I'm working on something like an online store. I'm making a form in which the customer buys an item, and she can choose how many of these item she would like to buy. But, on every item that she buys she needs to choose what its color would be. So there's a non-constant number of fields: If the customer buys 3 items, she should get 3 <select> boxes for choosing a color, if she buys 7 items, she should get 7 such <select> boxes.
I'll make the HTML form fields appear and disappear using JavaScript. But how do I deal with this on my Django form class? I see that form fields are class attributes, so I don't know how to deal with the fact that some form instance should have 3 color fields and some 7.
Any clue?
Jacob Kaplan-Moss has an extensive writeup on dynamic form fields:
http://jacobian.org/writing/dynamic-form-generation/
Essentially, you add more items to the form's self.fields dictionary during instantiation.
Here's another option: how about a formset?
Since your fields are all the same, that's precisely what formsets are used for.
The django admin uses FormSets + a bit of javascript to add arbitrary length inlines.
class ColorForm(forms.Form):
color = forms.ChoiceField(choices=(('blue', 'Blue'), ('red', 'Red')))
ColorFormSet = formset_factory(ColorForm, extra=0)
# we'll dynamically create the elements, no need for any forms
def myview(request):
if request.method == "POST":
formset = ColorFormSet(request.POST)
for form in formset.forms:
print "You've picked {0}".format(form.cleaned_data['color'])
else:
formset = ColorFormSet()
return render(request, 'template', {'formset': formset}))
JavaScript
<script>
$(function() {
// this is on click event just to demo.
// You would probably run this at page load or quantity change.
$("#generate_forms").click(function() {
// update total form count
quantity = $("[name=quantity]").val();
$("[name=form-TOTAL_FORMS]").val(quantity);
// copy the template and replace prefixes with the correct index
for (i=0;i<quantity;i++) {
// Note: Must use global replace here
html = $("#form_template").clone().html().replace(/__prefix_/g', i);
$("#forms").append(html);
};
})
})
</script>
Template
<form method="post">
{{ formset.management_form }}
<div style="display:none;" id="form_template">
{{ formset.empty_form.as_p }}
</div><!-- stores empty form for javascript -->
<div id="forms"></div><!-- where the generated forms go -->
</form>
<input type="text" name="quantity" value="6" />
<input type="submit" id="generate_forms" value="Generate Forms" />
you can do it like
def __init__(self, n, *args, **kwargs):
super(your_form, self).__init__(*args, **kwargs)
for i in range(0, n):
self.fields["field_name %d" % i] = forms.CharField()
and when you create form instance, you just do
forms = your_form(n)
it's just the basic idea, you can change the code to whatever your want. :D
The way I would do it is the following:
Create an "empty" class that inherits from froms.Form, like this:
class ItemsForm(forms.Form):
pass
Construct a dictionary of forms objects being the actual forms, whose composition would be dependent on the context (e.g. you can import them from an external module). For example:
new_fields = {
'milk' : forms.IntegerField(),
'butter': forms.IntegerField(),
'honey' : forms.IntegerField(),
'eggs' : forms.IntegerField()}
In views, you can use python native "type" function to dynamically generate a Form class with variable number of fields.
DynamicItemsForm = type('DynamicItemsForm', (ItemsForm,), new_fields)
Pass the content to the form and render it in the template:
Form = DynamicItemsForm(content)
context['my_form'] = Form
return render(request, "demo/dynamic.html", context)
The "content" is a dictionary of field values (e.g. even request.POST would do).
You can see my whole example explained here.
Another approach: Rather than breaking the normal field initialization flow, we can override fields with a mixin, return an OrderedDict of dynamic fields in generate_dynamic_fields which will be added whenever its set.
from collections import OrderedDict
class DynamicFormMixin:
_fields: OrderedDict = None
#property
def fields(self):
return self._fields
#fields.setter
def fields(self, value):
self._fields = value
self._fields.update(self.generate_dynamic_fields())
def generate_dynamic_fields(self):
return OrderedDict()
A simple example:
class ExampleForm(DynamicFormMixin, forms.Form):
instance = None
def __init__(self, instance = None, data=None, files=None, auto_id='id_%s', prefix=None, initial=None,
error_class=ErrorList, label_suffix=None, empty_permitted=False, field_order=None,
use_required_attribute=None, renderer=None):
self.instance = instance
super().__init__(data, files, auto_id, prefix, initial, error_class, label_suffix, empty_permitted, field_order,
use_required_attribute, renderer)
def generate_dynamic_fields(self):
dynamic_fields = OrderedDict()
instance = self.instance
dynamic_fields["dynamic_choices"] = forms.ChoiceField(label=_("Number of choices"),
choices=[(str(x), str(x)) for x in range(1, instance.number_of_choices + 1)],
initial=instance.initial_choice)
return dynamic_fields
A form will be spitting out an unknown number of questions to be answered. each question contains a prompt, a value field, and a unit field. The form is built at runtime in the formclass's init method.
