Suppose I have the following model
class MyChoiceModel(models.Model):
mychoices = (('ChoiceA', 'ChoiceA'), ('ChoiceB', 'ChoiceB'))
and the following ModelForm
class MyChoiceModelForm(forms.ModelForm):
#...
class Meta:
model = MyChoiceModel
fields = ('mychoices', )
Now, the user can select all types of choices (ChoiceA and ChoiceB).
What I want now is that certain choice values won't be displayed.
How can I filter the available choices from mychoices such that for example only ChoiceA would be selectable by the user and - under other circumstances - only ChoiceB?
There are numerous ways to do this: here is a way that i have
def CustomChoiceList():
# return custom choices
class MyChoiceModelForm(forms.ModelForm):
class Meta:
widgets = { 'mychoices': CustomChoiceList() }
if you need more control, or access to the model look at creating a forms.ModelChoiceField)
eg:
class CustomChoices(forms.ModelChoiceField):
def label_from_instance(self, obj):
# return some obj.title, or whatever in your object as the label to show
then in the ModelForm
mychoices = CustomChoices(required=True, queryset=YourModelYouWant.objects.filter(...))
Related
I'd like to add some info to a model field to use at form rendering time. My real model has about 15 values of varying field types (adding and removing as I dev), and it does almost everything I need, so I'd rather not create custom model fields for all of them.
I'd like to do something like this:
from django.db import models
class MyModel(models.Model):
cost = models.DecimalField(max_digits=5,
decimal_places=2,
custom_info= {'glyph': 'glyphicon glyphicon-usd' }
)
And then in my form template use that glyph much like I'd use a verbose_name or help_text.
Something I learned from a post just the other day. Will defining the custom information on the form instead of the model work?
When you define formfield_callback on a forms.ModelForm it will iterate over the form fields and you can manipulate them. This comes in handy when you need to add a css class to widgets and don't want to explicitly override the field. Now you only need to put formfield_callback = modify_form_field on any forms.ModelForm where you want the custom_info to show up.
from django.db import models
def add_glyphicons(model_field):
form_field = model_field.formfield()
if isinstance(model_field, models.IntegerField):
form_field.custom_info = {'glyph': 'glyphicon glyphicon-usd'}
elif isinstance(model_field, models.CharField):
form_field.custom_info = {'glyph': 'glyphicon glyphicon-yen'}
return form_field
class MyModel(models.Model):
formfield_callback = add_glyphicons
class Meta:
model = MyModel
class MyOtherModel(models.Model):
formfield_callback = add_glyphicons
class Meta:
model = MyOtherModel
I use Django Model Form:
class Fruit(models.Model):
name = models.CharField(max_length=40)
class Box(models.Model):
user = models.ForeignKey(User)
name = models.CharField(max_length=199)
fruit = models.ManyToManyField(Fruit)
and forms.py:
class BoxModelForm(ModelForm):
class Meta:
model = Box
I have default django ManyToMany widget in form:
http://nov.imghost.us/ly5M.png
How can I change this to input (text type) and if I type into this input:
apple,banana,lemon - comma separated
this Fruit will be created?
As stated here in the documentation :https://docs.djangoproject.com/en/dev/topics/forms/modelforms/#overriding-the-default-fields
You can add a widgets attribute to the Meta of your Modelform to change the default widgets used in the form.
In your case it would be something like this :
class BoxModelForm(ModelForm):
class Meta:
model = Box
widgets = {
'fruit': TheWidgetYouWantToUse(),
}
But actually for the behavior you want to achieve, you could proceed another way.
You should add an extra text field, and write the addition/removal of fruits in the save step, while checking the validity of the differents tags in the clean step.
class BoxModelForm(ModelForm):
fruit_selector = forms.TextField(
max_length=255,
tag = 'Whatever'
)
class Meta:
model = Box
fields = ['user','name']
def clean_fruit_selector(self):
data = self.cleaned_data['fruit_selector']
# Check that data are corrects ie the string is correctly formatted
# If not raise validation error
....
fruit_tags = data.split(",")
#Check that all tags are fruit or raise a validation error
...
return data #or only the list of correct tags
def save(self, commit=True):
instance = super(MyForm, self).save(commit=False)
# Compare the list of tags fruit_tags with self.instance.fruit.all()
....
# Take the right actions
if commit:
instance.save()
return instance
Look into this page for more details on how to change the field validation https://docs.djangoproject.com/en/dev/ref/forms/validation/
This is just a schematic.
django-taggit is a perfect app for this use case.
