I want to add the request context to my serializer in the Django REST framework. In particular to a nested serializer, i (successfully) tried to do that with a SerializerMethodField ( as my solution per: context in nested serializers django rest framework ). This is the setup i use:
class VehicleTypeSerializer(RsModelSerializer):
class Meta:
model = VehicleType
class VehicleSerializer(RsModelSerializer):
vehicletype = SerializerMethodField()
class Meta:
model = Vehicle
fields = ('vehiclename', 'vehicledescription', 'vehicletype')
def get_vehicletype(self, obj):
return self.get_serializermethodfield_data(obj, VehicleType, VehicleTypeSerializer, 'vehicle')
def get_serializermethodfield_data(self, obj, model_class, serializer_class, filter_field):
filter = {filter_field: obj}
objs = model_class.objects.all().filter(**filter)
# We need the request-context for checking field permissions in the serializer
s = serializer_class(objs, many=True, context={'request': self.context.get('request')})
return s.data
Problem : I need a SerializerMethodField to pass the request-context to the nested-serializer (VehicleTypeSerializer)
But now i am stuck dealing with POST's since the SerializerMethodField is read-only. I can't POST an object to /api/v1/vehicle with:
{
"vehiclename": "test",
"vehicledescription": "test"
"vehicletype": "1" <---- get's ignored since SerializerMethodField is read-only
}
Question : Can someone point me in the right direction to add the request-context (especially the user information) to a nested serializer which i can write to?
I need the request context (request.user) in the VehicleSerializer as well as in the VechileTypeSerializer, because in the RsModelSerializer that i have defined, i check on a per-field-basis if the user that is doing the request has permission to read or update a field.
In the RsModelSerializer:
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
# Make sure that there is a user mapped in the context (we need a user
# for checking permissions on a field). If there is no user, we set
# the user to None.
if not self.context:
self._context = getattr(self.Meta, 'context', {})
try:
self.user = self.context['request'].user
except (KeyError, AttributeError):
print('No request')
self.user = None
def get_fields(self):
"""
Override get_fields to ensure only fields that are allowed
by model-field-permissions are returned to the serializer
:return: Dict with allowed fields
"""
ret = OrderedDict()
fields = super().get_fields()
# If no user is associated with the serializer, return no fields
if self.user == None:
return None
# A superuser bypasses the permissions-check and gets all
# available fields
if self.user.is_superuser:
print_without_test("user is superuser, bypassing permissions")
return fields
# Walk through all available fields and check if a user has permission for
# it. If he does, add them to a return-array. This way all fields that
# are not allowed to 'read' will be dropped. Note: this is only used
# for read access. Write access is handled in the views (modelviewsets).
for f in fields:
if has_permission(user=self.user, app_label=self.Meta.model._meta.app_label,
table=self.Meta.model.__name__.lower(),
field=f,
permission='read'):
ret[f] = fields[f]
return ret
Method-1: Overriding the __init__() method of parent serializer
You can add the context to nested/child serializer in the __init__() method of parent serializer.
class RsModelSerializer(serializers.ModelSerializer):
def __init__(self, *args, **kwargs):
super(RsModelSerializer, self).__init__(*args, **kwargs)
request_obj = self.context.get('request') # get the request from parent serializer's context
# assign request object to nested serializer context
self.fields['nested_serializer_field'].context['request'] = request_obj
We cannot pass the context to nested serializer at the time of their __init__() because they get initialized at the time of declaration in the parent serializer.
class SomeParentSerializer(serializers.Serializer):
some_child = SomeChildSerializer() # gets initialized here
Method-2: Passing context when child serializer gets binded to its parent
Another option is to add the context when a child/nested serializer gets binded to the parent.
class SomeChildSerializer(Serializer):
def bind(self, field_name, parent):
super(SomeChildSerializer, self).bind(field_name, parent) # child gets binded to parent
request_obj = parent.context.get('request') # get the request from parent serializer context
self.context['request'] = request_obj
Quoting the DRF author's suggested option in the related ticket:
This should be considered private API, and the parent
__init__ style listed above should be preferred.
So, the better option is to override the __init__() method of ParentSerializer and pass the context to child/nested serializer.
(Source: check this related ticket on Github.)
If you need to pass a context to Serializer class. You can use Serializer's context
And you will be able to use it in a SerializerMethodField
class MySerializer(serializer.Serializer)
field = serializer.SerializerMethodField()
def get_field(self, obj):
return self.context.get('my_key')
You call it from view:
...
s = MySerializer(data=data, context={'my_key': 'my_value'})
...
EDIT:
If you need use this context in another Serializer class, pass to the first serializer in the pass to the nexted serializer:
# views.py
...
s = MySerializer(data=data, context={'my_key': 'my_value'})
...
