I have a querySet that I want to turn into a json and send to the client.
It only needs some of the fields, as defined.
However, the 'sender' shows up as a id because it is a foreignKey.
What would be needed to return the senders username instead? (sender.username didn't work). (Not using drf)
messages = Message.objects.all()
messages_json = serializers.serialize("json", messages, fields=('id','sender', 'text', 'timestamp'))
Not tested but using QuerySet.values and __ relations-walking lets you get the data in one hit:
import json
messages = Message.objects.all()
payload_data = messages.values('id', 'sender__username', 'text', 'timestamp')
# tidy up the dict key names, assuming the client needs that doing
for x in payload_data:
x['sender'] = x['sender__username']
del x['sender__username']
messages_json = json.dumps(payload_data)
I think I've found a way so I'll answer it myself
from django.core.serializers.python import Serializer
class MySerialiser(Serializer):
def end_object( self, obj ):
self._current['username'] = obj.sender.username
self.objects.append(self._current)
serializer = MySerialiser()
messages_ser = serializer.serialize(messages, fields=('id','sender','text' ))
messages_json = json.dumps(messages_ser)
messages_ser is a orderedDict, so turning it into json only works when there are no nested objects/dicts
Related
What i am trying to do is to nest a DRF model serializer into another model serialiser's field like so
class username_serial(ModelSerializer):
class Meta:
model = User
fields = ['username','email']
class game_serial(ModelSerializer):
user_01 = username_serial()
class Meta:
model = game
fields = ['id','user_01','user_02','is_private','is_accepted']
Error :
Exception inside application: You cannot call this from an async
context - use a thread or sync_to_async. Traceback (most recent call
last): File
"C:\Users\baza\Desktop\production\venv\lib\site-packages\django\db\models\fields\related_descriptors.py",
line 173, in get
rel_obj = self.field.get_cached_value(instance) File "C:\Users\baza\Desktop\production\venv\lib\site-packages\django\db\models\fields\mixins.py",
line 15, in get_cached_value
return instance._state.fields_cache[cache_name] KeyError: 'user_01'
This works normally without Django Chennels because channels is async and i can't use sync code with, works fine by using:
os.environ["DJANGO_ALLOW_ASYNC_UNSAFE"] = "true"
In the settings file but it's not a safe approach when it comes to production.
i tried using channel's database_sync_to_async as a decorator and as well as a function with a SerializerMethodField like so:
class game_serial(ModelSerializer):
user_01 = SerializerMethodField(read_only=True)
#database_sync_to_async
def get_user_01(self, obj):
username = obj.user_01.username
return str(username)
class Meta:
model = game
fields = ['id','user_01','user_02','is_private','is_accepted']
but i get back:
[OrderedDict([('id', 23), ('user_01', <coroutine object SyncToAsync.__call__ at 0x0000000005DF6678>), ('user_02', None), ('is_private', False), ('is_accepted', False)]), OrderedDict([('id', 24), ('user_01', <coroutine object SyncToAsync.__call__ at 0
x0000000005DF6D58>), ('user_02', None), ('is_private', False), ('is_accepted', False)])]
with an
Exception inside application: Object of type 'coroutine' is not JSON
serializable
so i guess that JSON couldn't serialize those "coroutine" objects and normally i should or "want" to get the actual values of them instead.
How can i do the task? any workaround or other methods are welcomed, thank you in advance.
in consumers.py ..
games = await database_sync_to_async(self.get_games)()
serialized_games = game_serial(games, many=True)
await self.send({
"type": "websocket.send",
'text': json.dumps(serialized_games.data)
})
def get_games(self):
return list(game.objects.all())
I never used Django Channels but I know Django and async.
I'll be honest, I don't like these hacky decorators. And I don't think running such a simple task in a thread is a good idea.
You have an obj, so you were able to query the DB earlier. If so, there's a place without async context or async context where accessing the DB works. In the error message user_01 is not found in the "cached" object from the DB. So just prefetch what you need before.
def get_queryset(self):
return game_serial.objects.select_related('user_01')
class game_serial(ModelSerializer):
user_01 = serializers.CharField(source='user_01.username')
This way you don't have problems with this sync-to-async magic, it's more efficient and easier to reason about.
EDIT:
I repeat, you should select related where you fetch the data. After you added another example, I can suggest something like that
def get_games(self):
return list(game.objects.select_related('user_01').all())
and it will work just fine.
You can also try
#database_sync_to_async
def get_games(self):
return list(game.objects.select_related('user_01').all())
and
serialized_games = await game_serial(games, many=True)
In both cases this serializer will work just fine.
class game_serial(ModelSerializer):
user_01 = serializers.CharField(source='user_01.username')
class Meta:
model = game
fields = ['id','user_01','user_02','is_private','is_accepted']
I need to change the view of the error displayed when I validate the field.
serializer.py
class ElementCommonInfoSerializer(serializers.ModelSerializer):
self_description = serializers.CharField(required=False, allow_null=True,
validators=[RegexValidator(regex=r'^[a-zA-Z0-9,.!? -/*()]*$',
message='The system detected that the data is not in English. '
'Please correct the error and try again.')]