Define your models like this:
from taggit.managers import TaggableManager
from taggit.models import TagBase, GenericTaggedItemBase
class Fruit(TagBase):
class Meta:
verbose_name = "Fruit"
verbose_name_plural = "Fruits"
class TaggedFruit(GenericTaggedItemBase):
tag = models.ForeignKey(Fruit,
related_name="%(app_label)s_%(class)s_items")
class Box(models.Model):
name = models.CharField(max_length=199)
fruits = TaggableManager(through=TaggedFruit)
Then create basic model form:
class BoxModelForm(ModelForm):
class Meta:
model = Box
And that's it! You can now add fruit tags into your box, separated by comma. In case the fruit doesn't exist, it will be added into Fruit table. Read the docs for more details on how to use django-taggit.
You can use it together with jquery based Selectize.js.
I have a Django model with a ManyToManyField.
1) When adding a new instance of this model via admin view, I would like to not see the M2M field at all.
2) When editing an existing instance I would like to be able to select multiple options for the M2M field, but display only a subset of the M2M options, depending on another field in the model. Because of the dependence on another field's actual value, I can't just use formfield_for_manytomany
I can do both of the things using a custom ModelForm, but I can't reliably tell whether that form is being used to edit an existing model instance, or if it's being used to create a new instance. Even MyModel.objects.filter(pk=self.instance.pk).exists() in the custom ModelForm doesn't cut it. How can I accomplish this, or just tell whether the form is being displayed in an "add" or an "edit" context?
EDIT: my relevant code is as follows:
models.py
class LimitedClassForm(forms.ModelForm):
def __init__(self, *args, **kwargs):
super(LimitedClassForm, self).__init__(*args, **kwargs)
if not self.instance._adding:
# Edit form
clas = self.instance
sheets_in_course = Sheet.objects.filter(course__pk=clas.course.pk)
self.Meta.exclude = ['course']
widget = self.fields['active_sheets'].widget
sheet_choices = []
for sheet in sheets_in_course:
sheet_choices.append((sheet.id, sheet.name))
widget.choices = sheet_choices
else:
# Add form
self.Meta.exclude = ['active_sheets']
class Meta:
exclude = []
admin.py
class ClassAdmin(admin.ModelAdmin):
formfield_overrides = {models.ManyToManyField: {
'widget': CheckboxSelectMultiple}, }
form = LimitedClassForm
admin.site.register(Class, ClassAdmin)
models.py
class Course(models.Model):
name = models.CharField(max_length=255)
class Sheet(models.Model):
name = models.CharField(max_length=255)
course = models.ForeignKey(Course)
file = models.FileField(upload_to=getSheetLocation)
class Class(models.model):
name = models.CharField(max_length=255)
course = models.ForeignKey(Course)
active_sheets = models.ManyToManyField(Sheet)
You can see that both Sheets and Classes have course fields. You shouldn't be able to put a sheet into active_sheets if the sheet's course doesn't match the class's course.
My model form inherit from subsystem form.
I want to limit choices for the user in the form. (specially the name)
I know I have to use widgets. But It doesn't work.
I have to use SubsytemForm.
SUBSYSTEM_CHOICES = (a1,a2,a3)
class Subsystem(models.Model):
name = models.CharField("Name", max_length=20)
class SubsytemForm(forms.ModelForm):
class Meta:
model = Subsystem
widgets = {
'name': ChoiceField(widget=RadioSelect, choices=SUBSYSTEM_CHOICES)
}
From django model forms documentation:
If you explicitly instantiate a form field like this, Django assumes
that you want to completely define its behavior; therefore, default
attributes (such as max_length or required) are not drawn from the
corresponding model. If you want to maintain the behavior specified in
the model, you must set the relevant arguments explicitly when
declaring the form field.
You can try with:
class SubsytemForm(forms.ModelForm):
name = forms.ChoiceField(widget=RadioSelect, choices= choices )
class Meta:
model = Subsystem
Also you can
class SubsytemForm(forms.ModelForm):
class Meta:
model = Subsystem
def __init__(self, *args, **kwargs):
self.name_choices = kwargs.pop('name_choices', None)
super(SubsytemForm,self).__init__(*args,**kwargs)
self.fields['name'].queryset= self.name_choices
and send name_choices as parameter in SubsytemForm creation. Remember that choices should be a query set.
Also, you should read How do I filter ForeignKey choices in a Django ModelForm?
