, which DOES allow you to define which value on the model is used to normalize.
## removed code because it's no longer relevant. See Last Edit ##
Edit:
Wow, I really should have checked the django trac to see if this was already fixed. It is. See the following ticket for information. Essentially, they've done the same thing I have. They've made ModelMutipleChoiceField respect the to_field_name argument. This is only applicable for django 1.3!
The problem is, the regular ModelMultipleChoiceField will see the comma separated string, and fail because it isn't a List or Tuple. So, our job becomes a little more difficult, because we have to change the string to a list or tuple, before the regular clean method can run.
class ModelCommaSeparatedChoiceField(ModelMultipleChoiceField):
widget = Textarea
def clean(self, value):
if value is not None:
value = [item.strip() for item in value.split(",")] # remove padding
return super(ModelCommaSeparatedChoiceField, self).clean(value)
So, now your form should look like this:
class MovieModelForm(forms.ModelForm):
actors = ModelCommaSeparatedChoiceField(
required=False,
queryset=Actor.objects.filter(),
to_field_name='actor')
equipments = ModelCommaSeparatedChoiceField(
required=False,
queryset=Equipment.objects.filter(),
to_field_name='equip')
lights = ModelCommaSeparatedChoiceField(
required=False,
queryset=Light.objects.filter(),
to_field_name='light')
class Meta:
model = MovieModel
to_python AFAIK is a method for fields, not forms.
clean() occurs after individual field cleaning, so your ModelMultipleChoiceFields clean() methods are raising validation errors and thus cleaned_data does not contain anything.
You haven't provided examples for what kind of data is being input, but the answer lies in form field cleaning.
http://docs.djangoproject.com/en/dev/ref/forms/validation/#cleaning-a-specific-field-attribute
You need to write validation specific to that field that either returns the correct data in the format your field is expecting, or raises a ValidationError so your view can re-render the form with error messages.
update: You're probably missing the ModelForm __init__ -- see if that fixes it.
class MovieModelForm(forms.ModelForm):
def __init__(self, *args, **kwargs):
super(MovieModelForm, self).__init__(*args, **kwargs)
self.fields["actors"].widget = Textarea()
def clean_actors(self):
data = self.cleaned_data.get('actors')
# validate incoming data. Convert the raw incoming string
# to a list of ids this field is expecting.
# if invalid, raise forms.ValidationError("Error MSG")
return data.split(',') # just an example if data was '1,3,4'

django manytomany validation

Please see the code below. Basically, when the user creates an object of this class, they need to specify the value_type. If value_type==2 (percentage), then percentage_calculated_on (which is a CheckboxSelectMultiple on the form/template side needs to have one or more items checked. The model validation isn't allowing me to validate like I'm trying to -- it basically throws an exception that tells me that the instance needs to have a primary key value before a many-to-many relationship can be used. But I need to first validate the object before saving it. I have tried this validation on the form (modelform) side (using the form's clean method), but the same thing happens there too.
How do I go about achieving this validation?
INHERENT_TYPE_CHOICES = ((1, 'Payable'), (2, 'Deductible'))
VALUE_TYPE_CHOICES = ((1, 'Amount'), (2, 'Percentage'))
class Payable(models.Model):
name = models.CharField()
short_name = models.CharField()
inherent_type = models.PositiveSmallIntegerField(choices=INHERENT_TYPE_CHOICES)
value = models.DecimalField(max_digits=12,decimal_places=2)
value_type = models.PositiveSmallIntegerField(choices=VALUE_TYPE_CHOICES)
percentage_calculated_on = models.ManyToManyField('self', symmetrical=False)
def clean(self):
from django.core.exceptions import ValidationError
if self.value_type == 2 and not self.percentage_calculated_on:
raise ValidationError("If this is a percentage, please specify on what payables/deductibles this percentage should be calculated on.")
I tested out your code in one of my projects' admin app. I was able to perform the validation you required by using a custom ModelForm. See below.
# forms.py
class MyPayableForm(forms.ModelForm):
class Meta:
model = Payable
def clean(self):
super(MyPayableForm, self).clean() # Thanks, #chefsmart
value_type = self.cleaned_data.get('value_type', None)
percentage_calculated_on = self.cleaned_data.get(
'percentage_calculated_on', None)
if value_type == 2 and not percentage_calculated_on:
message = "Please specify on what payables/deductibles ..."
raise forms.ValidationError(message)
return self.cleaned_data
# admin.py
class PayableAdmin(admin.ModelAdmin):
form = MyPayableForm
admin.site.register(Payable, PayableAdmin)
The Admin app uses the SelectMultiple widget (rather than CheckboxSelectMultiple as you do) to represent many to many relationships. I believe this shouldn't matter though.