)
....
class Meta:
model = Elements
fields = ('self_description',......)
This error is displayed
{
"self_description": [
"The system detected that the data is not in English. Please correct the error and try again."
]
}
The key of error dict is field name - self_description. For FE I need to send another format like:
{
"general_errors": [
"The system detected that the data is not in English. Please correct the error and try again."
]
}
How to change this?
One way this could be achieved is via custom exception handler
from copy import deepcopy
from rest_framework.views import exception_handler
def genelalizing_exception_handler(exc, context):
# Call REST framework's default exception handler first,
# to get the standard error response.
response = exception_handler(exc, context)
# Now add the HTTP status code to the response.
if 'self_description' in response.data:
data = deepcopy(response.data)
general_errors = data.pop('self_description')
data['general_errors'] = general_errors
response.data = data
return response
in settings
REST_FRAMEWORK = {
'EXCEPTION_HANDLER': 'my_project.my_app.utils. genelalizing_exception_handler'
}
Another solution is to rewrite the validate method.
def validate(self, data):
self_description = str((data['self_description']))
analyst_notes = str((data['analyst_notes']))
if re.match(r'^[a-zA-Z0-9,.!? -/*()]*$', self_description) or re.match(r'^[a-zA-Z0-9,.!? -/*()]*$', analyst_notes):
raise serializers.ValidationError({
"general_errors": [
"The system detected that the data is not in English. Please correct the error and try again."
]
})
return data
The solution is very simple.
you can rename the key field by using serializer method (source attribute)
below you can find an example code.
class QuestionSerializer(serializers.ModelSerializer):
question_importance = serializers.IntegerField(source='importance')
question_importance = serializers.IntegerField(required=False)
class Meta:
model = create_question
fields = ('id','question_importance','complexity','active')
Above you can see I have an importance field which is present in django model But here I renamed this field to question_importance by using source attribute .
In your case it will be like below,
class ElementCommonInfoSerializer(serializers.ModelSerializer):
general_errors = serializer.CharField(source="self_description")
general_error = serializers.CharField(required=False, allow_null=True,
validators=[])
class Meta:
model = Elements
fields = ('general_error',......)
I would like a user to send a GET request to my Django REST API:
127.0.0.1:8000/model/?radius=5&longitude=50&latitude=55.1214
with his longitude/latitude and radius, passed in parameters, and get the queryset using GeoDjango.
For example, currently I have:
class ModelViewSet(viewsets.ModelViewSet):
queryset = Model.objects.all()
And what I ideally want is:
class ModelViewSet(viewsets.ModelViewSet):
radius = request.data['radius']
location = Point(request.data['longitude'],request.data['latitude']
# filter results by distance using geodjango
queryset = Model.objects.filer(location__distance_lte=(location, D(m=distance))).distance(location).order_by('distance')
Now a couple of immediate errors:
1) request is not defined - should I use api_view, i.e. the function based view for this?
2) DRF page says that request.data is for POST, PUT and PATCH methods only. How can send parameters with GET?
You can override get_queryset method for that purpose. As for query string parameters, you are right, request.data holds POST data, you can get query string params through request.query_params
def get_queryset(self):
longitude = self.request.query_params.get('longitude')
latitude= self.request.query_params.get('latitude')
radius = self.request.query_params.get('radius')
location = Point(longitude, latitude)
queryset = Model.objects.filter(location__distance_lte=(location, D(m=distance))).distance(location).order_by('distance')
return queryset
I had the same problem, to solve it you can get parameters from url with self.request.parser_context.get('kwargs') under the get_queryset method.
this actually worked for me .
using the self.request.query_params.get("lead_contact_id")
def get_queryset(self,*args,**kwargs):
# the lead id
lead_contact_id = self.request.query_params.get("lead_contact_id")
# this filter base on the lead id provided
feedback = Feedback.objects.filter(object_id=lead_contact_id)
return feedback
Hi I am implementing test cases for my models.
I am using Mongoengine0.9.0 + Django 1.8
My models.py
class Project(Document):
# commented waiting for org-group to get finalize
project_name = StringField()
org_group = ListField(ReferenceField(OrganizationGroup, required=False))
My Serializers.py
class ProjectSerializer(DocumentSerializer):
class Meta:
model = Project
depth = 1
test.py file
def setUp(self):
# Every test needs access to the request factory.
self.factory = RequestFactory()
self.user = User.objects.create_user(
username='jacob', email='jacob#jacob.com', password='top_secret')
def test_post_put_project(self):
"""
Ensure we can create new clients in mongo database.