edit: each questions receives a unique prompt to be used as a label, as well as a unique list of units for the select element.
this seems a case perfect for iterable form fieldsets, which could be easily styled. but since fieldsets - such as those in django-form-utils are defined as tuples, they are immutable... and I can't find a way to define them at runtime. is this possible, or perhaps another solution?
Edit:
formsets with initial_data is not the answer - initial_data merely enables the setting of default values for the form fields in a formset. a list of items can't be sent to the choicefield constructor by way of initial_data.
...unless I'm wrong.
Check out formsets. You should be able to pass in the data for each of the N questions as initial data. Something along these lines:
question_data = []
for question in your_question_list:
question_data.append({'prompt': question.prompt,
'value': question.value,
'units': question.units})
QuestionFormSet = formset_factory(QuestionForm, extra=2)
formset = QuestionFormSet(initial=question_data)
Old question but I am running into a similar problem. The closest thing that I have found so far is this snippet based of a post that Malcom did a couple years ago now.
http://djangosnippets.org/snippets/1955/
The original snippet did not address the template side and splitting them up into fieldsets, but adding each form to its own fieldset should accomplish that.
forms.py
from django.forms.formsets import Form, BaseFormSet, formset_factory, \
ValidationError
class QuestionForm(Form):
"""Form for a single question on a quiz"""
def __init__(self, *args, **kwargs):
# CODE TRICK #1
# pass in a question from the formset
# use the question to build the form
# pop removes from dict, so we don't pass to the parent
self.question = kwargs.pop('question')
super(QuestionForm, self).__init__(*args, **kwargs)
# CODE TRICK #2
# add a non-declared field to fields
# use an order_by clause if you care about order
self.answers = self.question.answer_set.all(
).order_by('id')
self.fields['answers'] = forms.ModelChoiceField(
queryset=self.answers())
class BaseQuizFormSet(BaseFormSet):
def __init__(self, *args, **kwargs):
# CODE TRICK #3 - same as #1:
# pass in a valid quiz object from the view
# pop removes arg, so we don't pass to the parent
self.quiz = kwargs.pop('quiz')
# CODE TRICK #4
# set length of extras based on query
# each question will fill one 'extra' slot
# use an order_by clause if you care about order
self.questions = self.quiz.question_set.all().order_by('id')
self.extra = len(self.questions)
if not self.extra:
raise Http404('Badly configured quiz has no questions.')
# call the parent constructor to finish __init__
super(BaseQuizFormSet, self).__init__(*args, **kwargs)
def _construct_form(self, index, **kwargs):
# CODE TRICK #5
# know that _construct_form is where forms get added
# we can take advantage of this fact to add our forms
# add custom kwargs, using the index to retrieve a question
# kwargs will be passed to our form class
kwargs['question'] = self.questions[index]
return super(BaseQuizFormSet, self)._construct_form(index, **kwargs)
QuizFormSet = formset_factory(
QuestionForm, formset=BaseQuizDynamicFormSet)
views.py
from django.http import Http404
def quiz_form(request, quiz_id):
try:
quiz = Quiz.objects.get(pk=quiz_id)
except Quiz.DoesNotExist:
return Http404('Invalid quiz id.')
if request.method == 'POST':
formset = QuizFormSet(quiz=quiz, data=request.POST)
answers = []
if formset.is_valid():
for form in formset.forms:
answers.append(str(int(form.is_correct())))
return HttpResponseRedirect('%s?a=%s'
% (reverse('result-display',args=[quiz_id]), ''.join(answers)))
else:
formset = QuizFormSet(quiz=quiz)
return render_to_response('quiz.html', locals())
template
{% for form in formset.forms %}
<fieldset>{{ form }}</fieldset>
{% endfor %}
I used the trick below to create a dynamic formset. Call the create_dynamic_formset() function from your view.
def create_dynamic_formset(name_filter):
"""
-Need to create the classess dynamically since there is no other way to filter
"""
class FormWithFilteredField(forms.ModelForm):
type = forms.ModelChoiceField(queryset=SomeType.objects.filter(name__icontains=name_filter))
class Meta:
model=SomeModelClass
return modelformset_factory(SomeModelClass, form=FormWithFilteredField)
Here is what I used for a similar case (a variable set of fieldsets, each one containing a variable set of fields).
