How to get GeoJSON response in Django REST framework gis

[Shoaib Ijaz]

I am trying to get GeoJSON response using django rest framework but facing issue

argument of type 'NoneType' is not iterable

This is my code

class NewPark(models.Model):
    name = models.CharField(max_length=256)
    geometry = models.GeometryField(srid=3857, null=True, blank=True)
    objects = models.GeoManager()

    class Meta:
        db_table = u'new_park'

    def __unicode__(self):
        return '%s' % self.name


class NewParkSerializer(GeoFeatureModelSerializer):
    class Meta:
        model = NewPark
        geo_field = "geometry"
        fields = ('id', 'name', 'geometry')

class NewParkViewSet(viewsets.ModelViewSet):

    def get_queryset(self):

        queryset = NewPark.objects.all()
        return queryset

When i change serialize type to 'erializers.GeoModelSerializer' then it is working, but i want GEOJSON response

I have searched about GeoFeatureModelSerializer but cannot find any example geo_field = "geometry". All example are about geo_field = "point"

Please help me to figure out this issue?

[Douglas Meehan]

Take a look at your "fields" tuple. You should not be specifying 'geometry' here, as it is already taken care of as the "geo_field"

Also, if you want to specify 'id' as part of fields, you need to set "id_field" to False:

class NewParkSerializer(GeoFeatureModelSerializer):
    class Meta:
        model = NewPark
        geo_field = "geometry"

        id_field = False
        fields = ('id', 'name')

https://github.com/djangonauts/django-rest-framework-gis/blob/master/README.rst

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[Nemesis]

I really don't understand.

The code you supplied seems correct so either you are doing something wrong or there's a problem with viewsets.

Have you tried with a normal view to see if there's any difference?

Federico

--

[Nemesis]

Oh.. ok, Douglas seems right.

[Shoaib Ijaz]

Yes, also tried this way but same error

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[Douglas Meehan]

Then the error must be somewhere else in your code.

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[Douglas Meehan]

Can you post the stack trace? Perhaps is because you are allowing the geometry field to be blank and null?

geometry = models.GeometryField(srid=3857, null=True, blank=True)

[Shoaib Ijaz]

when i changed the GeoFeatureModelSerializer to serializers.GeoModelSerializer then it is working. So i think there is issue with geometry type field. Am i right?

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[Douglas Meehan]

Can you post the full stack trace?

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[Shoaib Ijaz]

Environment:


Request Method: GET
Request URL: http://127.0.0.1:8001/PoiLorryparkViewSet/

Django Version: 1.6
Python Version: 2.7.1
Installed Applications:
('django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'django.contrib.admin',
 'django.contrib.gis',
 'data_api',
 'rest_framework')
Installed Middleware:
('django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.common.CommonMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware')


Traceback:
File "C:\Python27\lib\site-packages\django\core\handlers\base.py" in get_response
  139.                 response = response.render()
File "C:\Python27\lib\site-packages\django\template\response.py" in render
  105.             self.content = self.rendered_content
File "C:\Python27\lib\site-packages\rest_framework\response.py" in rendered_content
  59.         ret = renderer.render(self.data, media_type, context)
File "C:\Python27\lib\site-packages\rest_framework\renderers.py" in render
  592.         context = self.get_context(data, accepted_media_type, renderer_context)
File "C:\Python27\lib\site-packages\rest_framework\renderers.py" in get_context
  569.             'post_form': self.get_rendered_html_form(view, 'POST', request),
File "C:\Python27\lib\site-packages\rest_framework\renderers.py" in get_rendered_html_form
  448.             serializer.is_valid()
File "C:\Python27\lib\site-packages\rest_framework\serializers.py" in is_valid
  551.         return not self.errors
File "C:\Python27\lib\site-packages\rest_framework\serializers.py" in errors
  543.                 ret = self.from_native(data, files)
File "C:\Python27\lib\site-packages\rest_framework_gis\serializers.py" in from_native
  115.         if 'features' in data:

Exception Type: TypeError at /PoiLorryparkViewSet/
Exception Value: argument of type 'NoneType' is not iterable

[Shoaib Ijaz]

Now i changed this field, but same issue

geometry = models.GeometryField()

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[Douglas Meehan]

Are you specifying a serializer class in your viewset?

http://www.django-rest-framework.org/api-guide/viewsets#modelviewset

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[Shoaib Ijaz]

Sorry i forgot to write this line view. yes i am doing thats why it is working for serializers.GeoModelSerializer. this is my complete view

class NewParkViewSet(viewsets.ModelViewSet):

    serializer_class = NewParkSerializer

[Douglas Meehan]

Why are you overriding get_queryset?

class AccountViewSet(viewsets.ModelViewSet):
    """
    A simple ViewSet for viewing and editing accounts.
    """
    queryset = Account.objects.all()
    serializer_class = AccountSerializer
    permission_classes = [IsAccountAdminOrReadOnly]

[Shoaib Ijaz]

i have also tried in this way but same issue and set permission for allowany but same issue

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[Douglas Meehan]

Sorry, I'm not sure what is going wrong with your code. All I can tell is that there is no data being returned by your view:

if 'features' in data:

Exception Type: TypeError at /PoiLorryparkViewSet/

Exception Value: argument of type 'NoneType' is not iterable

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[Douglas Meehan]

Is it possible to change your GeometryField to something like a PointField or other subclass and see if that works?

