How to use ModelForm with neo4django? - django

This seems like a bug but I just want to make sure I'm consuming the API properly.
It seems that support for django's modelform isn't supported on neo4django. Here's what I have:
Simple class:
from neo4django.db import models
class Person(models.NodeModel):
name = models.StringProperty()
The modelform:
class PersonForm(forms.ModelForm):
class Meta:
model = Person
Will trigger exception:
'super' object has no attribute 'editable'
I posted details as an issue:
https://github.com/scholrly/neo4django/issues/135
Because when Django goes to lookup field information using the model's _meta information, it finds a BoundProperty instead of a StringProperty or Property (which has a member called 'editable', but BoundProperty doesn't).
Is there a workaround, or is this an actual bug? Any ideas on how to fix the bug? I'm not familiar with the library codebase.
Thanks!

Below is a reasonable (and quick) workaround for anyone using neo4j with Django.
This solution requires that field names on the form have the exact same name as the attributes of the model.
Inherit the form from this class and set the model under the form class Meta class:
class NeoModelForm(forms.Form):
def __init__(self, *args, **kwargs):
super(NeoModelForm, self).__init__(*args, **kwargs)
self._meta = getattr(self, 'Meta', None)
if not self._meta:
raise Exception('Missing Meta class on %s' % str(self.__class__.__name__))
if not hasattr(self._meta, 'model'):
raise Exception('Missing model on Meta class of %s' % str(self.__class__.__name__))
def save(self, commit=True):
if not self.is_valid():
raise Exception('Failed to validate')
instance = self._meta.model(**self.cleaned_data)
if commit:
instance.save()
return instance
Now you can create a form class like this:
class PersonForm(NeoModelForm):
name = forms.CharField(widget=forms.TextInput())
class Meta:
model = Person
And still be able to save a model instance from a valid form:
form = formclass(request.POST)
if form.is_valid():
obj = form.save()
Plus the commit argument will give you the same solution as django's modelform class- but I didn't bother to implement to save_m2m functionality (which doesn't seem relevant for neo4j as a backend).

Related

Getting a Model dynamic by knowing its name

I use Django 2.1.
I have a general utility/function(using celery) that I call from the save method of a Model(is an abstract Model, inherited by other Models).
Because the data from the function will be serialize, I pass to it the Model name and PK.
class A(models.Model)
def save(self, *args, **kwargs):
send_async(model_name=type(self).__name__, pk=self.id))
class B(A)
class C(A)
Later, I want to query the Model, but I don't know how to get the Model:
I tried:
model = apps.get_model('django_app_name.{}'.format(model_name))
I get the following error:
No installed app with label 'django_app_name'.
Also:
model = ContentType.objects.get(model=model_name)
This doesn't trow an error, but very strange behavior 'recalls' the View with different arguments, and off course no results.
Use the name of the app which has the model, not django_app_name.
To get the model name, try this:
send_async(model_name=self.__class__.__name__, pk=self.id)
instance.__class__.__name__ will return the class name
You should do like so:
class A(models.Model)
def save(self, *args, **kwargs):
send_async(
model_name=self._meta.model_name,
app_label=self._meta.app_label,
pk=self.id
)
And in send_async:
def send_async(model_name, app_label, pk):
content_type = ContentType.objects.get(app_label=app_label, model=model_name)
instance = content_type.get_object_for_this_type(id=pk)
...
For more information about it see https://docs.djangoproject.com/en/2.1/ref/contrib/contenttypes/

