Develop Reference

ModelForm saving over model data with empty fields

I'm building an Edit form for a model in my database using a ModelForm in Django. Each field in the form is optional as the user may want to only edit one field.
The problem I am having is that when I call save() in the view, any empty fields are being saved over the instance's original values (e.g. if I only enter a new first_name, the last_name and ecf_code fields will save an empty string in the corresponding instance.)
The form:
class EditPlayerForm(forms.ModelForm):
class Meta:
model = Player
fields = ['first_name', 'last_name', 'ecf_code']
def __init__(self, *args, **kwargs):
super(EditPlayerForm, self).__init__(*args, **kwargs)
self.fields['first_name'].required = False
self.fields['last_name'].required = False
self.fields['ecf_code'].required = False
The view:
def view(request, player_pk = ''):
edit_player_form = forms.EditPlayerForm(auto_id="edit_%s")
if "edit_player_form" in request.POST:
if not player_pk:
messages.error(request, "No player pk given.")
else:
try:
selected_player = Player.objects.get(pk = player_pk)
except Player.DoesNotExist:
messages.error(request, "The selected player could not be found in the database.")
return redirect("players:management")
else:
edit_player_form = forms.EditPlayerForm(
request.POST,
instance = selected_player
)
if edit_player_form.is_valid():
player = edit_player_form.save()
messages.success(request, "The changes were made successfully.")
return redirect("players:management")
else:
form_errors.convert_form_errors_to_messages(edit_player_form, request)
return render(
request,
"players/playerManagement.html",
{
"edit_player_form": edit_player_form,
"players": Player.objects.all(),
}
)
I've tried overriding the save() method of the form to explicitly check which fields have values in the POST request but that didn't seem to make any difference either.
Attempt at overriding the save method:
def save(self, commit = True):
# Tried this way to get instance as well
# instance = super(EditPlayerForm, self).save(commit = False)
self.cleaned_data = dict([ (k,v) for k,v in self.cleaned_data.items() if v != "" ])
try:
self.instance.first_name = self.cleaned_data["first_name"]
except KeyError:
pass
try:
self.instance.last_name = self.cleaned_data["last_name"]
except KeyError:
pass
try:
self.instance.ecf_code = self.cleaned_data["ecf_code"]
except KeyError:
pass
if commit:
self.instance.save()
return self.instance
I also do not have any default values for the Player model as the docs say the ModeForm will use these for values absent in the form submission.
EDIT:
Here is the whole EditPlayerForm:
class EditPlayerForm(forms.ModelForm):
class Meta:
model = Player
fields = ['first_name', 'last_name', 'ecf_code']
def __init__(self, *args, **kwargs):
super(EditPlayerForm, self).__init__(*args, **kwargs)
self.fields['first_name'].required = False
self.fields['last_name'].required = False
self.fields['ecf_code'].required = False
def save(self, commit = True):
# If I print instance variables here they've already
# been updated with the form values
self.cleaned_data = [ k for k,v in self.cleaned_data.items() if v ]
self.instance.save(update_fields = self.cleaned_data)
if commit:
self.instance.save()
return self.instance
EDIT:
Ok so here is the solution, I figured I'd put it here as it might be useful to other people (I've certainly learned a bit from this).
So it turns out that the is_valid() method of the model form actually makes the changes to the instance you pass into the form, ready for the save() method to save them. So in order to fix this problem, I extended the clean() method of the form:
def clean(self):
if not self.cleaned_data.get("first_name"):
self.cleaned_data["first_name"] = self.instance.first_name
if not self.cleaned_data.get("last_name"):
self.cleaned_data["last_name"] = self.instance.last_name
if not self.cleaned_data.get("ecf_code"):
self.cleaned_data["ecf_code"] = self.instance.ecf_code
This basically just checks to see if the fields are empty and if a field is empty, fill it with the existing value from the given instance. clean() gets called before the instance variables are set with the new form values, so this way, any empty fields were actually filled with the corresponding existing instance data.

