i have a model, like this:
name = models.CharField(max_length=255)
modify_time = models.DateTimeField(auto_now=True)
chasha = models.CharField(max_length=255)
stat = models.CharField(max_length=255)
Usually, 'modify_time' will be updated when i update 'name', 'chasha', 'stat' field. But, I just did not want the 'modify_time' been updated when i update 'stat'. how can i do that?
thanks.
Use a custom save method to update the field by looking at a previous instance.
from django.db import models
from django.utils import timezone as tz
class MyModel(models.Model):
name = models.CharField(max_length=255)
modify_time = models.DateTimeField(null=True, blank=True)
chasha = models.CharField(max_length=255)
stat = models.CharField(max_length=255)
def save(self, *args, **kwargs):
if self.pk: # object already exists in db
old_model = MyModel.objects.get(pk=self.pk)
for i in ('name', 'chasha'): # check for name or chasha changes
if getattr(old_model, i, None) != getattr(self, i, None):
self.modify_time = tz.now() # assign modify_time
else:
self.modify_time = tz.now() # if new save, write modify_time
super(MyModel, self).save(*args, **kwargs) # call the inherited save method
Edit: remove auto_now from modify_time like above, otherwise it will be set at the save method.
Related
I am trying to implement a CSV Import in Django Admin and save bulk data corresponding to the CSV file's rows.
This is my Admin class:
class EmployeeAdmin(admin.ModelAdmin):
list_display = ('user', 'company', 'department', 'designation', 'is_hod', 'is_director')
search_fields = ['user__email', 'user__first_name', 'user__last_name']
form = EmployeeForm
This is my Form class:
class EmployeeForm(forms.ModelForm):
company = forms.ModelChoiceField(queryset=Companies.objects.all())
file_to_import = forms.FileField()
class Meta:
model = Employee
fields = ("company", "file_to_import")
def save(self, commit=True, *args, **kwargs):
try:
company = self.cleaned_data['company']
records = csv.reader(self.cleaned_data['file_to_import'])
for line in records:
# Get CSV Data.
# Create new employee.
employee = CreateEmployee(...)
except Exception as e:
raise forms.ValidationError('Something went wrong.')
My Employee class is:
class Employee(models.Model):
user = models.OneToOneField(User, primary_key=True)
company = models.ForeignKey(Companies)
department = models.ForeignKey(Departments)
mobile = models.CharField(max_length=16, default="0", blank=True)
gender = models.CharField(max_length=1, default="m", choices=GENDERS)
image = models.ImageField(upload_to=getImageUploadPath, null=True, blank=True)
designation = models.CharField(max_length=64)
is_hod = models.BooleanField(default=False)
is_director = models.BooleanField(default=False)
When I upload my file and click save, it shows me this error:
'NoneType' object has no attribute 'save'
with exception location at:
/usr/local/lib/python2.7/dist-packages/django/contrib/admin/options.py in save_model, line 1045
EDIT I understand I need to put a call to super.save, but I am unable to figure out where to put the call, because the doc says that the save method saves and returns the instance. But in my case, there is no single instance that the superclass can save and return. Wham am I missing here?
TIA.
You should just add the super().save() to the the end of the function:
def save(self, *args, commit=True, **kwargs):
try:
company = self.cleaned_data['company']
records = csv.reader(self.cleaned_data['file_to_import'])
for line in records:
# Get CSV Data.
# Create new employee.
employee = CreateEmployee(...)
super().save(*args, **kwargs)
except Exception as e:
raise forms.ValidationError('Something went wrong.')
I'm playing around in Django, and wondering if there is a way to loop through instances of two different models I have created?
/ models.py:
class Tran(models.Model):
name = models.CharField(max_length=300)
description = models.CharField(max_length=2000)
type = models.ForeignKey(TransactionType)
def __str__(self):
return self.name
class DocLink(models.Model):
trann = models.ForeignKey(Transaction)
t_link = models.CharField(max_length=2000)
t_display = models.CharField(max_length=1000)
p_display = models.CharField(max_length=300)
p_link = models.CharField(max_length=2000)
def __str__(self):
return self.link
What I want to do:
Look through each of the Tran instances and create a default value for the links/displays in the DocLink table instead of doing it manually.