I used the type() function to build my Form Class, and BetterBaseForm class from django-form-utils.
def makeFurnitureForm():
"""makeFurnitureForm() function will generate a form with
QuantityFurnitureFields."""
furnitures = Furniture.objects.all()
fieldsets = {}
fields = {}
for obj in furnitures:
# I used a custom Form Field, but you can use whatever you want.
field = QuantityFurnitureField(name = obj.name)
fields[obj.name] = field
if not obj.room in fieldsets.keys():
fieldsets[obj.room] = [field,]
else:
fieldsets[obj.room].append(field)
# Here I use a double list comprehension to define my fieldsets
# and the fields within.
# First item of each tuple is the fieldset name.
# Second item of each tuple is a dictionnary containing :
# -The names of the fields. (I used a list comprehension for this)
# -The legend of the fieldset.
# You also can add other meta attributes, like "description" or "classes",
# see the documentation for further informations.
# I added an example of output to show what the dic variable
# I create may look like.
dic = [(name, {"fields": [field.name for field in fieldsets[name]], "legend" : name})
for name in fieldsets.keys()]
print(dic)
# Here I return a class object that is my form class.
# It inherits from both forms.BaseForm and forms_utils.forms.BetterBaseForm.
return (type("FurnitureForm",
(forms.BaseForm, form_utils.forms.BetterBaseForm,),
{"_fieldsets" : dic, "base_fields" : fields,
"_fieldset_collection" : None, '_row_attrs' : {}}))
Here is an example of how dic may look like :
[('fieldset name 1',
{'legend': 'fieldset legend 2',
'fields' ['field name 1-1']}),
('fieldset name 2',
{'legend': 'fieldset legend 2',
'fields' : ['field 1-1', 'field 1-2']})]
I used BetterBaseForm rather than BetterForm for the same reason this article suggests to use BaseForm rather than Form.
This article is interesting even if it's old, and explains how to do dynamic forms (with variable set of fields). It also gives other ways to achieve dynamic forms.
It doesn't explain how to do it with fieldsets though, but it inspired me to find how to do it, and the principle remains the same.
Using it in a view is pretty simple :
return (render(request,'main/form-template.html', {"form" : (makeFurnitureForm())()}))
and in a template :
<form method="POST" name="myform" action=".">
{% csrf_token %}
<div>
{% for fieldset in form.fieldsets %}
<fieldset>
<legend>{{ fieldset.legend }}</legend>
{% for field in fieldset %}
<div>
{% include "main/furniturefieldtemplate.html" with field=field %}
</div>
{% endfor %}
</fieldset>
{% endfor %}
</div>
<input type="submit" value="Submit"/>
</form>
In a Django form, how do I make a field read-only (or disabled)?
When the form is being used to create a new entry, all fields should be enabled - but when the record is in update mode some fields need to be read-only.
For example, when creating a new Item model, all fields must be editable, but while updating the record, is there a way to disable the sku field so that it is visible, but cannot be edited?
class Item(models.Model):
sku = models.CharField(max_length=50)
description = models.CharField(max_length=200)
added_by = models.ForeignKey(User)
class ItemForm(ModelForm):
class Meta:
model = Item
exclude = ('added_by')
def new_item_view(request):
if request.method == 'POST':
form = ItemForm(request.POST)
# Validate and save
else:
form = ItemForm()
# Render the view
Can class ItemForm be reused? What changes would be required in the ItemForm or Item model class? Would I need to write another class, "ItemUpdateForm", for updating the item?
def update_item_view(request):
if request.method == 'POST':
form = ItemUpdateForm(request.POST)
# Validate and save
else:
form = ItemUpdateForm()
As pointed out in this answer, Django 1.9 added the Field.disabled attribute:
The disabled boolean argument, when set to True, disables a form field using the disabled HTML attribute so that it won’t be editable by users. Even if a user tampers with the field’s value submitted to the server, it will be ignored in favor of the value from the form’s initial data.
With Django 1.8 and earlier, to disable entry on the widget and prevent malicious POST hacks you must scrub the input in addition to setting the readonly attribute on the form field:
class ItemForm(ModelForm):
def __init__(self, *args, **kwargs):
super(ItemForm, self).__init__(*args, **kwargs)
instance = getattr(self, 'instance', None)
if instance and instance.pk:
self.fields['sku'].widget.attrs['readonly'] = True
def clean_sku(self):
instance = getattr(self, 'instance', None)
if instance and instance.pk:
return instance.sku
else:
return self.cleaned_data['sku']
Or, replace if instance and instance.pk with another condition indicating you're editing. You could also set the attribute disabled on the input field, instead of readonly.