You could maybe use the update() method instead of save()
or the argument update_field
self.instance.save(update_fields=['fields_to_update'])
by building the list ['fields_to_update'] only with the not empty values.
It should even work with the comprehension you've tried :
self.cleaned_data = [ k for k,v in self.cleaned_data.items() if v ]
self.instance.save(update_fields=self.cleaned_data)
EDIT :
Without overriding the save method (and commenting out this attempt in the form):
not_empty_data = [ k for k,v in edit_player_form.cleaned_data.items() if v ]
print(not_empty_data)
player = edit_player_form.save(update_fields=not_empty_data)

You could check the values if it's not empty in your view without overriding save()
if edit_player_form.is_valid():
if edit_player_form.cleaned_data["first_name"]:
selected_player.first_name = edit_player_form.cleaned_data["first_name"]
if edit_player_form.cleaned_data["last_name"]:
selected_player.last_name= edit_player_form.cleaned_data["last_name"]
if edit_player_form.cleaned_data["ecf_code"]:
selected_player.ecf_code= edit_player_form.cleaned_data["ecf_code"]
selected_player.save()
This should work fine with what you want. I'm not sure if it's the best way to do it but it should work fine.

Django custom Widget failing on choices above 1 (enter whole number)

I wanted a multiState clickbox. So I spend some free time on a nice Django solution that makes it:
class MultiStateChoiceInput(forms.widgets.ChoiceInput):
input_type = 'radio'
def __init__(self, name, value, attrs, choice, index, label_id):
# Override to use the label_id which is upped with 1
if 'id' in attrs:
self.label_id = attrs['id']+ "_%d" % label_id
super(MultiStateChoiceInput, self).__init__(name, value, attrs, choice, index)
self.value = force_text(self.value)
#property
def id_for_label(self):
return self.label_id
def render(self, name=None, value=None, attrs=None, choices=()):
if self.id_for_label:
label_for = format_html(' for="{}"', self.id_for_label)
else:
label_for = ''
attrs = dict(self.attrs, **attrs) if attrs else self.attrs
return format_html(
'{} <label{}>{}</label>', self.tag(attrs), label_for, self.choice_label
)
class MultiStateRenderer(forms.widgets.ChoiceFieldRenderer):
choice_input_class = MultiStateChoiceInput
outer_html = '<span class="cyclestate">{content}</span>'
inner_html = '{choice_value}{sub_widgets}'
def render(self):
"""
Outputs a <ul> for this set of choice fields.
If an id was given to the field, it is applied to the <ul> (each
item in the list will get an id of `$id_$i`).
# upgraded with the label_id
"""
id_ = self.attrs.get('id')
output = []
for i, choice in enumerate(self.choices):
choice_value, choice_label = choice
if isinstance(choice_label, (tuple, list)):
attrs_plus = self.attrs.copy()
if id_:
attrs_plus['id'] += '_{}'.format(i)
sub_ul_renderer = self.__class__(
name=self.name,
value=self.value,
attrs=attrs_plus,
choices=choice_label,
label_id = (i+1) % (len(self.choices)) # label_id is next one
)
sub_ul_renderer.choice_input_class = self.choice_input_class
output.append(format_html(self.inner_html, choice_value=choice_value,
sub_widgets=sub_ul_renderer.render()))
else:
w = self.choice_input_class(self.name, self.value,
self.attrs.copy(), choice, i, label_id = (i+1) % (len(self.choices))) # label_id is next one
output.append(format_html(self.inner_html,
choice_value=force_text(w), sub_widgets=''))
return format_html(self.outer_html,
id_attr=format_html(' id="{}"', id_) if id_ else '',
content=mark_safe('\n'.join(output)))
class MultiStateSelectWidget(forms.widgets.RendererMixin, forms.widgets.Select):
''' This widget enables multistate clickable toggles
Requires some css as well (see .cyclestate)
'''
renderer = MultiStateRenderer
This creates a form like is explained here https://stackoverflow.com/a/33455783/3849359 and where a click toggles the next state until it reached the and and then continues at the beginning.
The form is called in my view like:
SomeFormSet= modelformset_factory(myModel, form=myModelForm, extra=0)
SomeFormSet.form = staticmethod(curry(myModelForm, somevariable=somevariable))
formset = SomeFormSet(request.POST or None, queryset=somequeryset)
And forms.py is:
class myModelForm(forms.ModelForm):
CHOICES = (
(0, _('a')),
(1, _('b')),
(2, _('c')),
(3, _('d')),
)
field = forms.IntegerField(widget=MultiStateSelectWidget(choices=CHOICES))
class Meta:
model = MyModal
fields = ('field',)
widgets = {'id': forms.HiddenInput(),
}
def __init__(self, *args, **kwargs):
self.variable= kwargs.pop('variable')
super(myModelForm, self).__init__(*args, **kwargs)
for field in myModelForm.fields:
if self.instance.pk:
if not getattr(self.instance, field):
self.initial[field]= 0
else:
self.initial[field]= 1
if anothercondition:
self.initial[field] = 3
else:
self.initial[field] = 2
I thought it worked very well. And the clicking and saving does work wel (I have a custom save method). Except when the form field has a value of 2 or 3, then it suddenly failes with the error message: 'field' should be a whole number.
If anyone could help that would be great, as I'm out of ideas!
EDIT: Just in case... I have checked the POST and it is great. The only problem is that Django somewhere in parsing the POST loses the value completely (it becomes None) if the value is a 2 and I have no idea why.
EDIT2: It seems that the Django ModelForm does also do model validation. And the model is a BooleanField, which is the reason why it fails. If anyone knows a good way to override it, that would be nice!

