Save and update json data to django models - django

I have a simple model Class
class Talk(models.Model):
url = models.URLField()
user = models.ForeignKey(User)
category = models.ForeignKey(Category)
description = models.TextField(blank=True, max_length=500)
title = models.TextField(blank=True)
and I connect to oembed api to get data from the url submitted
def get_oembed_info(self):
params = {'url': self.url, 'format': 'json'}
fetch_url = 'http://api.embed.ly/1/oembed?%s' % urllib.urlencode(params)
result = urllib.urlopen(fetch_url).read()
result = json.loads(result)
KEYS = ['title', 'type', 'url', 'description', 'provider_url', 'provider_name', 'width', 'height', 'html', 'thumbnail_url', 'author_url']
for key in KEYS:
if result.has_key(key):
setattr(self, key, result[key])
def save(self):
self.get_oembed_info()
super(Talk, self).save()
It's ok to add a new Talk from Admin but when i try to update the same talk later nothing changes.
Also is this way a good to get the data and store it in DB.
Thanks

Each time you save, you fetch data from the server and overwrite your model fields. You could check whether it's a new object before fetching:
def save(self, *args, **kwargs):
if not self.pk:
self.get_oembed_info()
super(Talk, self).save(*args, **kwargs)

Related

REST Django - How to Modify a Serialized File Before it is Put Into Model

I am hoping that I can find a way to resize an uploaded image file before it is put into the database.
I am new to Django with REST, so I am not sure how this would be done. It seems that whatever is serialized is just kind of automatically railroaded right into the model. Which I suppose is the point (it's certainly an easy thing to setup).
To clarify, I already have a function tested and working that resizes the image for me. That can be modified as needed and is no problem for me. The issue really is about sort of "intercepting" the image, making my changes, and then putting it into the model. Could someone help me out with some ideas of tactics to get that done? Thanks.
The Model:
class Media(models.Model):
objects = None
username = models.ForeignKey(User, to_field='username',
related_name="Upload_username",
on_delete=models.DO_NOTHING)
date = models.DateTimeField(auto_now_add=True)
media = models.FileField(upload_to='albumMedia', null=True)
file_type = models.CharField(max_length=12)
MEDIA_TYPES = (
('I', "Image"),
('V', "Video")
)
media_type = models.CharField(max_length=1, choices=MEDIA_TYPES, default='I')
user_access = models.CharField(max_length=1, choices=ACCESSIBILITY, default='P')
class Meta:
verbose_name = "MediaManager"
The View with post method:
class MediaView(APIView):
queryset = Media.objects.all()
parser_classes = (MultiPartParser, FormParser)
permission_classes = [permissions.IsAuthenticated, ]
serializer_class = MediaSerializer
def post(self, request, *args, **kwargs):
user = self.request.user
print(user.username)
request.data.update({"username": user.username})
media_serializer = MediaSerializer(data=request.data)
# media_serializer.update('username', user.username)
if media_serializer .is_valid():
media_serializer.save()
return Response(media_serializer.data, status=status.HTTP_201_CREATED)
else:
print('error', media_serializer.errors)
return Response(media_serializer.errors,status=status.HTTP_400_BAD_REQUEST)
The Serializer:
class MediaSerializer(serializers.ModelSerializer):
class Meta:
model = Media
fields = '__all__'
def to_representation(self, instance):
data = super(MediaSerializer, self).to_representation(instance)
return data
You can use validate method to validate and/or change the values from data dictionary.
class MediaSerializer(serializers.ModelSerializer):
...
def validate(self, data):
value_from_form = data['value_from_form']
value_from_form = 'Something else'
data['value_from_form'] = value_from_form
return data