[Shoaib Ijaz]

It cannot possible because i have more than hundreds tables , all tables contains geometry fields and thousand of record. 

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[Douglas Meehan]

Ok, just wanted to see if that is the issue, although I don't think it is as we have code that runs successfully using a GeometryField, in fact this is what is used in the tests:

https://github.com/djangonauts/django-rest-framework-gis/blob/master/tests/django_restframework_gis_tests/models.py

In fact, you might want to take a look at the test implementations and see what might be going wrong.

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[Douglas Meehan]

You might want to try Frederico's advice:

"Have you tried with a normal view to see if there's any difference?"

[Shoaib Ijaz]

Now i have also tried with new table and point field type but same error. i think now i have to change view type

[Nemesis]

Try with a normal view and let us know how it goes.

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[Shoaib Ijaz]

Sorry, i have question about normal view. how can i use GeoFeatureModelSerializer in normal view. Can you provide me simple example. Thank you

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[Douglas Meehan]

Take a look at the test implementation for an example. 

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[Douglas Meehan]

Normal view meaning a DRF view, not a Viewset 

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[Shoaib Ijaz]

Sorry, i cannot understand your reply, my question is how can i serialize (GeoFeatureModelSerializer) model in DRF view.  mean can i use serializer_class DRF view. i want GeoJson response is there any function available that convert queryset to GeoJSON?

[Douglas Meehan]

Still use GeoFeatureModelSerializer, but try it with a View rather than a ViewSet:

http://www.django-rest-framework.org/api-guide/views

http://www.django-rest-framework.org/api-guide/generic-views

Example:

https://github.com/djangonauts/django-rest-framework-gis/blob/master/tests/django_restframework_gis_tests/views.py

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[Shoaib Ijaz]

Now used this view but still same issue

class NewParkList(generics.ListCreateAPIView):

    serializer_class = NewParkSerializer   

    queryset = NewPark.objects.all()

I am using these configuration in setting file, please check anything missing here

REST_FRAMEWORK = {

    'DEFAULT_MODEL_SERIALIZER_CLASS':

        'rest_framework.serializers.HyperlinkedModelSerializer',

    'DEFAULT_PERMISSION_CLASSES': (

        'rest_framework.permissions.AllowAny',

    ),

    'PAGINATE_BY': 10,

} 

[Douglas Meehan]

Can you post your full models.py, views.py and urls.py also? 

[Douglas Meehan]

Check out this Stack Overflow question and answer: 

http://stackoverflow.com/questions/21308653/django-rest-framework-gis-trying-to-get-a-geojson-output

[Shoaib Ijaz]

Yes sure, now i have deleted other models now working with just one model

 

 model.py

from django.contrib.gis.db import models

from django.contrib.auth.models import User

class PoiLorrypark(models.Model):

    name = models.CharField(max_length=256)

    postcode = models.CharField(max_length=8, blank=True)

    phone = models.CharField(max_length=256, blank=True)

    email = models.CharField(max_length=256, blank=True)

    web = models.TextField(blank=True)

    geometry = models.GeometryField()

    objects = models.GeoManager()

    class Meta:

        db_table = u'lorrypark'

    def __unicode__(self):

        return '%s' % self.name

  serializers.py

from django.contrib.auth.models import User, Group

from data_api.models import *

from rest_framework import serializers

from rest_framework_gis import  serializers as gis_serializer

class PoiLorryparkSerializer(serializers.GeoModelSerializer):

    class Meta:

        model = PoiLorrypark

        fields = ('id', 'name', 'postcode' , 'geometry')

class PoiLorryparkFeatureSerializer(gis_serializer.GeoFeatureModelSerializer):

    class Meta:

        model = PoiLorrypark

        geo_field = "geometry"

        id_field = False

        fields = ('id', 'name', 'postcode')

 views.py

from data_api.models import *

from data_api.serializers import *

from rest_framework import generics

# tried both views for same model

class PoiLorryparkViewSet(viewsets.ModelViewSet):