Custom error messages in Django Rest Framework serializer

The scenario is quite straight-forward:
I have a model with some fields that are required. Let's say one of them is a TextField which can't be blank.
I also have a ModelSerializer (Django Rest Framework) that represents that model.
When an empty string is used to set that field through the serializer the error returned comes from the model itself (This field can't be blank).
I would like to override the error messages only in the serializer level, without the need to explicitly re-specifying every field in the serializer (which I believe is against the DRY principle), having to write a validate_ method for each field and raise my own ValidationError or having to change the error messages in the Model level (because sometimes the context of the error message matters to my use-case and the error message should be given accordingly).
In other words, is there a way to override error messages in the serializer level as easy as it is for a ModelForm:
class MyModelForm(ModelForm):
class Meta:
model = MyModel
error_messages = {"field1": {"required": _("For some reason this is a custom error message overriding the model's default")}}
EDIT: I see that this question still receives some views, so it is important to note that there's another approach, much cleaner than the original answer I posted here.
You can just use the extra_kwargs attribute of the serializer's Meta class, like so:
class UserSerializer(ModelSerializer):
class Meta:
model = User
extra_kwargs = {"username": {"error_messages": {"required": "Give yourself a username"}}}
Original answer:
Using #mariodev 's answer I created a new class in my project that does that:
from rest_framework.serializers import ModelSerializer, ModelSerializerOptions
class CustomErrorMessagesModelSerializerOptions(ModelSerializerOptions):
"""
Meta class options for CustomErrorMessagesModelSerializerOptions
"""
def __init__(self, meta):
super(CustomErrorMessagesModelSerializerOptions, self).__init__(meta)
self.error_messages = getattr(meta, 'error_messages', {})
class CustomErrorMessagesModelSerializer(ModelSerializer):
_options_class = CustomErrorMessagesModelSerializerOptions
def __init__(self, *args, **kwargs):
super(CustomErrorMessagesModelSerializer, self).__init__(*args, **kwargs)
# Run through all error messages provided in the Meta class and update
for field_name, err_dict in self.opts.error_messages.iteritems():
self.fields[field_name].error_messages.update(err_dict)
The first one gives the possibility to add a new Meta class attribute to the serializer as with the ModelForm.
The second one inherits from ModelSerializer and uses #mariodev's technique to update the error messages.
All is left to do, is just inherit it, and do something like that:
class UserSerializer(CustomErrorMessagesModelSerializer):
class Meta:
model = User
error_messages = {"username": {"required": "Give yourself a username"}}
I tried to create a simple Serializer rather than a ModelSerializer. Probably because of that the accepted answer with extra_kwargs by Gabriel Amram didn't work for me. Another top answer by #mariodev did work but I was looking for a more elegant solution and found one. Turns out that the Field class accepts error_messages as a parameter, which is a dictionary that overrides the default error messages. Here is the reference to the docs. It's the same format as described in the accepted answers. Here is an example:
from rest_framework import serializers
class MySerializer(serializers.Serializer):
client_id = serializers.IntegerField(required=True, error_messages={'required': 'Custom error message'})
In your serializer:
class UserSerializer(serializers.ModelSerializer):
class Meta:
model = User
def __init__(self, *args, **kwargs):
super(UserSerializer, self).__init__(*args, **kwargs)
self.fields['username'].error_messages['required'] = u'My custom required msg'
Please notice that some error messages consist of %s placeholders like:
'invalid': _("'%s' value must be either True or False."),
for BooleanField.
So you need to go over default_error_messages part in each field type in the DRF's fields.py, to use it properly.
unique seemed to be ignored from error_messages, so I had to take a different approach.
email = serializers.EmailField(validators=[
UniqueValidator(
queryset=models.Client.objects.all(),
message="My custom error",
)]
)
It's simpler (yet less flexible, less reusable) than #gabriel-amram's, but far less hacky than #mariodev's.
Another approach for UniqueValidator (for using with ModelSerializer):
def __init__(self, *args, **kwargs):
super(UserSerializer, self).__init__(*args, **kwargs)
# Find UniqueValidator and set custom message
for validator in self.fields['email'].validators:
if isinstance(validator, validators.UniqueValidator):
validator.message = _('This email already exist on this site')
I just spent an hour ripping my hair out over this, so figured I'd post an update here in case anyone else finds it useful.
I'm using djangorestframework version 3.10.3, and for whatever reason, it seems that drf no longer uses the 'required' key in the error_messages dict to allow customization of an error message for a missing value. Instead it uses 'blank'.
class SampleSerializer(serializers.HyperlinkedModelSerializer):
class Meta:
model = SampleModel
fields = (
'description',
)
extra_kwargs = {
'description': {'error_messages': {'blank': "Please provide a description"}},
}
DRF3.0 expects us to explicitly define the validators for fields if we wish to override the default model validators. This can be done by passing extra_kwargs and explicitly defining the validators for whichever field
you seem necessary. Also you can even specify your own custom validator which can be reused again for different fields or even other serializers
http://www.django-rest-framework.org/api-guide/serializers/#validation
http://www.django-rest-framework.org/api-guide/validators/#validation-in-rest-framework
# my_app/validators.py
def validate_required(value):
# whatever validation logic you need
if value == '' or value is None:
raise serializers.ValidationError('This field is required.')
# my_app/serializers.py
class MyModelSerializer(serializers.ModelSerializer):
class Meta:
model = MyModel
extra_kwargs = {"field1": {"validators": [validators.validate_required,]}}
Just a note since I played with this for awhile, if you're using something like a URLField that just adds a URLValidator, it doesn't seem to use the error_messages, so I did something similar to #Hugo's answer:
class Meta:
extra_kwargs = {"url_field": {"validators": [validators.URLValidator(message="My error message")]}}
You can create separate function in serializers.py and call it from serializer class
def checkFields(fields):
for field in fields:
fields[field].error_messages['blank']=fields[field].error_messages['required'] = 'Please enter %s'%field
This is the code that inherits the model's error message.
There is also a module, so download it if you want.
If there's a problem, leave it in the comments.
https://pypi.org/project/django-rest-inherits-error-messages/#files
from rest_framework import serializers
from rest_framework.relations import HyperlinkedRelatedField
from rest_framework.utils.field_mapping import get_nested_relation_kwargs
class InheritsModelSerializer(serializers.ModelSerializer):
def build_field(self, field_name, info, model_class, nested_depth):
'''
inherits the error_messages of the model
'''
result: tuple = super().build_field(field_name, info, model_class, nested_depth)
field = model_class._meta.get_field(field_name)
error_messages = field.error_messages
if error_messages:
result[1]['error_messages'] = field.error_messages
return result