Django: Remove form fileds based on some values in the database

I want to remove some fields from a form based on some values in the database. I'm not using this form to insert the data into any database, I'm going to make a csv file from this form data. Also this form is not related to any model.
forms.py
class Registration_form(forms.Form):
Applicant_Name = forms.CharField(label='Your name', max_length=100)
Applicant_age = forms.IntegerField(label ='Age of Applicant')
Applicant_email =forms.EmailField(max_length=50)
Applicant_phone = forms.CharField(max_length=10)
views.py
class Registration_View(FormView):
template_name = 'EVENTAPP/Application.html'
form_class = Registration_form
success_url = '/'
def form_valid(self, form):
Applicant_Name = form.cleaned_data['Applicant_Name'],
Applicant_age=form.cleaned_data['Applicant_age'],
Applicant_email=form.cleaned_data['Applicant_email']
Applicant_phone=form.cleaned_data['Applicant_phone']
# do some operations if form data valid
return super().form_valid(form)
models.py
class es_event(models.Model):
ev_name = models.CharField(max_length=100,verbose_name="Event Name")
ev_date = models.DateField(auto_now=False, verbose_name="Date")
ev_description = models.TextField(null=True, verbose_name="Description")
registrant_name = models.BooleanField(default=True )
registrant_age = models.BooleanField(default=False)
registrant_phone = models.BooleanField(default=False)
registrant_email = models.BooleanField(default=False)
registrant_institution = models.BooleanField(default=False)
name = models.CharField(max_length=100,null=True)
reg_open = True
slug = models.SlugField(max_length=250)
def save(self, *args, **kwargs):
self.slug = slugify(self.ev_name)
return super(es_event, self).save(*args, **kwargs)
def get_absolute_url(self):
return reverse('event_detail', kwargs={'id': self.id, 'slug': self.slug })
urls.py
url(r'^events/register(?P<id>\d+)(?:/(?P<slug>[\w\d-]+))?/$', views.Registration_View.as_view(), name='event_application')
Now what I want to do is find a particular instance of es_event from the database by using the value of "id" in the URL.
Then if that instance has the attributes registrant_name,registrant_age, etc is True then the fields Applicant_Name, Applicant_age, etc will be available on the form
You can use AJAX for that. I think this is an example similar to yours, just that instead of checking if the user exists, you check if your instance has desired attributes (registrant_name, registrant_age). And when you get JSON response you show/hide fields with Javascript.

Custom Django FileField url widget won't upload any file in admin change_form

I have a Files table with information about uploaded files in a remote directory. This is the model for that table:
class Files(models.Model):
id = models.AutoField(primary_key=True)
subjectid = models.ForeignKey('Subjects', models.DO_NOTHING, db_column='subjectid')
filetypeid = models.ForeignKey(FileTypes, models.DO_NOTHING, db_column='filetypeid')
filedescid = models.ForeignKey(FileDescription, models.DO_NOTHING, db_column='filedescid')
filepath = models.CharField(max_length=45, blank=True, null=True)
filename = models.FileField(upload_to='attachments/', blank=True, null=True)
ispublic = models.IntegerField(choices=YESNO)
extra_info = models.CharField(max_length=255, blank=True, null=True)
def __str__(self):
return self.filename.name or ''
class Meta:
managed = False
db_table = 'files'
verbose_name_plural = 'files'
I've created my own URL widget to replace the Django FileField url shown as 'Currently:' in the change_form template. The link points to a view that downloads the file. So far, so good it works but the problem is that when I try to add a new file I can select the new file with the Browse file button but when I click on Save the field filename field is empty and no file is uploaded.
class MyAdminURLFieldWidget(URLInput):
template_name = 'admin/widgets/url.html'
def __init__(self, attrs=None):
#final_attrs = {'class': 'vURLField'}
final_attrs = {'type': 'file'}
if attrs is not None:
final_attrs.update(attrs)
super(MyAdminURLFieldWidget, self).__init__(attrs=final_attrs)
def get_context(self, name, value, attrs):
context = super(MyAdminURLFieldWidget, self).get_context(name, value, attrs)
context['current_label'] = _('Currently:')
context['change_label'] = _('Change:')
context['widget']['href'] = smart_urlquote('/DownloadView/' + str(value.instance.id) + '/attachment/') if value else ''
return context
class FilesAdmin(admin.ModelAdmin):
list_display = ('id', '_animalid', '_filename', '_filedesc', 'ispublic', 'extra_info')
search_fields = ('subjectid__animalid','filename')
list_per_page = 50
def formfield_for_dbfield(self, db_field, **kwargs):
if db_field.name == 'filename':
request = kwargs.pop("request", None)
kwargs['widget'] = MyAdminURLFieldWidget
return db_field.formfield(**kwargs)
else:
return super(FilesAdmin, self).formfield_for_dbfield(db_field, **kwargs)
def _animalid(self, obj):
return obj.subjectid.animalid
def _filename(self, obj):
return obj.filename.name
def _filedesc(self, obj):
return obj.filedescid.description
Can anybody tell what I'm missing here?
Hi lost Django community,
I will answer my own question since it seems that nobody was able to realize the answer. It happens that as newbie I'm following examples I've found here and there but there is little about sub-classing the FileField associated widget. So, after diving deep into the Django code I've found the answer. In my case the problem was I derived my MyAdminURLFieldWidget from URLInput instead of the correct subclass ClearableFileInput.
You are welcome.