    

    queryset = PoiLorrypark.objects.all()

    serializer_class = PoiLorryparkFeatureSerializer

    #serializer_class = PoiLorryparkSerializer  # this serializer is working 

class SnippetList(generics.ListCreateAPIView):

    queryset = PoiLorrypark.objects.all()

    serializer_class = PoiLorryparkFeatureSerializer

    #serializer_class = PoiLorryparkSerializer  # this serializer is working 

urls.py

from django.conf.urls import patterns, include, url

from rest_framework import routers

from data_api import views

from django.contrib import admin

admin.autodiscover()

urlpatterns = patterns('',

    url(r'^admin/', include(admin.site.urls)),

)

router = routers.DefaultRouter()

router.register(r'PoiLorryparkViewSet', views.PoiLorryparkViewSet, 'PoiLorryparkViewSet')

urlpatterns += patterns('',

    url(r'^', include(router.urls)),

    url(r'^SnippetList/$', views.SnippetList.as_view(), name='SnippetList'),

    url(r'^api-auth/', include('rest_framework.urls', namespace='rest_framework'))

)

 

[Shoaib Ijaz]

I am using django built in webserver and IDE is JetBrains PyCharm

 

 sudo stop uwsgi...

 sudo start uwsgi...  

[Shoaib Ijaz]

SETTINGS FILE

Django settings for DataExchanger project.

For more information on this file, see

https://docs.djangoproject.com/en/1.6/topics/settings/

For the full list of settings and their values, see

https://docs.djangoproject.com/en/1.6/ref/settings/

"""

# Build paths inside the project like this: os.path.join(BASE_DIR, ...)

import os

BASE_DIR = os.path.dirname(os.path.dirname(__file__))

# Quick-start development settings - unsuitable for production

# See https://docs.djangoproject.com/en/1.6/howto/deployment/checklist/

# SECURITY WARNING: keep the secret key used in production secret!

SECRET_KEY = 'q3%6lo2q!j$7rmc_9isko2pf&wyhe99ljbcdvzvx(3=bk61+^c'

# SECURITY WARNING: don't run with debug turned on in production!

DEBUG = True

TEMPLATE_DEBUG = True

ALLOWED_HOSTS = []

# Application definition

INSTALLED_APPS = (

    'django.contrib.admin',

    'django.contrib.auth',

    'django.contrib.contenttypes',

    'django.contrib.sessions',

    'django.contrib.messages',

    'django.contrib.staticfiles',

    'django.contrib.admin',

    'django.contrib.gis',

    'data_api',

    'rest_framework'

)

REST_FRAMEWORK = {

    'DEFAULT_MODEL_SERIALIZER_CLASS':

        'rest_framework.serializers.HyperlinkedModelSerializer',

    'DEFAULT_PERMISSION_CLASSES': (

        'rest_framework.permissions.AllowAny',

    ),

    'PAGINATE_BY': 10,

}

MIDDLEWARE_CLASSES = (

    'django.contrib.sessions.middleware.SessionMiddleware',

    'django.middleware.common.CommonMiddleware',

    'django.middleware.csrf.CsrfViewMiddleware',

    'django.contrib.auth.middleware.AuthenticationMiddleware',

    'django.contrib.messages.middleware.MessageMiddleware',

    'django.middleware.clickjacking.XFrameOptionsMiddleware',

)

ROOT_URLCONF = 'DataExchanger.urls'

WSGI_APPLICATION = 'DataExchanger.wsgi.application'

# Database

# https://docs.djangoproject.com/en/1.6/ref/settings/#databases

DATABASES = {

  'default' : {

        'ENGINE': 'django.contrib.gis.db.backends.postgis',

        'NAME': 'DATA_db',

        'USER': 'postgres',

        'PASSWORD': '****',

        'HOST': 'localhost',

        'PORT': '5432',

    }

}

# Internationalization

# https://docs.djangoproject.com/en/1.6/topics/i18n/

LANGUAGE_CODE = 'en-us'

TIME_ZONE = 'UTC'

USE_I18N = True

USE_L10N = True

USE_TZ = True

# Static files (CSS, JavaScript, Images)

# https://docs.djangoproject.com/en/1.6/howto/static-files/

STATIC_URL = '/static/'

[Douglas Meehan]

Don't think this would cause the error, but you don't have rest_framework_gis in your installed apps...

[Douglas Meehan]

from rest_framework import serializers

from rest_framework_gis import  serializers as gis_serializer

class PoiLorryparkSerializer(serializers.GeoModelSerializer):

    ...

class PoiLorryparkFeatureSerializer(gis_serializer.GeoFeatureModelSerializer):

   ...

Also, don't know if this is an error in your code or a copy/paste error, but check your module namespaces for the Geo serializers.

[Shoaib Ijaz]

I don't think because i am using some rest_framework_gis function that working perfectly, but now i added rest_framework_gis in installed aps , same issue

[Shoaib Ijaz]

I have also check rest_framework_gis app

this is my console messages

djangorestframework-gis

C:\Users\OneClout\Downloads\Programs>"C:\Python27\scripts\pip.exe" install djangorestframework-gis

Requirement already satisfied (use --upgrade to upgrade): djangorestframework-gis in c:\python27\lib\site-packages

Requirement already satisfied (use --upgrade to upgrade): djangorestframework>=2.2.2 in c:\python27\lib\site-packages (from djangorestframework-gis)

Cleaning up...