#edgarzamora Your comment is not the answer, but it is close!
I removed the 'field' from the Form class Meta, so it looked like:
class Meta:
model = MyModal
fields = ('',)
widgets = {'id': forms.HiddenInput(),
}
And now everything works, because I have my custom save method... So stupid, it costed me hours! Thanks!

How to override a Model Form widget in Django?

I'm trying to override render_option method present inside Select Widget class from my forms.py file. So I have added the method with the same name inside the corresponding Model form class. But it won't work (this method fails to override). My forms.py file looks like,
class CustomSelectMultiple(Select):
allow_multiple_selected = True
def render_option(self, selected_choices, option_value, option_label):
print 'Inside custom render_option\n\n'
if option_value is None:
option_value = ''
option_value = force_text(option_value)
if option_value in selected_choices:
selected_html = mark_safe(' selected="selected"')
if not self.allow_multiple_selected:
# Only allow for a single selection.
selected_choices.remove(option_value)
else:
selected_html = ''
return format_html('<option value="{}" data-img-src="www.foo.com" {}>{}</option>',
option_value,
selected_html,
force_text(option_label))
def render_options(self, choices, selected_choices):
print 'Inside custom render_options\n\n'
print self
print choices
# Normalize to strings.
selected_choices = set(force_text(v) for v in selected_choices)
output = []
for option_value, option_label in chain(self.choices, choices):
if isinstance(option_label, (list, tuple)):
output.append(format_html('<optgroup label="{}">', force_text(option_value)))
for option in option_label:
output.append(self.render_option(selected_choices, *option))
output.append('</optgroup>')
else:
output.append(self.render_option(selected_choices, option_value, option_label))
#print output
return '\n'.join(output)
def render(self, name, value, attrs=None, choices=()):
print 'Inside custom render\n\n'
if value is None:
value = []
final_attrs = self.build_attrs(attrs, name=name)
output = [format_html('<select multiple="multiple"{}>', flatatt(final_attrs))]
options = self.render_options(choices, value)
if options:
output.append(options)
output.append('</select>')
return mark_safe('\n'.join(output))
def value_from_datadict(self, data, files, name):
if isinstance(data, MultiValueDict):
return data.getlist(name)
return data.get(name)
class GuideUpdateForm(ModelForm):
def __init__(self, *args, **kwargs):
super(GuideUpdateForm, self).__init__(*args, **kwargs)
self.fields['date_modified'].widget = HiddenInput()
self.fields['point_of_interest'].widget = CustomSelectMultiple()
class Meta:
fields = ('name', 'image', 'point_of_interest', 'date_modified', )
model = Guide
I also tried changing my Meta class like,
class Meta:
fields = ('name', 'image', 'point_of_interest', 'date_modified', )
model = Guide
widgets = {
'point_of_interest': SelectMultiple(attrs={'data-img-src': 'www.foo.com'}),
}
But it add's the attribute data-img-src only to the select tag but not to all the option tags present inside the select tag.
Note that SelectMultiple class invokes the renderoptions method of Select class which further invokes the renderoption method which don't have attrs=None keyword argument.

