I have a table called 'users' and 'location'. Users table has a foreign key that relates to location table. I have a users serializer to get the JSON. What would I do to get the hyperlinks for the users table using its primary key?
In django rest framework documentation, I couldn't find a solution. I tried using hyperlinkrelatedfield. But still I couldn't achieve this. Can someone help me in finding the solution?
Using rest-framework HyperlinkedRelatedField does not work because it was never built to expose the URL of the object being requested. Mainly because since the client already has the url of the user, why send it back again? Nevertheless you can achieve this by doing something like this.
class UserSerializer(serializers.ModelSerializer):
user_url = serializers.SerializerMethodField()
class Meta:
model = User
def get_label_location(self, obj):
return HyperlinkedRelatedField(view_name='user-detail',
read_only=True) \
.get_url(obj, view_name='label-detail',
request=self.context['request'], format=None)
Take note on a few things,
view-name param to the HyperlinkedRelatedField should be based on your url configuration
read-only has to be true since otherwise you'll have to specify the queryset. But since we have the object needed to generate the url we can ignore that.
I've set format param to None but you might want to set it based on your settings.
You can read up about SerializerMethodField here.
Related
I have a model
class SomeModel(models.Model):
emails = ArrayField(models.EmailField(), default=list)
And let's say I have the following Serializer of the model:
class SomeModelSerializer(serializers.ModelSerializer):
class Meta:
model = SomeModel
fields = ['emails']
The email field is not blank-able, i.e: It's required to set a value for it when submitting a Form of the model, or when making changes to its Admin page.
My understanding is that DRF relies as well on Django's internal machinery to validate whether emails is missing on the Serializer data or not. But the thing is that I can't find where (and when) this happens.
I've found that DRF is not calling the Model's clean() method anymore (link). But what baffles me is that changing the blank value on the field seems to have a direct impact on the Serializer. I have switched to blank=True, and then the Serializer would allow it to be saved without that field... Then I switched back to blank=False, and the Serializer would fail if emails is not present.
So do you have any idea of when and where DRF checks for a field's blank value?
Thanks!
As far as I know, it simply doesn't. Those are only used across forms and the django admin interface.
I always specify those things on the serializer level, by setting the appropiate arguments for my fields (doc), in this case it would be allow_blank.
I am building REST APIs with django, and the only case where the blank property on the model field catches me, is when fiddling around on the admin page.
However, there appears to be a package that could be of interest to you:
django-seriously.
I haven't used it, but it appears to call full_clean() on every save().
Of course, this has the disadvantage that you will probably loose DRFs nice error messages.
I am creating an app with a rest API that should return values for instances of objects based on the url given. Right now I have the API working using ModelViewSets of my objects for the API.
For example I have three objects, user, transactions, and goals.
As it stands I can go to /mysite/api/users and return a list of all users
I can also go to /mysite/api/users/1 to return just the user with the id '1'.
I can do something similar with transactions and goals.
What I'm looking to do is go to url /mysite/api/users/1/transaction/1/goal
to find the goal associated with the transaction for that user.
I've been scouring tutorials and am not sure what the right question is to ask in order to find something useful to learn how to do this. What is the correct way to go about setting up my rest api like this?
If I understand correctly, you want to create nested ressources.
If you are using Viewsets, then the ExtendedRouter class of the drf-extensions package will allow you to achieve this.
Drf-extensions documentation about this feature: https://chibisov.github.io/drf-extensions/docs/#nested-routes
There is also this module, who also offer the same features.
You can either use url params or query params to solve your issue. I will explain the URL params solution here,
serializers.py
#Write a Goal Serializer
urls.py
#change the URL according to your environment
url(r'^users/(?P<uid>[0-9]+)/transaction/(?P<tid>[0-9]+)/goal/$', GoalViewSet.as_view({'get': 'user_transaction_goal',}), name='user-transaction-goal'),
views.py
class GoalViewSet(viewsets.ModelViewSet):
permission_classes = [IsAuthenticated]
queryset = Goal.objects.all()
def user_transaction_goal(self, request, uid, tid):
#assuming user is FK in transaction and transaction is a FK in goal
#modify the filter rule according to your model design
goals = Goal.objects.filter(transaction=tid, transaction__user=uid)
serializer = GoalSerializer(goals, many=False)
return Response(serializer.data)
As #clement mentioned you can also use plugins to handle this situation.
I have large table of data (~30 Mb) that I converted into into a model in Django. Now I want to have access to that data through a REST API.
I've successfully installed the Django REST framework, but I'm looking for a way to automatically create a URL for each field in my model. My model has about 100 fields, and each field has about 100,000 entries.