"""
org_group = str((test_utility.create_organization_group(self)).id)
url = '/project-management/project/'
data = {
"project_name": "googer",
"org_group": [org_group],
}
##import pdb; pdb.set_trace()
factory = APIRequestFactory()
user = User.objects.get(username='jacob')
view = views.ProjectList.as_view()
# Make an authenticated request to the view...
request = factory.post(url, data=data,)
force_authenticate(request, user=user)
response = view(request)
self.assertEqual(response.status_code, 200)
When I am running test cases I am getting this error
(Only lists and tuples may be used in a list field: ['org_group'])
The complete Stack Trace is
ValidationError: Got a ValidationError when calling Project.objects.create().
This may be because request data satisfies serializer validations but not Mongoengine`s.
You may need to check consistency between Project and ProjectSerializer.
If that is not the case, please open a ticket regarding this issue on https://github.com/umutbozkurt/django-rest-framework-mongoengine/issues
Original exception was: ValidationError (Project:None) (Only lists and tuples may be used in a list field: ['org_group'])
Not getting why we cant pass object like this.
Same thing when I am posting as an request to same method It is working for me but test cases it is failing
The tests should be running using multipart/form-data, which means that they don't support lists or nested data.
You can override this with the format argument, which I'm guessing you probably want to set to json. Most likely your front-end is using JSON, or a parser which supports lists, which explains why you are not seeing this.
Full Disclosure: Cross posted to Tastypie Google Group
I have a situation where I have limited control over what is being sent to my api. Essentially there are two webservices that I need to be able to accept POST data from. Both use plain POST actions with urlencoded data (basic form submission essentially).
Thinking about it in "curl" terms it's like:
curl --data "id=1&foo=2" http://path/to/api
My problem is that I can't update records using POST. So I need to adjust the model resource (I believe) such that if an ID is specified, the POST acts as a PUT instead of a POST.
api.py
class urlencodeSerializer(Serializer):
formats = ['json', 'jsonp', 'xml', 'yaml', 'html', 'plist', 'urlencoded']
content_types = {
'json': 'application/json',
'jsonp': 'text/javascript',
'xml': 'application/xml',
'yaml': 'text/yaml',
'html': 'text/html',
'plist': 'application/x-plist',
'urlencoded': 'application/x-www-form-urlencoded',
}
# cheating
def to_urlencoded(self,content):
pass
# this comes from an old patch on github, it was never implemented
def from_urlencoded(self, data,options=None):
""" handles basic formencoded url posts """
qs = dict((k, v if len(v)>1 else v[0] )
for k, v in urlparse.parse_qs(data).iteritems())
return qs
class FooResource(ModelResource):
class Meta:
queryset = Foo.objects.all() # "id" = models.AutoField(primary_key=True)
resource_name = 'foo'
authorization = Authorization() # only temporary, I know.
serializer = urlencodeSerializer()
urls.py
foo_resource = FooResource
...
url(r'^api/',include(foo_resource.urls)),
)
In #tastypie on Freenode, Ghost[], suggested that I overwrite post_list() by creating a function in the model resource like so, however, I have not been successful in using this as yet.
def post_list(self, request, **kwargs):
if request.POST.get('id'):
return self.put_detail(request,**kwargs)
else:
return super(YourResource, self).post_list(request,**kwargs)
Unfortunately this method isn't working for me. I'm hoping the larger community could provide some guidance or a solution for this problem.
Note: I cannot overwrite the headers that come from the client (as per: http://django-tastypie.readthedocs.org/en/latest/resources.html#using-put-delete-patch-in-unsupported-places)
I had a similar problem on user creation where I wasn't able to check if the record already existed. I ended up creating a custom validation method which validated if the user didn't exist in which case post would work fine. If the user did exist I updated the record from the validation method. The api still returns a 400 response but the record is updated. It feels a bit hacky but...
from tastypie.validation import Validation
class MyValidation(Validation):
def is_valid(self, bundle, request=None):
errors = {}
#if this dict is empty validation passes.
my_foo = foo.objects.filter(id=1)
if not len(my_foo) == 0: #if object exists
foo[0].foo = 'bar' #so existing object updated
errors['status'] = 'object updated' #this will be returned in the api response
return errors
#so errors is empty if object does not exist and validation passes. Otherwise object
#updated and response notifies you of this
class FooResource(ModelResource):
class Meta:
queryset = Foo.objects.all() # "id" = models.AutoField(primary_key=True)
validation = MyValidation()
With Cathal's recommendation I was able to utilize a validation function to update the records I needed. While this does not return a valid code... it works.
from tastypie.validation import Validation
import string # wrapping in int() doesn't work
class Validator(Validation):
def __init__(self,**kwargs):
pass
def is_valid(self,bundle,request=None):
if string.atoi(bundle.data['id']) in Foo.objects.values_list('id',flat=True):
# ... update code here
else:
return {}
Make sure you specify the validation = Validator() in the ModelResource meta.