# serializers.py
class MySerializer(serializer.Serializer):
field = serializer.SerializerMethodField()
def get_field(self, obj):
return MySecondSerializer(..., context=self.context)
I want to have additional fields regarding value of one field. Therefor I build a custom admin form to add some new fields.
Related to the blogpost of jacobian 1 this is what I came up with:
class ProductAdminForm(forms.ModelForm):
class Meta:
model = Product
def __init__(self, *args, **kwargs):
super(ProductAdminForm, self).__init__(*args, **kwargs)
self.fields['foo'] = forms.IntegerField(label="foo")
class ProductAdmin(admin.ModelAdmin):
form = ProductAdminForm
admin.site.register(Product, ProductAdmin)
But the additional field 'foo' does not show up in the admin. If I add the field like this, all works fine but is not as dynamic as required, to add the fields regarding the value of another field of the model
class ProductAdminForm(forms.ModelForm):
foo = forms.IntegerField(label="foo")
class Meta:
model = Product
class ProductAdmin(admin.ModelAdmin):
form = ProductAdminForm
admin.site.register(Product, ProductAdmin)
So is there any initialize method that i have to trigger again to make the new field working? Or is there any other attempt?
Here is a solution to the problem. Thanks to koniiiik i tried to solve this by extending the *get_fieldsets* method
class ProductAdmin(admin.ModelAdmin):
def get_fieldsets(self, request, obj=None):
fieldsets = super(ProductAdmin, self).get_fieldsets(request, obj)
fieldsets[0][1]['fields'] += ['foo']
return fieldsets
If you use multiple fieldsets be sure to add the to the right fieldset by using the appropriate index.
The accepted answer above worked in older versions of django, and that's how I was doing it. This has now broken in later django versions (I am on 1.68 at the moment, but even that is old now).
The reason it is now broken is because any fields within fieldsets you return from ModelAdmin.get_fieldsets() are ultimately passed as the fields=parameter to modelform_factory(), which will give you an error because the fields on your list do not exist (and will not exist until your form is instantiated and its __init__ is called).
In order to fix this, we must override ModelAdmin.get_form() and supply a list of fields that does not include any extra fields that will be added later. The default behavior of get_form is to call get_fieldsets() for this information, and we must prevent that from happening:
# CHOOSE ONE
# newer versions of django use this
from django.contrib.admin.utils import flatten_fieldsets
# if above does not work, use this
from django.contrib.admin.util import flatten_fieldsets
class MyModelForm(ModelForm):
def __init__(self, *args, **kwargs):
super(MyModelForm, self).__init__(*args, **kwargs)
# add your dynamic fields here..
for fieldname in ('foo', 'bar', 'baz',):
self.fields[fieldname] = form.CharField()
class MyAdmin(ModelAdmin):
form = MyModelForm
fieldsets = [
# here you put the list of fieldsets you want displayed.. only
# including the ones that are not dynamic
]
def get_form(self, request, obj=None, **kwargs):
# By passing 'fields', we prevent ModelAdmin.get_form from
# looking up the fields itself by calling self.get_fieldsets()
# If you do not do this you will get an error from
# modelform_factory complaining about non-existent fields.
# use this line only for django before 1.9 (but after 1.5??)
kwargs['fields'] = flatten_fieldsets(self.declared_fieldsets)
# use this line only for django 1.9 and later
kwargs['fields'] = flatten_fieldsets(self.fieldsets)
return super(MyAdmin, self).get_form(request, obj, **kwargs)
def get_fieldsets(self, request, obj=None):
fieldsets = super(MyAdmin, self).get_fieldsets(request, obj)
newfieldsets = list(fieldsets)
fields = ['foo', 'bar', 'baz']
newfieldsets.append(['Dynamic Fields', { 'fields': fields }])
return newfieldsets
This works for adding dynamic fields in Django 1.9.3, using just a ModelAdmin class (no ModelForm) and by overriding get_fields. I don't know yet how robust it is:
class MyModelAdmin(admin.ModelAdmin):
fields = [('title','status', ), 'description', 'contact_person',]
exclude = ['material']
def get_fields(self, request, obj=None):
gf = super(MyModelAdmin, self).get_fields(request, obj)
new_dynamic_fields = [
('test1', forms.CharField()),
('test2', forms.ModelMultipleChoiceField(MyModel.objects.all(), widget=forms.CheckboxSelectMultiple)),
]
#without updating get_fields, the admin form will display w/o any new fields
#without updating base_fields or declared_fields, django will throw an error: django.core.exceptions.FieldError: Unknown field(s) (test) specified for MyModel. Check fields/fieldsets/exclude attributes of class MyModelAdmin.
for f in new_dynamic_fields:
#`gf.append(f[0])` results in multiple instances of the new fields
gf = gf + [f[0]]
#updating base_fields seems to have the same effect
self.form.declared_fields.update({f[0]:f[1]})
return gf
Maybe I am a bit late... However, I am using Django 3.0 and also wanted to dynamically ad some custom fields to the form, depending on the request.