This QueryDict instance is immutable

I have a Branch model with a foreign key to account (the owner of the branch):
class Branch(SafeDeleteModel):
_safedelete_policy = SOFT_DELETE_CASCADE
name = models.CharField(max_length=100)
account = models.ForeignKey(Account, null=True, on_delete=models.CASCADE)
location = models.TextField()
phone = models.CharField(max_length=20, blank=True,
null=True, default=None)
create_at = models.DateTimeField(auto_now_add=True, null=True)
update_at = models.DateTimeField(auto_now=True, null=True)
def __str__(self):
return self.name
class Meta:
unique_together = (('name','account'),)
...
I have a Account model with a foreign key to user (one to one field):
class Account(models.Model):
_safedelete_policy = SOFT_DELETE_CASCADE
name = models.CharField(max_length=100)
user = models.OneToOneField(User)
create_at = models.DateTimeField(auto_now_add=True)
update_at = models.DateTimeField(auto_now=True)
def __str__(self):
return self.name + ' - ' + self.create_at.strftime('%Y-%m-%d %H:%M:%S')
I've created a ModelViewSet for Branch which shows the branch owned by the logged in user:
class BranchViewSet(viewsets.ModelViewSet):
serializer_class = BranchSerializer
permission_classes = (permissions.IsAuthenticated,)
def get_queryset(self):
queryset = Branch.objects.all().filter(account=self.request.user.account)
return queryset
Now to create a new branch, I want to save account field with request.user.account, not with data sent from the rest client (for more security). for example:
def create(self, request, *args, **kwargs):
if request.user.user_type == User.ADMIN:
request.data['account'] = request.user.account
return super(BranchViewSet, self).create(request, *args, **kwargs)
def perform_create(self, serializer):
'''
Associate branch with account
'''
serializer.save(account=self.request.user.account)
In branch serializer
class BranchSerializer(serializers.ModelSerializer):
account = serializers.CharField(source='account.id', read_only=True)
class Meta:
model = Branch
fields = ('id', 'name', 'branch_alias',
'location', 'phone', 'account')
validators = [
UniqueTogetherValidator(
queryset=Branch.objects.all(),
fields=('name', 'account')
)
]
but I got this error:
This QueryDict instance is immutable. (means request.data is a immutable QueryDict and can't be changed)
Do you know any better way to add additional fields when creating an object with django rest framework?
As you can see in the Django documentation:
The QueryDicts at request.POST and request.GET will be immutable when accessed in a normal request/response cycle.
so you can use the recommendation from the same documentation:
To get a mutable version you need to use QueryDict.copy()
or ... use a little trick, for example, if you need to keep a reference to an object for some reason or leave the object the same:
# remember old state
_mutable = data._mutable
# set to mutable
data._mutable = True
# сhange the values you want
data['param_name'] = 'new value'
# set mutable flag back
data._mutable = _mutable
where data it is your QueryDicts
Do Simple:
#views.py
from rest_framework import generics
class Login(generics.CreateAPIView):
serializer_class = MySerializerClass
def create(self, request, *args, **kwargs):
request.data._mutable = True
request.data['username'] = "example#mail.com"
request.data._mutable = False
#serializes.py
from rest_framework import serializers
class MySerializerClass(serializers.Serializer):
username = serializers.CharField(required=False)
password = serializers.CharField(required=False)
class Meta:
fields = ('username', 'password')
request.data._mutable=True
Make mutable true to enable editing in querydict or the request.
I personally think it would be more elegant to write code like this.
def create(self, request, *args, **kwargs):
data = OrderedDict()
data.update(request.data)
data['account'] = request.user.account
serializer = self.get_serializer(data)
serializer.is_valid(raise_exception=True)
self.perform_create(serializer)
headers = self.get_success_headers(serializer.data)
return Response(serializer.data, status=status.HTTP_201_CREATED, headers=headers)
Do you know any better way to add additional fields when creating an object with django rest framework?
The official way to provide extra data when creating/updating an object is to pass them to the serializer.save() as shown here
https://docs.djangoproject.com/en/2.0/ref/request-response/#querydict-objects
The QueryDicts at request.POST and request.GET will be immutable when accessed in a normal request/response cycle. To get a mutable version you need to use QueryDict.copy().
You can use request=request.copy() at the first line of your function.