Judging off your own solution it looks like you may have been looking for a ModelChoiceField
self.fields['point_of_interest'] = forms.ModelChoiceField(widget=CustomSelectMultiple(),
queryset=poi.objects.all())
The queryset parameter consists of "A QuerySet of model objects from which the choices for the field will be derived, and which will be used to validate the user’s selection."
does it create a list of tuples of ids, names? Because I want the option tag to look like option value="id">name</option>
I'm pretty sure the default is id, __str__ where __str__ is the string representation of the model. If you wanted this to be specific to the name then you could override this field and set label_from_instance
class MyModelChoiceField(ModelChoiceField):
def label_from_instance(self, obj):
return obj.name

I managed to solve this problem by passing db values to choices kwargs.
from models import poi
class GuideUpdateForm(ModelForm):
def __init__(self, *args, **kwargs):
super(GuideUpdateForm, self).__init__(*args, **kwargs)
self.fields['date_modified'].widget = HiddenInput()
self.fields['point_of_interest'] = forms.ChoiceField(widget=CustomSelectMultiple(), choices=[(i.id,i.name) for i in poi.objects.all()])

Django form field widget becomes hidden

Model field links as foreign_key to another model which has big amount of entries.
I decided to replace default select for foreign_keys with simple link.
And it works grate besides the fact that field becomes hidden!
What should I do to avoid that?
admin.py
class SeriesAdmin(ModelLinkAdminFields, admin.ModelAdmin):
modellink = ['video',]
wdiget_file.py
class ModelLinkWidget(forms.HiddenInput):
def __init__(self, admin_site, original_object):
self.admin_site = admin_site
self.original_object = original_object
super(ModelLinkWidget,self).__init__()
def render(self, name, value, attrs=None):
if self.original_object is not None:
change_url = urlresolvers.reverse('admin:%s_%s_change' %
(type(self.original_object)._meta.app_label,
type(self.original_object)._meta.object_name.lower()),
args=(self.original_object.id,))
return mark_safe('<a id="%s" name="{name}" href="%s">%s</a>' %
(attrs['id'], change_url , escape(self.original_object)))
else:
return None
class ModelLinkAdminFields(object):
def get_form(self, request, obj=None, **kwargs):
form = super(ModelLinkAdminFields, self).get_form(request, obj, **kwargs)
if hasattr(self, 'modellink'):
for field_name in self.modellink:
if field_name in form.base_fields:
form.base_fields[field_name].widget = ModelLinkWidget(self.admin_site, getattr(obj, field_name, ''))
return form

Your widget overrides forms.HiddenInput
You should use the correct widget, I presume this should be Select but there are other options available

How to check object before adding 'inline = []' in Django

I don't know how to make one customization in my Django admin panel.
For example I have table test and another table testinfo. I know how to make admin.TabularInline of testinfo table in test table. But how to check, for example, if id of test table is bigger than 3, to show TabularInline, if not to not show?

ModelAdmin has a method called get_inline_instances() that can be used to achieve this effect.
class TestAdmin(admin.ModelAdmin):
def get_inline_instances(self, request, obj=None):
if obj.id > 3:
self.inlines = [TestInfoInline, ]
else:
self.inlines = []
return super(TestAdmin, self).get_inline_instances(request, obj)
Second example - the effect remains exactly the same:
class TestAdmin(admin.ModelAdmin):
inlines_foo = []
inlines_bar = [TestInfoInline, ]
def get_inline_instances(self, request, obj=None):
self.inlines = self.inlines_foo if obj.id <= 3 else self.inlines_bar
return super(TestAdmin, self).get_inline_instances(request, obj)

Well I think your problem is related to the issue discussed here Misleading documentation in ModelAdmin.get_inline_instances. So essentially your code should be changed to something like...
# Assuming you have a TestInfoInline inline that inherits from a BaseModelAdmin defined
# similarly to below.
class TestInfoInline(admin.StackedInline):
# Relevant stuff here...
...
class TestAdmin(admin.ModelAdmin):
def get_inline_instances(self, request, obj=None):
inlines = []
if obj.id > 3:
for inline_class in self.inlines:
# Instanciate inline object
inline = inline_class(self.model, self.admin_site)
inlines.append(inline)
return inlines
Hope this helps someone...