The clean_sku function will ensure that the readonly value won't be overridden by a POST.
Otherwise, there is no built-in Django form field which will render a value while rejecting bound input data. If this is what you desire, you should instead create a separate ModelForm that excludes the uneditable field(s), and just print them inside your template.
Django 1.9 added the Field.disabled attribute: https://docs.djangoproject.com/en/stable/ref/forms/fields/#disabled
The disabled boolean argument, when set to True, disables a form field using the disabled HTML attribute so that it won’t be editable by users. Even if a user tampers with the field’s value submitted to the server, it will be ignored in favor of the value from the form’s initial data.
Setting readonly on a widget only makes the input in the browser read-only. Adding a clean_sku which returns instance.sku ensures the field value will not change on form level.
def clean_sku(self):
if self.instance:
return self.instance.sku
else:
return self.fields['sku']
This way you can use model's (unmodified save) and avoid getting the field required error.
awalker's answer helped me a lot!
I've changed his example to work with Django 1.3, using get_readonly_fields.
Usually you should declare something like this in app/admin.py:
class ItemAdmin(admin.ModelAdmin):
...
readonly_fields = ('url',)
I've adapted in this way:
# In the admin.py file
class ItemAdmin(admin.ModelAdmin):
...
def get_readonly_fields(self, request, obj=None):
if obj:
return ['url']
else:
return []
And it works fine. Now if you add an Item, the url field is read-write, but on change it becomes read-only.
To make this work for a ForeignKey field, a few changes need to be made. Firstly, the SELECT HTML tag does not have the readonly attribute. We need to use disabled="disabled" instead. However, then the browser doesn't send any form data back for that field. So we need to set that field to not be required so that the field validates correctly. We then need to reset the value back to what it used to be so it's not set to blank.
So for foreign keys you will need to do something like:
class ItemForm(ModelForm):
def __init__(self, *args, **kwargs):
super(ItemForm, self).__init__(*args, **kwargs)
instance = getattr(self, 'instance', None)
if instance and instance.id:
self.fields['sku'].required = False
self.fields['sku'].widget.attrs['disabled'] = 'disabled'
def clean_sku(self):
# As shown in the above answer.
instance = getattr(self, 'instance', None)
if instance:
return instance.sku
else:
return self.cleaned_data.get('sku', None)
This way the browser won't let the user change the field, and will always POST as it it was left blank. We then override the clean method to set the field's value to be what was originally in the instance.
For Django 1.2+, you can override the field like so:
sku = forms.CharField(widget = forms.TextInput(attrs={'readonly':'readonly'}))
I made a MixIn class which you may inherit to be able to add a read_only iterable field which will disable and secure fields on the non-first edit:
(Based on Daniel's and Muhuk's answers)
from django import forms
from django.db.models.manager import Manager
# I used this instead of lambda expression after scope problems
def _get_cleaner(form, field):
def clean_field():
value = getattr(form.instance, field, None)
if issubclass(type(value), Manager):
value = value.all()
return value
return clean_field
class ROFormMixin(forms.BaseForm):
def __init__(self, *args, **kwargs):
super(ROFormMixin, self).__init__(*args, **kwargs)
if hasattr(self, "read_only"):
if self.instance and self.instance.pk:
for field in self.read_only:
self.fields[field].widget.attrs['readonly'] = "readonly"
setattr(self, "clean_" + field, _get_cleaner(self, field))
# Basic usage
class TestForm(AModelForm, ROFormMixin):
read_only = ('sku', 'an_other_field')
I ran across a similar problem.
It looks like I was able to solve it by defining a get_readonly_fields method in my ModelAdmin class.
Something like this:
# In the admin.py file
class ItemAdmin(admin.ModelAdmin):
def get_readonly_display(self, request, obj=None):
if obj:
return ['sku']
else:
return []
The nice thing is that obj will be None when you are adding a new Item, or it will be the object being edited when you are changing an existing Item.
get_readonly_display is documented here.
I've just created the simplest possible widget for a readonly field - I don't really see why forms don't have this already:
class ReadOnlyWidget(widgets.Widget):
"""Some of these values are read only - just a bit of text..."""
def render(self, _, value, attrs=None):
return value
In the form:
my_read_only = CharField(widget=ReadOnlyWidget())
Very simple - and gets me just output. Handy in a formset with a bunch of read only values.