Django rest framework get or create for PrimaryKeyRelatedField

I start to create REST API for my web-application with Django and Django rest framework and I need one logic problem.
There are entities Instruction and Tag. The user visit my service and create self Instruction and add exists Tag OR new Tag for it.
I created my model seriallizer class with using PrimaryKeyRelatedField for relation Instruction<->Tag. But if I do POST for a new Instruction with new Tag I got error: "Invalid pk \"tagname\" - object does not exist.".
I solved this problem with the overriding of the to_internal_value method in my field class.
What is the best practice for solving this problem? It seems to me this problem is typical for web and REST API.
My models:
class Tag(Model):
name = CharField(max_length=32, verbose_name=_("Name"),
unique=True, validators=[alphanumeric], primary_key=True)
def __str__(self):
return self.name
class Instruction(Model):
user = ForeignKey(settings.AUTH_USER_MODEL,
related_name='instructions',
on_delete=CASCADE,
blank=False, null=False,
verbose_name=_("User"))
title = CharField(max_length=256,
verbose_name=_("Title"),
blank=False, null=False)
created_datetime = DateTimeField(verbose_name=_("Creation time"), editable=False)
modified_datetime = DateTimeField(
verbose_name=_("Last modification time"), blank=False, null=False)
tags = ManyToManyField(Tag,
related_name="instructions",
verbose_name=_("Tags"))
class Meta:
ordering = ['-created_datetime']
# singular_name = _("")
def save(self, force_insert=False, force_update=False, using=None,
update_fields=None):
n = now()
if self.id is None:
self.created_datetime = n
self.modified_datetime = n
super(Instruction, self).save(force_insert, force_update, using, update_fields)
def __str__(self):
return self.title
my serializers:
class TagSerializer(serializers.ModelSerializer):
class Meta:
model = Tag
fields = ('name',)
class InstructionSerializer(serializers.ModelSerializer):
tags = PrimaryKeyCreateRelatedField(many=True, queryset=Tag.objects.all())
author = serializers.SerializerMethodField()
def get_author(self, obj):
return obj.user.username
class Meta:
model = Instruction
fields = ('id', 'user', 'title', 'created_datetime', 'modified_datetime', 'tags', 'author')
read_only_fields = ('modified_datetime',)
I created new field class class PrimaryKeyCreateRelatedField and overrided to_internal_value method for creating the new Tag object instead raising with message 'does_not_exist':
PrimaryKeyCreateRelatedField(serializers.PrimaryKeyRelatedField):
def to_internal_value(self, data):
if self.pk_field is not None:
data = self.pk_field.to_internal_value(data)
try:
return self.get_queryset().get(pk=data)
except ObjectDoesNotExist:
# self.fail('does_not_exist', pk_value=data)
return self.get_queryset().create(pk=data)
except (TypeError, ValueError):
self.fail('incorrect_type', data_type=type(data).__name__)
my view:
class InstructionViewSet(viewsets.ModelViewSet):
queryset = Instruction.objects.all()
serializer_class = InstructionSerializer
permission_classes = (permissions.IsAuthenticatedOrReadOnly,)
def create(self, request, *args, **kwargs):
data = dict.copy(request.data)
data['user'] = self.request.user.pk
serializer = InstructionSerializer(data=data)
if serializer.is_valid():
serializer.save()
return Response(serializer.data, status=status.HTTP_201_CREATED)
return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
Update
models.py
alphanumeric = RegexValidator(r'^[0-9a-zA-Z]*$',
_('Only alphanumeric characters are allowed.'))
class Tag(Model):
name = CharField(max_length=32, verbose_name=_("Name"),
unique=True, validators=[alphanumeric], primary_key=True)
def __str__(self):
return self.name
class Step(PolymorphicModel):
instruction = ForeignKey(Instruction,
verbose_name=_("Instruction"),
related_name='steps',
blank=False, null=False,
on_delete=CASCADE)
position = PositiveSmallIntegerField(verbose_name=_("Position"), default=0)