I end up with a solution similar to the one described by #tehfink combined with #little_birdie.
However, just updating self.form.declared_fields as suggested didn't help. The result of this procedure is, that the list of custom fields defined in self.form.declared_fields always grows from request to request.
I solved this by initialising this dictionary first:
class ModelAdminGetCustomFieldsMixin(object):
def get_fields(self, request, obj=None):
fields = super().get_fields(request, obj=None)
self.form.declared_fields = {}
if obj:
for custom_attribute in custom_attribute_list:
self.form.declared_fields.update({custom_attribute.name: custom_attribute.field})
return fields
where custom_attribute.field is a form field instance.
Additionally, it was required to define a ModelForm, wherein during initialisation the custom fields have been added dynamically as well:
class SomeModelForm(forms.ModelForm):
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
for custom_attribute in custom_attribute_list:
self.fields[custom_attribute.name] = custom_attribute.field
and use this ModelForm in the ModelAdmin.
Afterwards, the newly defined attributes can be used in, e.g., a fieldset.
While Jacob's post might work all right for regular ModelForms (even though it's more than a year and a half old), the admin is a somewhat different matter.
All the declarative way of defining models, forms ModelAdmins and whatnot makes heavy use of metaclasses and class introspection. Same with the admin – when you tell a ModelAdmin to use a specific form istead of creating a default one, it introspects the class. It gets the list of fields and other stuff from the class itself without instantiating it.
Your custom class, however, does not define the extra form field at class level, instead it dynamically adds one after it has been instantiated – that's too late for the ModelAdmin to recognize this change.
One way to go about your problem might be to subclass ModelAdmin and override its get_fieldsets method to actually instantiate the ModelForm class and get the list of fields from the instance instead of the class. You'll have to keep in mind, though, that this might be somewhat slower than the default implementation.
You can create dynamic fields and fieldset using the form meta class. Sample code is given below. Add the loop logic as per you requirements.
class CustomAdminFormMetaClass(ModelFormMetaclass):
"""
Metaclass for custom admin form with dynamic field
"""
def __new__(cls, name, bases, attrs):
for field in get_dynamic_fields: #add logic to get the fields
attrs[field] = forms.CharField(max_length=30) #add logic to the form field
return super(CustomAdminFormMetaClass, cls).__new__(cls, name, bases, attrs)
class CustomAdminForm(six.with_metaclass(CustomAdminFormMetaClass, forms.ModelForm)):
"""
Custom admin form
"""
class Meta:
model = ModelName
fields = "__all__"
class CustomAdmin(admin.ModelAdmin):
"""
Custom admin
"""
fieldsets = None
form = CustomAdminForm
def get_fieldsets(self, request, obj=None):
"""
Different fieldset for the admin form
"""
self.fieldsets = self.dynamic_fieldset(). #add logic to add the dynamic fieldset with fields
return super(CustomAdmin, self).get_fieldsets(request, obj)
def dynamic_fieldset(self):
"""
get the dynamic field sets
"""
fieldsets = []
for group in get_field_set_groups: #logic to get the field set group
fields = []
for field in get_group_fields: #logic to get the group fields
fields.append(field)
fieldset_values = {"fields": tuple(fields), "classes": ['collapse']}
fieldsets.append((group, fieldset_values))
fieldsets = tuple(fieldsets)
return fieldsets
Stephan's answer is elegant, but when I used in in dj1.6 it required the field to be a tuple.
The complete solution looked like this:
class ProductForm(ModelForm):
foo = CharField(label='foo')
class ProductAdmin(admin.ModelAdmin):
form = ProductForm
def get_fieldsets(self, request, obj=None):
fieldsets = super(ProductAdmin, self).get_fieldsets(request, obj)
fieldsets[0][1]['fields'] += ('foo', )
return fieldsets
not sure why that's not working, but could a possible workaround be to define the field statically (on the form) and then override it in the __init__?
I for a long time could not solve a problem with dynamic addition of fields.
The solution "little_birdie" really works. Thank you Birdie))
The only nuance is:
"Self.declared_fieldsets" should be replaced with "self.fieldsets".
#kwargs['fields'] = flatten_fieldsets(self.declared_fieldsets)
kwargs['fields'] = flatten_fieldsets(self.fieldsets)
I used version 1.10. Perhaps something has changed.
If someone finds an even simpler and elegant solution, show here.
Thanks to all )))
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.