[Nemesis]

Hey Shoaib,

the best thing to do is to create a failing test case.

If you are able to replicate the problem in the test case we can see if it's a bug and fix it, or otherwise point you to the right direction to fix.

Federico

[Shoaib Ijaz]

Hello,

I got answer on my question on stackoverflow.

Now i am using this format for GEOJSON response /api/newpark?format=json




Now My question is, how can i make it browsable api. is there any solution exist?

[Douglas Meehan]

What version of rest_framework_gis are you using?

[Shoaib Ijaz]

 djangorestframework    2.3.13

 djangorestframework-gis       0.2

 simplejson     3.3.1

I have traced this issue in following file, but i cannot find why data is None in this function

rest_framework_gis ---> serializers.py --->

class GeoFeatureModelSerializer(GeoModelSerializer):

    """

    A subclass of GeoModelSerializer 

    that outputs geojson-ready data as

    features and feature collections

    """

    _options_class = GeoFeatureModelSerializerOptions

    def __init__(self, *args, **kwargs):

        super(GeoFeatureModelSerializer, self).__init__(*args, **kwargs)

        if self.opts.geo_field is None:

            raise ImproperlyConfigured("You must define a 'geo_field'.")

        else:

            # TODO: make sure the geo_field is a GeoDjango geometry field

            # make sure geo_field is included in fields

            if self.opts.exclude:

                if self.opts.geo_field in self.opts.exclude:

                    raise ImproperlyConfigured("You cannot exclude your 'geo_field'.")

            if self.opts.fields:

                if self.opts.geo_field not in self.opts.fields:

                    self.opts.fields = self.opts.fields + (self.opts.geo_field, )

                    self.fields = self.get_fields()        

    def to_native(self, obj):

        """

        Serialize objects -> primitives.

        """

        ret = self._dict_class()

        ret.fields = {}

        if self.opts.id_field is not False:

            ret["id"] = ""

        ret["type"] = "Feature"

        ret["geometry"] = {}

        ret["properties"] = self._dict_class()

        

        for field_name, field in self.fields.items():

            field.initialize(parent=self, field_name=field_name)

            key = self.get_field_key(field_name)

            value = field.field_to_native(obj, field_name)

            

            if self.opts.id_field is not False and field_name == self.opts.id_field:

                ret["id"] = value

            elif field_name == self.opts.geo_field:

                ret["geometry"] = value

            else:

                ret["properties"][key] = value

            

            ret.fields[key] = field

        return ret

 

    def _format_data(self):

        """

        Add GeoJSON compatible formatting to a serialized queryset list

        """

        _data = super(GeoFeatureModelSerializer, self).data

        if isinstance(_data, list):

            self._formatted_data = {}

            self._formatted_data["type"] = "FeatureCollection"

            self._formatted_data["features"] = _data

        else:

            self._formatted_data = _data

   

        return self._formatted_data

    @property

    def data(self):

        """

        Returns the serialized data on the serializer.

        """

        return self._format_data()

    def from_native_issue(self, data, files):

        """

        Override the parent method to first remove the GeoJSON formatting

        """

       Here data is None that's why causing issue

        if 'features' in data:

            _unformatted_data = []

            features = data['features']

            for feature in features:

                _dict = feature["properties"]

                geom = { self.opts.geo_field: feature["geometry"] }

                _dict.update(geom)

                _unformatted_data.append(_dict)

        elif 'properties' in data:

            _dict = data["properties"]

            geom = { self.opts.geo_field: data["geometry"] }

            _dict.update(geom)

            _unformatted_data = _dict

        else:

            _unformatted_data = data

        data = _unformatted_data

        instance = super(GeoFeatureModelSerializer, self).from_native(data, files)

        if not self._errors:

            return self.full_clean(instance)

So i remove all data inside this function, now working fine without change URL

    def from_native(self, data, files):

        pass

[Carl McMillan]

i am having same problem and are using ViewSets,

I  had similar solution that seems to work, 

But instead of removing everything from from_native function, just adding in a check for None

e.g.

    def from_native(self, data, files):

        """

        Override the parent method to first remove the GeoJSON formatting

        """

        if data is not None:

[Shoaib Ijaz]

is this any type of bug or anything missing on my side?

[Nemesis]

It might be a bug caused by a recent change in DRF that we need to handle.

A pull request with a failing test case would be very helpful.

On 03/25/2014 09:06 AM, Shoaib Ijaz wrote:

is this any type of bug or anything missing on my side?

[Nemesis]

It should be fixed in the latest dev version.