description = TextField(verbose_name=_("Description"),
max_length=2048,
blank=False, null=False)
class Meta:
verbose_name = _("Step")
verbose_name_plural = _("Steps")
ordering = ('position',)
unique_together = ("instruction", "position")
def __str__(self):
return self.description[:100]
class Instruction(Model):
user = ForeignKey(settings.AUTH_USER_MODEL,
related_name='instructions',
on_delete=CASCADE,
blank=False, null=False,
verbose_name=_("User"))
title = CharField(max_length=256,
verbose_name=_("Title"),
blank=False, null=False)
created_datetime = DateTimeField(verbose_name=_("Creation time"), editable=False)
modified_datetime = DateTimeField(
verbose_name=_("Last modification time"), blank=False, null=False)
tags = ManyToManyField(Tag,
related_name="instructions",
verbose_name=_("Tags"))
# thumbnail = #TODO: image field
class Meta:
ordering = ['-created_datetime']
# singular_name = _("")
def save(self, force_insert=False, force_update=False, using=None,
update_fields=None):
n = now()
if self.id is None:
self.created_datetime = n
self.modified_datetime = n
super(Instruction, self).save(force_insert, force_update, using, update_fields)
def __str__(self):
return self.title
views.py
class InstructionViewSet(viewsets.ModelViewSet):
queryset = Instruction.objects.all()
permission_classes = (permissions.IsAuthenticatedOrReadOnly,)
def get_serializer_class(self):
"""Return different serializer class for different action."""
if self.action == 'list':
return InstructionSerializer
elif self.action == 'create':
return InstructionCreateSerializer
serialiers.py
class PrimaryKeyCreateRelatedField(serializers.PrimaryKeyRelatedField):
def to_internal_value(self, data):
if self.pk_field is not None:
data = self.pk_field.to_internal_value(data)
try:
return self.get_queryset().get(pk=data)
except ObjectDoesNotExist:
# self.fail('does_not_exist', pk_value=data)
return self.get_queryset().create(pk=data)
except (TypeError, ValueError):
self.fail('incorrect_type', data_type=type(data).__name__)
class InstructionCreateSerializer(serializers.ModelSerializer):
tags = PrimaryKeyCreateRelatedField(many=True, queryset=Tag.objects.all())
steps = InstructionStepSerializer(many=True)
user = serializers.HiddenField(default=serializers.CurrentUserDefault())
class Meta:
model = Instruction
fields = ('id', 'user', 'title', 'created_datetime', 'modified_datetime', 'tags', 'steps')
read_only_fields = ('modified_datetime',)
def create(self, validated_data):
tags_data = validated_data.pop('tags')
steps_data = validated_data.pop('steps')
# NOTE: tags need add after creation of the Instruction object otherwise we will got exception:
# "needs to have a value for field "id" before this many-to-many relationship can be used."
instruction = Instruction.objects.create(**validated_data)
for tag in tags_data:
instruction.tags.add(tag)
for step in steps_data:
Step.objects.create(instruction=instruction,
description=step['description'],
position=step['position'])
return instruction
class InstructionSerializer(serializers.ModelSerializer):
tags = serializers.StringRelatedField(many=True)
author = serializers.SerializerMethodField()
steps = InstructionStepSerializer(many=True)
def get_author(self, obj):
return obj.user.username
class Meta:
model = Instruction
fields = ('id', 'user', 'title', 'created_datetime', 'modified_datetime', 'tags', 'author', 'steps')
read_only_fields = ('modified_datetime',)
In my case to solve the problem I need to override the method run_validation. That allow make check of tags and create their (if not exists) before validation.
class InstructionCreateSerializer(serializers.ModelSerializer):
steps = InstructionStepSerializer(many=True)
user = serializers.HiddenField(default=serializers.CurrentUserDefault())
class Meta:
model = Instruction
fields = ('title', 'created_datetime', 'modified_datetime', 'tags', 'steps', 'id', 'user')