Access model instance from model field

I want my Django custom model field to set an attribute on the model instance.
I'm sure it's not working this way but here is an example:
class MyField(models.Field):
__metaclass__ = models.SubfieldBase
def __init__(self, *args, **kwargs):
super(MyField, self).__init__(*args, **kwargs)
model_instance = ????
setattr(model_instance, "extra_attribute", "It's working!")
class MyModel(models.Model):
my_field = MyField()
model_instance = MyModel.objects.get(pk=123)
print model_instance.extra_attribute # output: "It's working!"
Django's ForeignKey model field is doing a similar thing, so it is possible :P
I think ForeignKey field is using the contribute_to_class method.
You can create a special Proxy class that will replace the field. When getting or setting field value, you can use 'obj' attribute to access model instance. See this example:
class ObjectField(models.PositiveSmallIntegerField):
class ObjectProxy:
def __init__(self, field):
self.field = field
def __get__(self, obj, model):
if obj is None:
return self.field # this is required for initializing model field
value = obj.__dict__[self.field.name] # get actual field value
# ... here you can do something with value and model instance ("obj")
return value
def __set__(self, obj, value):
# same here
obj.__dict__[self.field.name] = value
def contribute_to_class(self, cls, name):
super().contribute_to_class(cls, name)
# set up our proxy instead of usual field
setattr(cls, name, ObjectField.ObjectProxy(self))
You do not have access to the model instance from inside your Field object, sorry. Django's ForeignKey accomplishes the foo_id thing by having separate name and attname fields, but the actual setting of foo_id = 123 is done the same way as all the other model fields, deep in the QuerySet code, without interacting with the field classes.
And conceptually, what you're trying to do is a bad idea - action-at-a-distance. What if adding a particular field could cause bugs in unrelated model functionality, say, if an attribute another field was expecting got overridden? It would be difficult to debug, to say the least. I don't know what your underlying goal is, but it should probably be done in model code, not a field class.
Here's a ModelField that does what you want:
https://gist.github.com/1987190
That's actually pretty old (like maybe pre-1.0, don't remember now), had to dust it off a bit - I'm not sure if it still works. But it's definitely doable, hopefullly this gives you an idea.
init is called when Django processes the Model Class, not the Model Instance. So, you can add the attribute to the Model Class (e.g. by using 'add_to_class' http://www.alrond.com/en/2008/may/03/monkey-patching-in-django/ ). To add the attribute to the instance you should override the init of the instance (but I think this is not your case).
How about
model_instance = SomeExtraModel.objects.get(pk=1456)
replacing 1456 with something that makes sense