Is there anyway I can be pointed in the right direction?
If you want to set links/displays default value in DocLink instance based on trann field you can override model's save method.
For example following code shows how to set t_link if it doesn't have a value:
class DocLink(models.Model):
trann = models.ForeignKey(Transaction)
t_link = models.CharField(max_length=2000)
t_display = models.CharField(max_length=1000)
p_display = models.CharField(max_length=300)
p_link = models.CharField(max_length=2000)
def __str__(self):
return self.link
def save(self, *args, **kwargs):
if not self.t_link:
pass # TODO set self.t_link based on trann
super(DocLink, self).save(*args, **kwargs)
Also you can change model's trann field to:
trann = models.ForeignKey(Transaction, related_name="doclinks")
And then access to all DocLinks of a Tran with:
# t is an instance of Tran class
t.doclinks.all()
So you can loop through this list and do what you want.
taking my initial lessons with django ModelForm ,I wanted to give the user ,ability to edit an entry in a blog.The BlogEntry has a date,postedTime, title and content.I want to show the user an editform which shows all these fields,but with only title and content as editable. The date and postedTime should be shown as uneditable.
class BlogEntry(models.Model):
title = models.CharField(unique=True,max_length=50)
description = models.TextField(blank=True)
date = models.DateField(default=datetime.date.today)
postedTime = models.TimeField(null=True)
...
For adding an entry ,I use a ModelForm in the normal way..
class BlogEntryAddForm(ModelForm):
class Meta:
model = BlogEntry
...
But how do I create the edit form?I want it to show the date,postedTime as uneditable (but still show them on the form) and let the user edit the title and description.
if I use,exclude in class Meta for date and postedTime,that will cause them not to appear on the form.So,how can I show them as uneditable?
class BlogEntryEditForm(ModelForm):
class Meta:
model = BlogEntry
...?...
In the form object, declare the attribute of the field as readonly:
form.fields['field'].widget.attrs['readonly'] = True
Is date field represent a date when the entry first created or when it was modified last time? If first then use auto_now_add option else use auto_now. That is:
date = models.DateField(auto_now_add=True)
will set date to now when entry will be created.
auto_now_add makes field uneditable. For other cases use editable option to make any field uneditable. For example
postedDate = models.TimeField(null=True, editable=False)
Also, likely you will add posted boolean field to Entry model, so it is convinient to set auto_now on postedDate. It will set postedDate to now every time you modify a Entry including one when you set posted to True.
I implemented it this way: https://djangosnippets.org/snippets/10514/
this implementation uses the data of model instance for all read-only fields and not the data obtained while processing the form
below the same code but using his example
from __future__ import unicode_literals
from django.utils import six
from django.utils.encoding import force_str
__all__ = (
'ReadOnlyFieldsMixin',
'new_readonly_form_class'
)
class ReadOnlyFieldsMixin(object):
"""Usage:
class MyFormAllFieldsReadOnly(ReadOnlyFieldsMixin, forms.Form):
...
class MyFormSelectedFieldsReadOnly(ReadOnlyFieldsMixin, forms.Form):
readonly_fields = ('field1', 'field2')
...