read_only_fields = ('modified_datetime',)
def run_validation(self, data=serializers.empty):
if 'tags' in data:
for tag in data['tags']:
Tag.objects.get_or_create(name=tag)
return super(InstructionCreateSerializer, self).run_validation(data)
def create(self, validated_data):
tags_data = validated_data.pop('tags')
steps_data = validated_data.pop('steps')
# NOTE: tags need add after creation of the Instruction object otherwise we will got exception:
# "needs to have a value for field "id" before this many-to-many relationship can be used."
instruction = Instruction.objects.create(**validated_data)
for tag in tags_data:
instruction.tags.add(tag)
for step in steps_data:
Step.objects.create(instruction=instruction,
description=step['description'],
position=step['position'])
return instruction
Apart from the answers given by #YPCrumble and #SijanBhandari, I just had to comment on something in your code.
In the models.py, you have overridden the save method for adding created_at and modified_on. For that you could just add
created_at = models.DateTimeField(auto_now_add=True)
modified_on = DateTimeField (auto_now=True)
The auto_now_add option sets when the object is created for the first time.
It's not editable. The auto_now setting sets whenever the object is saved, ie, whenever object.save() method is called upon.
These usually are used for timestamping the objects for future references.
Why write so many lines, when you could do this on just 2 lines of code.
Just a heads up though!!
For further details, go to the documentation here
In "regular" Django you usually want to create your model instance in the form's save method, not the view. DRF is similar, in that you want to create your model instances in the serializer's create or update methods. The reason for this is that if you need to add a new endpoint to your API you can reuse the serializer and would not have to write duplicate code creating or updating your model instance.
Here's how I'd refactor your code:
Remove the entire create method from your ModelViewSet - you don't need to override that.
Remove the custom PrimaryKeyCreateRelatedField - you just need a PrimaryKeyRelatedField
Add two methods to your serializer - create and update:
In the create method, create your tag objects before saving the instruction object like you can see in the DRF docs. You can get the current user like you were doing in your view via self.context['request'].user in this create method. So you might create the Instruction like Instruction.objects.create(user=self.context['request'].user, **validated_data) and then loop through the tags (like they do for tracks in the docs) to add them to the Instruction.
The docs don't have an example update method but essentially your update method also takes an instance parameter for the existing instruction. See this answer from the creator of DRF for more details
The best way would be sort out everything at your CREATE method of the view.
I believe you tags will be sent from your front-end to the back-end at the format of
[ 1,
{'name': "TEST"},
{'name': 'TEST2'}
]
Here '1' is the existing tag id and 'TEST' and 'TEST2' are the two new tags inserted by
the user. Now you can change your CREATE method as follows:
class InstructionViewSet(viewsets.ModelViewSet):
queryset = Instruction.objects.all()
serializer_class = InstructionSerializer
permission_classes = (permissions.IsAuthenticatedOrReadOnly,)
def create(self, request, *args, **kwargs):
data = dict.copy(request.data)
data['user'] = self.request.user.pk
# MODIFICATION.....
tags = self.request.get('tags', None)
tag_list = []
if tags:
for tag in tags:
if isinstance(tag, dict):
new_tag = Tag.objects.create(name=tag['name'])
tag_list.append(new_tag.id)
else:
tag_list.append(int(tag))
data = {
'title': ....
'tags': tag_list,
'user': ...
'author': ...
......
}
serializer = InstructionSerializer(data=data)
I hope it will be helpful for you.