SUBSYSTEM_CHOICES is not a valid value for the choices attribute because it has no key/value pairs. You need something like:
SUBSYSTEM_CHOICES = (
(a1, 'a1 Display'),
(a2, 'a2 Display'),
(a3, 'a3 Display'),
)
I need to make a form, which have 1 select and 1 text input. Select must be taken from database.
model looks like this:
class Province(models.Model):
name = models.CharField(max_length=30)
slug = models.SlugField(max_length=30)
def __unicode__(self):
return self.name
It's rows to this are added only by admin, but all users can see it in forms.
I want to make a ModelForm from that. I made something like this:
class ProvinceForm(ModelForm):
class Meta:
CHOICES = Province.objects.all()
model = Province
fields = ('name',)
widgets = {
'name': Select(choices=CHOICES),
}
but it doesn't work. The select tag is not displayed in html. What did I wrong?
UPDATE:
This solution works as I wanto it to work:
class ProvinceForm(ModelForm):
def __init__(self, *args, **kwargs):
super(ProvinceForm, self).__init__(*args, **kwargs)
user_provinces = UserProvince.objects.select_related().filter(user__exact=self.instance.id).values_list('province')
self.fields['name'].queryset = Province.objects.exclude(id__in=user_provinces).only('id', 'name')
name = forms.ModelChoiceField(queryset=None, empty_label=None)
class Meta:
model = Province
fields = ('name',)
Read Maersu's answer for the method that just "works".
If you want to customize, know that choices takes a list of tuples, ie (('val','display_val'), (...), ...)
Choices doc:
An iterable (e.g., a list or tuple) of
2-tuples to use as choices for this
field.
from django.forms.widgets import Select
class ProvinceForm(ModelForm):
class Meta:
CHOICES = Province.objects.all()
model = Province
fields = ('name',)
widgets = {
'name': Select(choices=( (x.id, x.name) for x in CHOICES )),
}
ModelForm covers all your needs (Also check the Conversion List)
Model:
class UserProvince(models.Model):
user = models.ForeignKey(User)
province = models.ForeignKey(Province)
Form:
class ProvinceForm(ModelForm):
class Meta:
model = UserProvince
fields = ('province',)
View:
if request.POST:
form = ProvinceForm(request.POST)
if form.is_valid():
obj = form.save(commit=True)
obj.user = request.user
obj.save()
else:
form = ProvinceForm()
If you need to use a query for your choices then you'll need to overwrite the __init__ method of your form.
Your first guess would probably be to save it as a variable before your list of fields but you shouldn't do that since you want your queries to be updated every time the form is accessed. You see, once you run the server the choices are generated and won't change until your next server restart. This means your query will be executed only once and forever hold your peace.
# Don't do this
class MyForm(forms.Form):
# Making the query
MYQUERY = User.objects.values_list('id', 'last_name')
myfield = forms.ChoiceField(choices=(*MYQUERY,))
class Meta:
fields = ('myfield',)
The solution here is to make use of the __init__ method which is called on every form load. This way the result of your query will always be updated.
# Do this instead
class MyForm(forms.Form):
class Meta:
fields = ('myfield',)
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
# Make the query here
MYQUERY = User.objects.values_list('id', 'last_name')
self.fields['myfield'] = forms.ChoiceField(choices=(*MYQUERY,))
Querying your database can be heavy if you have a lot of users so in the future I suggest some caching might be useful.
the two solutions given by maersu and Yuji 'Tomita' Tomita perfectly works, but there are cases when one cannot use ModelForm (django3 link), ie the form needs sources from several models / is a subclass of a ModelForm class and one want to add an extra field with choices from another model, etc.
ChoiceField is to my point of view a more generic way to answer the need.
The example below provides two choice fields from two models and a blank choice for each :
class MixedForm(forms.Form):
speaker = forms.ChoiceField(choices=([['','-'*10]]+[[x.id, x.__str__()] for x in Speakers.objects.all()]))
event = forms.ChoiceField(choices=( [['','-'*10]]+[[x.id, x.__str__()] for x in Events.objects.all()]))
If one does not need a blank field, or one does not need to use a function for the choice label but the model fields or a property it can be a bit more elegant, as eugene suggested :
class MixedForm(forms.Form):
speaker = forms.ChoiceField(choices=((x.id, x.__str__()) for x in Speakers.objects.all()))
event = forms.ChoiceField(choices=(Events.objects.values_list('id', 'name')))
using values_list() and a blank field :
event = forms.ChoiceField(choices=([['','-------------']] + list(Events.objects.values_list('id', 'name'))))
as a subclass of a ModelForm, using the one of the robos85 question :
class MixedForm(ProvinceForm):
speaker = ...