"""
readonly_fields = ()
def __init__(self, *args, **kwargs):
super(ReadOnlyFieldsMixin, self).__init__(*args, **kwargs)
self.define_readonly_fields(self.fields)
def clean(self):
cleaned_data = super(ReadOnlyFieldsMixin, self).clean()
for field_name, field in six.iteritems(self.fields):
if self._must_be_readonly(field_name):
cleaned_data[field_name] = getattr(self.instance, field_name)
return cleaned_data
def define_readonly_fields(self, field_list):
fields = [field for field_name, field in six.iteritems(field_list)
if self._must_be_readonly(field_name)]
map(lambda field: self._set_readonly(field), fields)
def _all_fields(self):
return not bool(self.readonly_fields)
def _set_readonly(self, field):
field.widget.attrs['disabled'] = 'true'
field.required = False
def _must_be_readonly(self, field_name):
return field_name in self.readonly_fields or self._all_fields()
def new_readonly_form_class(form_class, readonly_fields=()):
name = force_str("ReadOnly{}".format(form_class.__name__))
class_fields = {'readonly_fields': readonly_fields}
return type(name, (ReadOnlyFieldsMixin, form_class), class_fields)
Usage:
class BlogEntry(models.Model):
title = models.CharField(unique=True,max_length=50)
description = models.TextField(blank=True)
date = models.DateField(default=datetime.date.today)
postedTime = models.TimeField(null=True)
# all fields are readonly
class BlogEntryReadOnlyForm(ReadOnlyFieldsMixin, forms.ModelForm):
class Meta:
model = BlogEntry
# selected fields are readonly
class BlogEntryReadOnlyForm2(ReadOnlyFieldsMixin, forms.ModelForm):
readonly_fields = ('date', 'postedTime')
class Meta:
model = BlogEntry
or use the function
class BlogEntryForm(forms.ModelForm):
class Meta:
model = BlogEntry
BlogEntryFormReadOnlyForm = new_readonly_form_class(BlogEntryForm, readonly_fields=('description', ))
This will prevent any user from hacking the request:
self.fields['is_admin'].disabled = True
Custom form example:
class MemberShipInlineForm(forms.ModelForm):
is_admin = forms.BooleanField(required=False)
def __init__(self, *args, **kwargs):
super(MemberShipInlineForm, self).__init__(*args, **kwargs)
if 'instance' in kwargs and kwargs['instance'].is_group_creator:
self.fields['is_admin'].disabled = True
class Meta:
model = MemberShip
fields = '__all__'
From the documentation,
class BlogEntryEditForm(ModelForm):
class Meta:
model = BlogEntry
readonly_fields = ['date','postedTime']
I have a situation where I want to use the Meta options of unique_together to enforce a certain rule, here's the intermediary model:
class UserProfileExtension(models.Model):
extension = models.ForeignKey(Extension, unique=False)
userprofile = models.ForeignKey(UserProfile, unique=False)
user = models.ForeignKey(User, unique=False)
class Meta:
unique_together = (("userprofile", "extension"),
("user", "extension"),
# How can I enforce UserProfile's Client
# and Extension to be unique? This obviously
# doesn't work, but is this idea possible without
# creating another FK in my intermediary model
("userprofile__client", "extension"))
and here's UserProfile:
class UserProfile(models.Model):
user = models.ForeignKey(User, unique=True)
client = models.ForeignKey(Client)
Thanks.
You can't.
The unique_together clause is directly translated to the SQL unique index. And you can only set those on columns of a single table, not a combination of several tables.
You can add validation for it yourself though, simply overwrite the validate_unique method and add this validation to it.
Docs: http://docs.djangoproject.com/en/dev/ref/models/instances/#django.db.models.Model.validate_unique
My 2 cents, complementing the accepted response from #Wolph
You can add validation for it yourself though, simply overwrite the validate_unique method and add this validation to it.
This is a working example code someone could find usefull.
from django.core.exceptions import ValidationError
class MyModel(models.Model):
fk = models.ForeignKey(AnotherModel, on_delete=models.CASCADE)
my_field = models.CharField(...) # whatever
def validate_unique(self, *args, **kwargs):
super().validate_unique(*args, **kwargs)
if self.__class__.objects.\
filter(fk=self.fk, my_field=self.my_field).\
exists():
raise ValidationError(
message='MyModel with this (fk, my_field) already exists.',
code='unique_together',
)
My solution was to use Django's get_or_create. By using get_or_create, a useless get will occur if the row already exists in the database, and the row will be created if it does not exist.