Of course - you could also be a bit more clever and give it a div with the attrs so you can append classes to it.
For django 1.9+
You can use Fields disabled argument to make field disable.
e.g. In following code snippet from forms.py file , I have made employee_code field disabled
class EmployeeForm(forms.ModelForm):
employee_code = forms.CharField(disabled=True)
class Meta:
model = Employee
fields = ('employee_code', 'designation', 'salary')
Reference
https://docs.djangoproject.com/en/dev/ref/forms/fields/#disabled
How I do it with Django 1.11 :
class ItemForm(ModelForm):
disabled_fields = ('added_by',)
class Meta:
model = Item
fields = '__all__'
def __init__(self, *args, **kwargs):
super(ItemForm, self).__init__(*args, **kwargs)
for field in self.disabled_fields:
self.fields[field].disabled = True
One simple option is to just type form.instance.fieldName in the template instead of form.fieldName.
You can elegantly add readonly in the widget:
class SurveyModaForm(forms.ModelForm):
class Meta:
model = Survey
fields = ['question_no']
widgets = {
'question_no':forms.NumberInput(attrs={'class':'form-control','readonly':True}),
}
Yet again, I am going to offer one more solution :) I was using Humphrey's code, so this is based off of that.
However, I ran into issues with the field being a ModelChoiceField. Everything would work on the first request. However, if the formset tried to add a new item and failed validation, something was going wrong with the "existing" forms where the SELECTED option was being reset to the default ---------.
Anyway, I couldn't figure out how to fix that. So instead, (and I think this is actually cleaner in the form), I made the fields HiddenInputField(). This just means you have to do a little more work in the template.
So the fix for me was to simplify the Form:
class ItemForm(ModelForm):
def __init__(self, *args, **kwargs):
super(ItemForm, self).__init__(*args, **kwargs)
instance = getattr(self, 'instance', None)
if instance and instance.id:
self.fields['sku'].widget=HiddenInput()
And then in the template, you'll need to do some manual looping of the formset.
So, in this case you would do something like this in the template:
<div>
{{ form.instance.sku }} <!-- This prints the value -->
{{ form }} <!-- Prints form normally, and makes the hidden input -->
</div>
This worked a little better for me and with less form manipulation.
I was going into the same problem so I created a Mixin that seems to work for my use cases.
class ReadOnlyFieldsMixin(object):
readonly_fields =()
def __init__(self, *args, **kwargs):
super(ReadOnlyFieldsMixin, self).__init__(*args, **kwargs)
for field in (field for name, field in self.fields.iteritems() if name in self.readonly_fields):
field.widget.attrs['disabled'] = 'true'
field.required = False
def clean(self):
cleaned_data = super(ReadOnlyFieldsMixin,self).clean()
for field in self.readonly_fields:
cleaned_data[field] = getattr(self.instance, field)
return cleaned_data
Usage, just define which ones must be read only:
class MyFormWithReadOnlyFields(ReadOnlyFieldsMixin, MyForm):
readonly_fields = ('field1', 'field2', 'fieldx')
As a useful addition to Humphrey's post, I had some issues with django-reversion, because it still registered disabled fields as 'changed'. The following code fixes the problem.
class ItemForm(ModelForm):
def __init__(self, *args, **kwargs):
super(ItemForm, self).__init__(*args, **kwargs)
instance = getattr(self, 'instance', None)
if instance and instance.id:
self.fields['sku'].required = False
self.fields['sku'].widget.attrs['disabled'] = 'disabled'
def clean_sku(self):
# As shown in the above answer.
instance = getattr(self, 'instance', None)
if instance:
try:
self.changed_data.remove('sku')
except ValueError, e:
pass
return instance.sku
else:
return self.cleaned_data.get('sku', None)
As I can't yet comment (muhuk's solution), I'll response as a separate answer. This is a complete code example, that worked for me:
def clean_sku(self):
if self.instance and self.instance.pk:
return self.instance.sku
else:
return self.cleaned_data['sku']
Based on Yamikep's answer, I found a better and very simple solution which also handles ModelMultipleChoiceField fields.