Django Problem inheriting formfield_callback in ModelForms

I've only been using Django for a couple of weeks now, so I may be approaching this all kinds of wrong, but:
I have a base ModelForm that I put some boilerplate stuff in to keep things as DRY as possible, and all of my actual ModelForms just subclass that base form. This is working great for error_css_class = 'error' and required_css_class = 'required' but formfield_callback = add_css_classes isn't working like I would expect it to.
forms.py
# snippet I found
def add_css_classes(f, **kwargs):
field = f.formfield(**kwargs)
if field and 'class' not in field.widget.attrs:
field.widget.attrs['class'] = '%s' % field.__class__.__name__.lower()
return field
class BaseForm(forms.ModelForm):
formfield_callback = add_css_classes # not working
error_css_class = 'error'
required_css_class = 'required'
class Meta:
pass
class TimeLogForm(BaseForm):
# I want the next line to be in the parent class
# formfield_callback = add_css_classes
class Meta(BaseForm.Meta):
model = TimeLog
The end goal is to slap some jquery datetime pickers on forms with a class of datefield/timefield/datetimefield. I want all of the date time fields within the app to use the same widget, so I opted to do it this way than explicitly doing it for each field in every model. Adding an extra line to each form class isn't that big of a deal, but it just bugged me that I couldn't figure it out. Digging around in the django source showed this is probably doing something I'm not understanding:
django.forms.models
class ModelFormMetaclass(type):
def __new__(cls, name, bases, attrs):
formfield_callback = attrs.pop('formfield_callback', None)
But I don't know how __init__ and __new__ are all intermangled. In BaseForm I tried overriding __init__ and setting formfield_callback before and after the call to super, but I'm guessing it needs to be somewhere in args or kwargs.
__new__ is called before object construction. Actually this is a factory method that returns the instance of a newly constructed object.
So there there are 3 key lines in ModelFormMetaclass:
formfield_callback = attrs.pop('formfield_callback', None) #1
fields = fields_for_model(opts.model, opts.fields,
opts.exclude, opts.widgets, formfield_callback) #2
new_class.base_fields = fields #3
In the class we attach base_fields to our form.
Now let's look to ModelForm class:
class ModelForm(BaseModelForm):
__metaclass__ = ModelFormMetaclass
This means that ModelFormMetaclass.__new__(...) will be called when we create a ModelForm instance to change the structure of the future instance. And attrs of __new__ (def __new__(cls, name, bases, attrs)) in ModelFormMetaclass is a dict of all attributes of ModelForm class.
So decision is to create new InheritedFormMetaclass for our case (inheriting it from ModelFormMetaclass). Don't forget to call new of the parent in InheritedFormMetaclass. Then create our BaseForm class and say:
__metaclass__ = InheritedFormMetaclass
In __new__(...) implementation of InheritedFormMetaclass we could do all we want.
If my answer is not detailed enough please let me know with help of comments.
You may set widgets class like this:
class TimeLogForm(BaseForm):
# I want the next line to be in the parent class
# formfield_callback = add_css_classes
class Meta(BaseForm.Meta):
model = TimeLog
widgets = {
'some_fields' : SomeWidgets(attrs={'class' : 'myclass'})
}
For what you're trying to accomplish, I think you're better off just looping through the fields on form init. For example,
class BaseForm(forms.ModelForm):
def __init__(self, *args, **kwargs):
super(BaseForm, self).__init__(*args, **kwargs)
for name, field in self.fields.items():
field.widget.attrs['class'] = 'error'
Clearly you'll need a little more logic for your specific case. If you want to use the approach that sergzach suggested (overkill for your particular problem I think), here's some code for you that will call formfield_callback on the base class in the case the subclass doesn't define it.
baseform_formfield_callback(field):
# do some stuff
return field.formfield()
class BaseModelFormMetaclass(forms.models.ModelFormMetaclass):
def __new__(cls, name, bases, attrs):
if not attrs.has_key('formfield_callback'):
attrs['formfield_callback'] = baseform_formfield_callback
new_class = super(BaseModelFormMetaclass, cls).__new__(
cls, name, bases, attrs)
return new_class
class BaseModelForm(forms.ModelForm):
__metaclass__ = OrganizationModelFormMetaclass
# other form stuff
Finally, you might wanna look into crispy forms: https://github.com/maraujop/django-crispy-forms
sergzach is correct that you have to use metaclasses; overriding __init__ is not enough. The reason is that the metaclass for ModelForm (which will be called for all ModelForm subclasses unless you specify another metaclass in a subclass) takes the class definition, and using the values in the class definition creates a class with class attributes. For example, both META.fields and our formfield_callback is used to create form Fields with various option (like which widget).
That means AFAIU formfield_callback is a parameter to the metaclass used when creating your custom model form class, not some value used at runtime when actual form instances are created. That makes placing formfield_callback in __init__ useless.
I solved a similiar problem with a custom metaclass like
from django.forms.models import ModelFormMetaclass
class MyModelFormMetaclass(ModelFormMetaclass):
def __new__(cls,name,bases,attrs):
attrs['formfield_callback']=my_callback_function
return super(MyModelFormMetaclass,cls).__new__(cls,name,bases,attrs)
and in the base class for all my model forms setting the metaclass
class MyBaseModelForm(ModelForm):
__metaclass__=MyModelFormMetaclass
...
which can be used like (at least in Django 1.6)
class MyConcreteModelForm(MyBaseModelForm):
# no need setting formfield_callback here
...