Example:
extension = Extension.objects.get(pk=someExtensionPK)
userProfile = UserProfile.objects.get(pk=someUserProfilePK)
UserProfileExtension.objects.get_or_create(extension=extension, userprofile=userProfile)
From django 2.2+ versions, it is suggested to use constraint & Index as model class meta option:
https://docs.djangoproject.com/en/3.2/ref/models/options/#django.db.models.Options.unique_together
https://docs.djangoproject.com/en/3.2/ref/models/options/#django.db.models.Options.constraints
class UniqueConstraintModel(models.Model):
race_name = models.CharField(max_length=100)
position = models.IntegerField()
global_id = models.IntegerField()
fancy_conditions = models.IntegerField(null=True)
class Meta:
constraints = [
models.UniqueConstraint(
name="unique_constraint_model_global_id_uniq",
fields=('global_id',),
),
models.UniqueConstraint(
name="unique_constraint_model_fancy_1_uniq",
fields=('fancy_conditions',),
condition=models.Q(global_id__lte=1)
),
models.UniqueConstraint(
name="unique_constraint_model_fancy_3_uniq",
fields=('fancy_conditions',),
condition=models.Q(global_id__gte=3)
),
models.UniqueConstraint(
name="unique_constraint_model_together_uniq",
fields=('race_name', 'position'),
condition=models.Q(race_name='example'),
)
]
You need to call Models.full_clean() method to call validate_unique for foreignKey. You can override save() to call this
class UserProfileExtension(models.Model):
extension = models.ForeignKey(Extension, unique=False)
userprofile = models.ForeignKey(UserProfile, unique=False)
user = models.ForeignKey(User, unique=False)
def save(self, *args, **kwargs):
self.full_clean()
super().save(*args, **kwargs)
class Meta:
unique_together = (("userprofile", "extension"),
("user", "extension"),
# How can I enforce UserProfile's Client
# and Extension to be unique? This obviously
# doesn't work, but is this idea possible without
# creating another FK in my intermediary model
("userprofile__client", "extension"))
from django.core.exceptions import ValidationError
.....
class UserProfileExtension(models.Model):
extension = models.ForeignKey(Extension, unique=False)
userprofile = models.ForeignKey(UserProfile, unique=False)
user = models.ForeignKey(User, unique=False)
def validate_unique(self, *args, **kwargs):
super(UserProfileExtension, self).validate_unique(*args, **kwargs)
query = UserProfileExtension.objects.filter(extension=self.extension)
if query.filter(userprofile__client=self.userprofile.client).exists():
raise ValidationError({'extension':['Extension already exits for userprofile__client',]})
The first query is to filter all records in UserProfileExtension model which has the same extension we are putting in the current record.
Then we filter the query returned to find if it already contains userprofile__client which we are passing in the current record.
Another possible solution is to add this on your save method from your Model:
def save(self, *args, **kwargs):
unique = self.__class__.objects.filter( extension =self.extension, userprofile=self.userprofile )
if unique.exists():
self.id = unique[0].id
super(self.__class__, self).save(*args, **kwargs)
I just started to learn Django and I had a question.
I'm trying to automatically add the missing information, when saving form data. I get to change/add the desired "cleaned_data" information by overriding save() method of modelform class, but changes are not recorded in the database. Actually, how to write the modified information? This is code:
def save(self, commit = True, *args, **kwargs):
temp = ServiceMethods(url = self.cleaned_data.get('url'), wsdl_url = self.cleaned_data.get('wsdl_url'))
if not temp.get_wsdl_url():
temp.make_wsdl_url()
if temp.get_wsdl_url():
temp.make_wsdl()
self.cleaned_data['wsdl_url'] = temp.get_wsdl_url()
self.cleaned_data['wsdl_description'] = temp.get_wsdl_description()
super(ServiceForm, self).save(commit = commit, *args, **kwargs)
And model:
class Services(models.Model):
name = models.CharField('Имя', max_length=256)
url = models.URLField('Ссылка', unique = True)
wsdl_url = models.URLField('Ссылка на WSDL-документ', blank=True)
description = models.TextField('Описание сервиса',blank=True)
wsdl_description = models.TextField('WSDL описание', blank=True, editable=False)
added = models.DateTimeField('Добавлено', auto_now_add=True)
TIA
Try setting the data on self.instance instead of in self.cleaned_data, and let me know if that works.