Removing field from form.cleaned_data prevents fields from being saved:
class ReadOnlyFieldsMixin(object):
readonly_fields = ()
def __init__(self, *args, **kwargs):
super(ReadOnlyFieldsMixin, self).__init__(*args, **kwargs)
for field in (field for name, field in self.fields.iteritems() if
name in self.readonly_fields):
field.widget.attrs['disabled'] = 'true'
field.required = False
def clean(self):
for f in self.readonly_fields:
self.cleaned_data.pop(f, None)
return super(ReadOnlyFieldsMixin, self).clean()
Usage:
class MyFormWithReadOnlyFields(ReadOnlyFieldsMixin, MyForm):
readonly_fields = ('field1', 'field2', 'fieldx')
if your need multiple read-only fields.you can use any of methods given below
method 1
class ItemForm(ModelForm):
readonly = ('sku',)
def __init__(self, *arg, **kwrg):
super(ItemForm, self).__init__(*arg, **kwrg)
for x in self.readonly:
self.fields[x].widget.attrs['disabled'] = 'disabled'
def clean(self):
data = super(ItemForm, self).clean()
for x in self.readonly:
data[x] = getattr(self.instance, x)
return data
method 2
inheritance method
class AdvancedModelForm(ModelForm):
def __init__(self, *arg, **kwrg):
super(AdvancedModelForm, self).__init__(*arg, **kwrg)
if hasattr(self, 'readonly'):
for x in self.readonly:
self.fields[x].widget.attrs['disabled'] = 'disabled'
def clean(self):
data = super(AdvancedModelForm, self).clean()
if hasattr(self, 'readonly'):
for x in self.readonly:
data[x] = getattr(self.instance, x)
return data
class ItemForm(AdvancedModelForm):
readonly = ('sku',)
Two more (similar) approaches with one generalized example:
1) first approach - removing field in save() method, e.g. (not tested ;) ):
def save(self, *args, **kwargs):
for fname in self.readonly_fields:
if fname in self.cleaned_data:
del self.cleaned_data[fname]
return super(<form-name>, self).save(*args,**kwargs)
2) second approach - reset field to initial value in clean method:
def clean_<fieldname>(self):
return self.initial[<fieldname>] # or getattr(self.instance, fieldname)
Based on second approach I generalized it like this:
from functools import partial
class <Form-name>(...):
def __init__(self, ...):
...
super(<Form-name>, self).__init__(*args, **kwargs)
...
for i, (fname, field) in enumerate(self.fields.iteritems()):
if fname in self.readonly_fields:
field.widget.attrs['readonly'] = "readonly"
field.required = False
# set clean method to reset value back
clean_method_name = "clean_%s" % fname
assert clean_method_name not in dir(self)
setattr(self, clean_method_name, partial(self._clean_for_readonly_field, fname=fname))
def _clean_for_readonly_field(self, fname):
""" will reset value to initial - nothing will be changed
needs to be added dynamically - partial, see init_fields
"""
return self.initial[fname] # or getattr(self.instance, fieldname)
For the Admin version, I think this is a more compact way if you have more than one field:
def get_readonly_fields(self, request, obj=None):
skips = ('sku', 'other_field')
fields = super(ItemAdmin, self).get_readonly_fields(request, obj)
if not obj:
return [field for field in fields if not field in skips]
return fields
Here is a slightly more involved version, based on christophe31's answer. It does not rely on the "readonly" attribute. This makes its problems, like select boxes still being changeable and datapickers still popping up, go away.
Instead, it wraps the form fields widget in a readonly widget, thus making the form still validate. The content of the original widget is displayed inside <span class="hidden"></span> tags. If the widget has a render_readonly() method it uses that as the visible text, otherwise it parses the HTML of the original widget and tries to guess the best representation.
import django.forms.widgets as f
import xml.etree.ElementTree as etree
from django.utils.safestring import mark_safe
def make_readonly(form):
"""
Makes all fields on the form readonly and prevents it from POST hacks.
"""
def _get_cleaner(_form, field):
def clean_field():
return getattr(_form.instance, field, None)
return clean_field
for field_name in form.fields.keys():
form.fields[field_name].widget = ReadOnlyWidget(
initial_widget=form.fields[field_name].widget)
setattr(form, "clean_" + field_name,
_get_cleaner(form, field_name))
form.is_readonly = True
class ReadOnlyWidget(f.Select):
"""
Renders the content of the initial widget in a hidden <span>. If the
initial widget has a ``render_readonly()`` method it uses that as display
text, otherwise it tries to guess by parsing the html of the initial widget.