Free-form input for ForeignKey Field on a Django ModelForm

I have two models related by a foreign key:
# models.py
class TestSource(models.Model):
name = models.CharField(max_length=100)
class TestModel(models.Model):
name = models.CharField(max_length=100)
attribution = models.ForeignKey(TestSource, null=True)
By default, a django ModelForm will present this as a <select> with <option>s; however I would prefer that this function as a free form input, <input type="text"/>, and behind the scenes get or create the necessary TestSource object and then relate it to the TestModel object.
I have tried to define a custom ModelForm and Field to accomplish this:
# forms.py
class TestField(forms.TextInput):
def to_python(self, value):
return TestSource.objects.get_or_create(name=value)
class TestForm(ModelForm):
class Meta:
model=TestModel
widgets = {
'attribution' : TestField(attrs={'maxlength':'100'}),
}
Unfortunately, I am getting: invalid literal for int() with base 10: 'test3' when attempting to check is_valid on the submitted form. Where am I going wrong? Is their and easier way to accomplish this?
Something like this should work:
class TestForm(ModelForm):
attribution = forms.CharField(max_length=100)
def save(self, commit=True):
attribution_name = self.cleaned_data['attribution']
attribution = TestSource.objects.get_or_create(name=attribution_name)[0] # returns (instance, <created?-boolean>)
self.instance.attribution = attribution
return super(TestForm, self).save(commit)
class Meta:
model=TestModel
exclude = ('attribution')
There are a few problems here.
Firstly, you have defined a field, not a widget, so you can't use it in the widgets dictionary. You'll need to override the field declaration at the top level of the form.
Secondly get_or_create returns two values: the object retrieved or created, and a boolean to show whether or not it was created. You really just want to return the first of those values from your to_python method.
I'm not sure if either of those caused your actual error though. You need to post the actual traceback for us to be sure.
TestForm.attribution expects int value - key to TestSource model.
Maybe this version of the model will be more convenient for you:
class TestSource(models.Model):
name = models.CharField(max_length=100, primary_key=True)
Taken from:
How to make a modelform editable foreign key field in a django template?
class CompanyForm(forms.ModelForm):
s_address = forms.CharField(label='Address', max_length=500, required=False)
def __init__(self, *args, **kwargs):
super(CompanyForm, self).__init__(*args, **kwargs)
try:
self.fields['s_address'].initial = self.instance.address.address1
except ObjectDoesNotExist:
self.fields['s_address'].initial = 'looks like no instance was passed in'
def save(self, commit=True):
model = super(CompanyForm, self).save(commit=False)
saddr = self.cleaned_data['s_address']
if saddr:
if model.address:
model.address.address1 = saddr
model.address.save()
else:
model.address = Address.objects.create(address1=saddr)
# or you can try to look for appropriate address in Address table first
# try:
# model.address = Address.objects.get(address1=saddr)
# except Address.DoesNotExist:
# model.address = Address.objects.create(address1=saddr)
if commit:
model.save()
return model
class Meta:
exclude = ('address',) # exclude form own address field
This version sets the initial data of the s_address field as the FK from self, during init , that way, if you pass an instance to the form it will load the FK in your char-field - I added a try and except to avoid an ObjectDoesNotExist error so that it worked with or without data being passed to the form.
Although, I would love to know if there is a simpler built in Django override.