Django set default form values

Question

I have a Model as follows:

class TankJournal(models.Model):
    user = models.ForeignKey(User)
    tank = models.ForeignKey(TankProfile)
    ts = models.IntegerField(max_length=15)
    title = models.CharField(max_length=50)
    body = models.TextField()

I also have a model form for the above model as follows:

class JournalForm(ModelForm):
    tank = forms.IntegerField(widget=forms.HiddenInput()) 

    class Meta:
        model = TankJournal
        exclude = ('user','ts')

I want to know how to set the default value for that tank hidden field. Here is my function to show/save the form so far:

def addJournal(request, id=0):
    if not request.user.is_authenticated():
        return HttpResponseRedirect('/')

    # checking if they own the tank
    from django.contrib.auth.models import User
    user = User.objects.get(pk=request.session['id'])

    if request.method == 'POST':
        form = JournalForm(request.POST)
        if form.is_valid():
            obj = form.save(commit=False)

            # setting the user and ts
            from time import time
            obj.ts = int(time())
            obj.user = user

            obj.tank = TankProfile.objects.get(pk=form.cleaned_data['tank_id'])

            # saving the test
            obj.save()

    else:
        form = JournalForm()

    try:
        tank = TankProfile.objects.get(user=user, id=id)
    except TankProfile.DoesNotExist:
        return HttpResponseRedirect('/error/')

Flimm · Accepted Answer · 2025-03-05 14:00:11Z

520

You can use Form.initial.

You have two options either populate the value when calling form constructor:

form = JournalForm(initial={'tank': 123})

or set the value in the form definition:

tank = forms.IntegerField(widget=forms.HiddenInput(), initial=123)

edited Mar 5 at 14:00

Flimm

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answered Mar 2, 2009 at 22:29

Sergey Golovchenko

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11 Comments

Richard J Foster Over a year ago

@bharal It's magic. ;-) (Or rather, Django form constructors understand the special "initial" variable and iterate through its contents without you needing to do anything extra). Personally, I prefer to specify default values in the form definition and only use the initial=... mechanism if the desired default is a dynamic value (e.g. something entered by a user, or based on their login, geographical location, etc.)

clime Over a year ago

initial is not default. The initial value does not apply if the form has been bound:(.

tutuca Over a year ago

I swear there was a default keyword argument on the Field constructor... I can't find the documentation for it now... EDIT: I mistook it for the ModelField reference. FormFields have no defaul argument

Keshav Agrawal Over a year ago

Commenting here to mention another usecase where this solution of initial param will help: While sending a registration link to someone if you want to prepopulate the email/id or any other credential on the registration form then in that case you can't write that in the model itself as its dynamic rather you need to call the constructor with initial param as mentioned by @umnik700. Works great!

GDorn Over a year ago

@Phlip: Don't override View.get_form to set initial data. Any CBV with a FormMixin (basically all CBVs that create or edit data) can either use a class-level initial variable (for unchanging defaults) or you can override FormMixin.get_initial() to return a dict of initial values to be passed to the form's constructor (for dynamic defaults.)

|

Andreas Zwerger · Accepted Answer · 2018-03-30 13:39:42Z

62

Other solution: Set initial after creating the form:

form.fields['tank'].initial = 123

answered Mar 30, 2018 at 13:39

Andreas Zwerger

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1 Comment

Dr Phil Over a year ago

This is the solution I needed. I have a form with default initial values, but sometimes the user comes back to a page to edit something. In that case the initial values are the previously saved values (dynamic).

smunk · Accepted Answer · 2019-06-06 21:01:48Z

26

If you are creating modelform from POST values initial can be assigned this way:

form = SomeModelForm(request.POST, initial={"option": "10"})

https://docs.djangoproject.com/en/1.10/topics/forms/modelforms/#providing-initial-values

edited Jun 6, 2019 at 21:01

smunk

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answered Feb 12, 2015 at 18:18

quux

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2 Comments

smido Over a year ago

That or None part is really not needed.

Bobort Over a year ago

@smido, yes the or None part is needed. If the request is a GET request, request.POST will be an empty dictionary which is treated differently than None in the Form init method. Please review Django documentation.

Flimm · Accepted Answer · 2021-05-19 17:12:17Z

23

As explained in Django docs, initial is not default.

The initial value of a field is intended to be displayed in an HTML . But if the user delete this value, and finally send back a blank value for this field, the initial value is lost. So you do not obtain what is expected by a default behaviour.
The default behaviour is : the value that validation process will take if data argument do not contain any value for the field.