"""
def __init__(self, initial_widget, *args, **kwargs):
self.initial_widget = initial_widget
super(ReadOnlyWidget, self).__init__(*args, **kwargs)
def render(self, *args, **kwargs):
def guess_readonly_text(original_content):
root = etree.fromstring("<span>%s</span>" % original_content)
for element in root:
if element.tag == 'input':
return element.get('value')
if element.tag == 'select':
for option in element:
if option.get('selected'):
return option.text
if element.tag == 'textarea':
return element.text
return "N/A"
original_content = self.initial_widget.render(*args, **kwargs)
try:
readonly_text = self.initial_widget.render_readonly(*args, **kwargs)
except AttributeError:
readonly_text = guess_readonly_text(original_content)
return mark_safe("""<span class="hidden">%s</span>%s""" % (
original_content, readonly_text))
# Usage example 1.
self.fields['my_field'].widget = ReadOnlyWidget(self.fields['my_field'].widget)
# Usage example 2.
form = MyForm()
make_readonly(form)
Today I encountered the exact same problem for a similar use case. However, I had to deal with a class-based views. Class-based views allow inheriting attributes and methods thus making it easier to reuse code in a neat manner.
I will answer your question by discussing the code needed for creating a profile page for users. On this page, they can update their personal information. However, I wanted to show an email field without allowing the user to change the information.
Yes, I could have just left out the email field but my OCD would not allow it.
In the example below I used a form class in combination with the disabled = True method. This code is tested on Django==2.2.7.
# form class in forms.py
# Alter import User if you have created your own User class with Django default as abstract class.
from .models import User
# from django.contrib.auth.models import User
# Same goes for these forms.
from django.contrib.auth.forms import UserCreationForm, UserChangeForm
class ProfileChangeForm(UserChangeForm):
class Meta(UserCreationForm)
model = User
fields = ['first_name', 'last_name', 'email',]
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
self.fields['email'].disabled = True
As one can see, the needed user fields are specified. These are the fields that must be shown on the profile page. If other fields need to be added one has to specify them in the User class and add the attribute name to the fields list of the Meta class of this form.
After getting the required metadata the __init__ method is called initializing the form. However, within this method, the email field parameter 'disabled' is set to True. By doing so the behavior of the field in the front-end is altered resulting in a read-only field that one cannot edit even if one changes the HTML code. Reference Field.disabled
For completion, in the example below one can see the class-based views needed to use the form.
# view class in views.py
from django.contrib import messages
from django.contrib.messages.views import SuccessMessageMixin
from django.contrib.auth.mixins import LoginRequiredMixin
from django.views.generic import TemplateView, UpdateView
from django.utils.translation import gettext_lazy as _
class ProfileView(LoginRequiredMixin, TemplateView):
template_name = 'app_name/profile.html'
model = User
def get_context_data(self, **kwargs):
context = super().get_context_data(**kwargs)
context.update({'user': self.request.user, })
return context
class UserUpdateView(LoginRequiredMixin, SuccesMessageMixin, UpdateView):
template_name = 'app_name/update_profile.html'
model = User
form_class = ProfileChangeForm
success_message = _("Successfully updated your personal information")
def get_success_url(self):
# Please note, one has to specify a get_absolute_url() in the User class
# In my case I return: reverse("app_name:profile")
return self.request.user.get_absolute_url()
def get_object(self, **kwargs):
return self.request.user
def form_valid(self, form):
messages.add_message(self.request, messages.INFO, _("Successfully updated your profile"))
return super().form_valid(form)
The ProfileView class only shows an HTML page with some information about the user. Furthermore, it holds a button that if pressed leads to an HTML page configured by the UserUpdateView, namely 'app_name/update_profile.html'. As one can see, the UserUpdateView holds two extra attributes, namely 'form_class' and 'success_message'.
The view knows that every field on the page must be filled with data from the User model. However, by introducing the 'form_class' attribute the view does not get the default layout of the User fields. Instead, it is redirected to retrieve the fields through the form class. This has a huge advantage in the sense of flexibility.
By using form classes it is possible to show different fields with different restrictions for different users. If one sets the restrictions within the model itself every user would get the same treatment.
The template itself is not that spectacular but can be seen below.
# HTML template in 'templates/app_name/update_profile.html'
{% extends "base.html" %}
{% load static %}
{% load crispy_form_tags %}
{% block content %}
<h1>
Update your personal information
<h1/>
<div>
<form class="form-horizontal" method="post" action="{% url 'app_name:update' %}">
{% csrf_token %}
{{ form|crispy }}
<div class="btn-group">
<button type="submit" class="btn btn-primary">
Update
</button>
</div>
</div>
{% endblock %}
As can be seen, the form tag holds an action tag that holds the view URL routing.
After pressing the Update button the UserUpdateView gets activated and it validates if all conditions are met. If so, the form_valid method is triggered and adds a success message. After successfully updating the data the user is returned to the specified URL in the get_success_url method.
Below one can find the code allowing the URL routing for the views.