If my model is named Sample,
models.py
class Sample(models.Model):
index = models.IntegerField(primary_key=True)
year = models.IntegerField(blank=True, null=True)
name = models.TextField(blank=True, null=True)
...97 more fields...
then I can access the whole model using Django REST framework like this:
urls.py
class SampleSerializer(serializers.HyperlinkedModelSerializer):
class Meta:
model = Sample
fields = ( **100 fields**)
class SampleViewSet(viewsets.ModelViewSet):
queryset = Sample.objects.all()
serializer_class = SampleSerializer
router = routers.DefaultRouter()
router.register(r'sample', SampleViewSet)
But of course my browser can't load all of that data in a reasonable amount of time. I could manually make a different class and URL for each field, but there must be a better way... I want to be able to go to my_site.com/sample/year (for example) and have it list all of the years in JSON format, or my_site.com/sample/name and list all the names, etc.
Please help me figure out how to do this, thanks!
You might be able to do that using a custom viewset route.
You have this:
class ModelViewSet(ModelViewSet):
#list_route()
def sample_field(self, request):
desired_field = request.data.get('field', None)
if not desired_field:
return response # pseudocode
values = Model.objects.all().values_list(desired_field, flat=True)
# serialize this for returning the response
return Response(json.dumps(values)) # this is an example, you might want to do something mode involved
You will be able to get this from the url:
/api/model/sample_field/?field=foo
This extra method on the viewset will create a new endpoint under the samples endpoint. Since it's a list_route, you can reach it using /sample_field.
So following your code, it would be:
mysite.com/sample/sample_field/?field='year'
for example.
There are many interesting details in your question, but with this sample I think you might able to achieve what you want.
Try to use pagination. You can do it in almost the same way as in you question. Pagination in django lets you divide the results into pages. You don't have to display all the entries in the same page. I think this is the best option for you.
Refer django documentation on pagination:
Pagination in django
I am building a web app using Django that is pretty much only serving as the API server. I have a single-page application that connects to it as well as an Android client. I have a need to modify some of the incoming POST requests that are coming through.
My two use cases:
If during the registration process the user does not select an avatar image to upload (which is a simple TextField that is the URL to the image), I should be able to insert the default avatar URL. So something like if request.data["avatar"] is None: <use default>
The incoming "timestamp" requests from the Android client are all unix timestamps. I would like to convert this to Django's datetime on the fly - so, current request comes in with date_time = 1473387225, I'd like to convert that to a DateTime object.
Now, I'm already doing something similar for certain POST parameters. The way I do it right now is in the post() function of my generic ListCreateApiView I would directly modify the request object and then call the self.create() with that new request object. Is this the right way, or is there a much better way to do it?
Thanks!
If you are using django-rest-framework these things can be done by serializers.
For avatar use an URLField with default value.
For the timestamp you should probably create a custom field.
Check out this site: http://www.cdrf.co It is an easily navigable display of all the methods available on a given class. You can simply use this to overwrite the View you are using. If a model ViewSet, you likely want perform_create and perform_update.
I often do something like this:
class SomeViewSet(viewsets.ModelViewSet):
queryset = SomeModel.objects.all()
serializer_class = SomeModelSerializer
def perform_create(self, serializer):
data = self.request.data
# make some changes to self.request here
serializer.save(
#change some things here
field='some new value'
)
You can do this in a number of ways. As a part of your validation or in the to_internal_value of the request serializer or in a custom field serializer.
Heres an example of doing this as a part of a custom field serializer.
class AccountCreationSerializer(serializers.Serializer):
avatar = AvatarField(
required=False
allow_files=True
)
# Custom Field Serializer
class AvatarField(serializers.FilePathField):
def to_internal_value(self, value):
user_defined_path = super(AvatarField, self).to_internal_value(value)
if user_defined_path:
return user_defined_path
return default_path
I have a table 'Comments' and inside field the 'user', I would get in addition to the profile Profile in the same query. Currently I have something like that
comments = models.Comment.objects.select_related('author__profile').filter(post=article)
Unfortunately I can not retrieve information about profile, I can only get to it through
comment.author._profile_set_cache
Any ideas to make it look nice like?
comment.author.profile
If the 'author' is from the contrib.auth User model, then you don't have a FK to the UserProfile. It is a "reverse one-to-one". Fortunately, django is able to navigate a reverse one-to-one using "select_related", so the query is actually retrieving the fields (you can check it by using
print models.Comment.objects.select_related('author__profile').filter(post=article).query
The way to get the profile of a user is with the get_profile() method:
print comment.author.get_profile()
As the profile data is already cached (that's why the _profile_set_cache is for), getting the object means no additional query.