To implement that, a straightforward way is to combine initial and clean_<field>():

class JournalForm(ModelForm):
    tank = forms.IntegerField(widget=forms.HiddenInput(), initial=123) 

    (...)

    def clean_tank(self):
        if not self['tank'].html_name in self.data:
            return self.fields['tank'].initial
        return self.cleaned_data['tank']

edited May 19, 2021 at 17:12

Flimm

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answered May 13, 2020 at 11:51

Timothé Delion

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Comments

Rafael Ortega · Accepted Answer · 2018-04-03 00:17:03Z

21

I had this other solution (I'm posting it in case someone else as me is using the following method from the model):

class onlyUserIsActiveField(forms.ModelForm):
    def __init__(self, *args, **kwargs):
        super(onlyUserIsActiveField, self).__init__(*args, **kwargs)
        self.fields['is_active'].initial = False

    class Meta:
        model = User
        fields = ['is_active']
        labels = {'is_active': 'Is Active'}
        widgets = {
            'is_active': forms.CheckboxInput( attrs={
                            'class':          'form-control bootstrap-switch',
                            'data-size':      'mini',
                            'data-on-color':  'success',
                            'data-on-text':   'Active',
                            'data-off-color': 'danger',
                            'data-off-text':  'Inactive',
                            'name':           'is_active',

            })
        }

The initial is definded on the __init__ function as self.fields['is_active'].initial = False

answered Apr 3, 2018 at 0:17

Rafael Ortega

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2 Comments

hehe Over a year ago

thanks! this works! I tried the method in the post above by adding initial while creating the form, somehow it did not work for me.

hehe Over a year ago

Actually there is an easier way: Just set default value in models. For example: alpha=models.FloatField(max_length=150, verbose_name="Enter an alpha level", default=0.05)

Yahya mlaouhi · Accepted Answer · 2022-12-24 13:40:02Z

3

If you want to add initial value and post other value you have to add the following :

or None after request.POST

form = JournalForm(request.POST or None,initial={'tank': 123})

If you want to add files or images also

form = JournalForm(request.POST or None,request.FILES or None,initial={'tank': 123})

edited Dec 24, 2022 at 13:40

user9517769

answered Dec 13, 2022 at 16:15

Yahya mlaouhi

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Comments

Valerii Boldakov · Accepted Answer · 2020-03-06 08:54:00Z

1

I hope this can help you:

form.instance.updatedby = form.cleaned_data['updatedby'] = request.user.id

edited Mar 6, 2020 at 8:54

Valerii Boldakov

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answered Mar 6, 2020 at 8:23

Code47

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Comments

AvMuni · Accepted Answer · 2023-09-15 08:08:29Z

Posting another solution i came up with:

template.html:

<form id="myForm" method="post">
{% csrf_token %}
{{ form.media }}
{{ form.well_id.label_tag }}
{{ form.well_id }}
{{ form.tube_id.label_tag }}
{{ form.tube_id }}
<button type="submit" >Run Analysis</button>
</form>

<script type="text/javascript">

    $(document).ready(function() {
        $("#id_well_id").select2();
        $("#id_tube_id").select2();
        
        {% if request.method == 'GET' %} // Because id_tube_id is a 'required' form field, we need to initialize a null parameter to show the placeholder.
        $("#id_tube_id").val(null);
        $("#id_tube_id").trigger('change');
        {% endif %}
    });
</script>

The reasoning behind using this method and not the pure python based methods posted above was that I had set the tube_id field to be a required form field but not the well_id field. Apparently, if you assign a field to be required, it is being prefilled with the first value in your list of choices, unless specified otherwise by an initial value. But in my case, i didn't want an initial value - i just wanted the initial value to be None. Django can assign a choice as an initial value only if it allready exists in your list of choices, so if you would assign None as an initial value, it would just show the first item on the list.

The solution is therefore to assign an initial value through javascript (in my case, i needed it to happen only if request.method == 'GET').

xin.chen · Accepted Answer · 2021-03-25 10:47:03Z

0

I also encountered the need to set default values in the form during development. My solution is

initial={"":""}
form=ArticleModel(request.POST)
if form.has_changed():
    data = {i: form.cleaned_data[i] for i in form.changed_data}
    data.update({key: val for key, val in init_praram.items() if key not in form.changed_data})

use form.has_changed ,if form.fields is required you can use this method

answered Mar 25, 2021 at 10:47

xin.chen

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Comments

AnonymousUser · Accepted Answer · 2022-07-26 06:01:01Z

How I added the initial to the form: I read @Sergey Golovchenko answer.

So I just added it to the form in if request.method == 'POST':. But that's not where you place it, if you want to see what value it got before posting the form. You need to put it in the form where the else is.

Example here from views.py

def myForm(request):
    kontext = {}

    if request.method == 'POST':
        # You might want to use clean_data instead of initial here. I found something on a stack overflow question, and you add clean data to the Forms.py, if you want to change the post data. https://stackoverflow.com/questions/36711229/django-forms-clean-data
        form = myModelForm(request.POST, initial={'user': request.user})
        if form.is_valid():
            form.save()
            return redirect('/')
    else:
        # you need to put initial here, if you want to see the value before you post it
        form = myModelForm(initial={'user': request.user})
    kontext['form'] = form
    return render(request, 'app1/my_form.html', kontext)

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