# URL routing for views in urls.py
from django.urls import path
from . import views
app_name = 'app_name'
urlpatterns = [
path('profile/', view=views.ProfileView.as_view(), name='profile'),
path('update/', view=views.UserUpdateView.as_view(), name='update'),
]
There you have it. A fully worked out implementation of class-based views using form so one can alter an email field to be read-only and disabled.
My apologies for the extremely detailed example. There might be more efficient ways to design the class-based views, but this should work. Of course, I might have been wrong about some things said. I'm still learning as well. If anyone has any comments or improvements let me know!
You can do it just like this:
Check if the request is update or save a new object.
If request is update then disable field sku.
If request is to add a new object then you must render the form with out disabling the field sku.
Here is an example of how to do like this.
class Item(models.Model):
sku = models.CharField(max_length=50)
description = models.CharField(max_length=200)
added_by = models.ForeignKey(User)
class ItemForm(ModelForm):
def disable_sku_field(self):
elf.fields['sku'].widget.attrs['readonly'] = True
class Meta:
model = Item
exclude = ('added_by')
def new_item_view(request):
if request.method == 'POST':
form = ItemForm(request.POST)
# Just create an object or instance of the form.
# Validate and save
else:
form = ItemForm()
# Render the view
def update_item_view(request):
if request.method == 'POST':
form = ItemForm(request.POST)
# Just create an object or instance of the form.
# Validate and save
else:
form = ItemForm()
form.disable_sku_field() # call the method that will disable field.
# Render the view with the form that will have the `sku` field disabled on it.
Is this the simplest way?
Right in a view code something like this:
def resume_edit(request, r_id):
.....
r = Resume.get.object(pk=r_id)
resume = ResumeModelForm(instance=r)
.....
resume.fields['email'].widget.attrs['readonly'] = True
.....
return render(request, 'resumes/resume.html', context)
It works fine!
If you are working with Django ver < 1.9 (the 1.9 has added Field.disabled attribute) you could try to add following decorator to your form __init__ method:
def bound_data_readonly(_, initial):
return initial
def to_python_readonly(field):
native_to_python = field.to_python
def to_python_filed(_):
return native_to_python(field.initial)
return to_python_filed
def disable_read_only_fields(init_method):
def init_wrapper(*args, **kwargs):
self = args[0]
init_method(*args, **kwargs)
for field in self.fields.values():
if field.widget.attrs.get('readonly', None):
field.widget.attrs['disabled'] = True
setattr(field, 'bound_data', bound_data_readonly)
setattr(field, 'to_python', to_python_readonly(field))
return init_wrapper
class YourForm(forms.ModelForm):
#disable_read_only_fields
def __init__(self, *args, **kwargs):
...
The main idea is that if field is readonly you don't need any other value except initial.
P.S: Don't forget to set yuor_form_field.widget.attrs['readonly'] = True
Start from disable fields mixin:
class ModelAllDisabledFormMixin(forms.ModelForm):
def __init__(self, *args, **kwargs):
'''
This mixin to ModelForm disables all fields. Useful to have detail view based on model
'''
super().__init__(*args, **kwargs)
form_fields = self.fields
for key in form_fields.keys():
form_fields[key].disabled = True
then:
class MyModelAllDisabledForm(ModelAllDisabledFormMixin, forms.ModelForm):
class Meta:
model = MyModel
fields = '__all__'
prepare view:
class MyModelDetailView(LoginRequiredMixin, UpdateView):
model = MyModel
template_name = 'my_model_detail.html'
form_class = MyModelAllDisabledForm
place this in my_model_detail.html template:
<div class="form">
<form method="POST" enctype="multipart/form-data">
{% csrf_token %}
{{ form | crispy }}
</form>
</div>
You will obtain same form as in update view but with all fields disabled.
Based on the answer from #paeduardo (which is overkill), you can disable a field in the form class initializer:
class RecordForm(ModelForm):
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
var = self.fields['the_field']
var.disabled = True
If you are using Django admin, here is the simplest solution.
class ReadonlyFieldsMixin(object):
def get_readonly_fields(self, request, obj=None):
if obj:
return super(ReadonlyFieldsMixin, self).get_readonly_fields(request, obj)
else:
return tuple()
class MyAdmin(ReadonlyFieldsMixin, ModelAdmin):
readonly_fields = ('sku',)
I think your best option would just be to include the readonly attribute in your template rendered in a <span> or <p> rather than include it in the form if it's readonly.
Forms are for collecting data, not displaying it. That being said, the options to display in a readonly widget and scrub POST data are fine solutions.