AssertionError: The `.create()` method does not support writable nested fields by default. about drf-writable-nested

[ruscoder]

Hello @beautifulDrifter!
Thank you for finding the bug with different field names specified via source attribute.

You have to fix the following errors:

• Update drf-writable-nested to 0.3.1 (just uploaded to PyPI)
• Add source='category' to the categoryArray declaration: categoryArray = categoryArray(many=True, source='category')
• Add related_name='details' to response_log = models.ForeignKey(response_log) (The drf-writable-nested current doesn't support implicit related_names, alas)
• Add source='details' to the getCategoriesResponse declaration: getCategoriesResponse = getCategoriesResponse(source='details')
• Pass list of getCategoriesResponse instead of one (because you have reverse FK field)

response = {'ack': 'Success',
 'getCategoriesResponse': [{'categoryArray': [{'categoryBriefName': 'Collectibles',
    'categoryId': 1,
    'categoryLevel': 1,
    'categoryName': 'Collectibles',
    'leafCategory': 'false',
    'traitCount': 1},
   {'categoryBriefName': 'Everything Else',
    'categoryId': 99,
    'categoryLevel': 1,
    'categoryName': 'Everything Else',
    'leafCategory': 'false',
    'traitCount': 5}]}],
 'timestamp': '2017-10-12T12:00:40.000Z',
 'version': '1.0'}

[ruscoder]

I've created a separated issue to improve error messages. It's very easy to make a mistake like this.

[beautifulDrifter]

Thanks for the quick turn around! I was literally about to send you where I thought I saw the hiccup.

[ruscoder]

@beautifulDrifter
Also you can use
getCategoriesResponse = getCategoriesResponse(source='response_log_detail', many=True) without changing the default related_name for the response_log field

[beautifulDrifter]

Hey @ruscoder , now I am getting the following error.

/usr/local/lib/python3.4/dist-packages/drf_writable_nested/mixins.py in save(self, **kwargs)
171 self.save_kwargs = defaultdict(dict, kwargs)
172
--> 173 return super(BaseNestedModelSerializer, self).save(**kwargs)
174
175 def get_save_kwargs(self, field_name):

TypeError: super(type, obj): obj must be an instance or subtype of type

I actually popped out the inner serializer to make sure that wasn't what was causing the issue.

class responseSerializer(WritableNestedModelSerializer):
    # Fields #
    #getCategoriesResponse = getCategoriesResponse()
    ack = s.CharField(source='status')
    timestamp = s.DateTimeField()
    
    
    class Meta:
        model = response_log
        fields = (
        'pk',
        'ack',
        #'getCategoriesResponse',
        'timestamp',
        )

[ruscoder]

@beautifulDrifter I can't reproduce your problem
There is a working example:

class category(models.Model):
    name = models.CharField(max_length=255, help_text="", blank=True)
    short_name = models.CharField(max_length=255, help_text="", blank=True)
    external_id = models.CharField(max_length=255, help_text="", blank=True)


    def __str__(self):
        return self.name


class response_log(models.Model):
    timestamp = models.DateTimeField()
    status = models.CharField(max_length=25)


class response_log_detail(models.Model):
    response_log = models.ForeignKey(response_log)
    category = models.ManyToManyField(category)

from rest_framework import serializers as s
from drf_writable_nested import WritableNestedModelSerializer

class categoryArray(s.ModelSerializer):
    # Fields #
    categoryId = s.IntegerField(source='external_id')
    categoryName = s.CharField(source='name')
    categoryBriefName = s.CharField(source='short_name')

    class Meta:
        model = category
        fields = (
                'categoryId',
                'categoryName',
                'categoryBriefName',
                )

class getCategoriesResponse(WritableNestedModelSerializer):
    # Fields #
    categoryArray = categoryArray(many=True, source='category')
    # errorMessage = bonanzaErrorMessage()
    # warnings = bonanzaWarnings()
    class Meta:
        model = response_log_detail
        fields = (
                'pk',
                'categoryArray',
                # 'errorMessage',
                # 'warnings',
                )
class responseSerializer(WritableNestedModelSerializer):
    # Fields #
    getCategoriesResponse = getCategoriesResponse(source='response_log_detail', many=True)
    ack = s.CharField(source='status')
    class Meta:
        model = response_log
        fields = (
        'pk',
        'ack',
        'getCategoriesResponse',
        'timestamp',
        )


response = {'ack': 'Success',
            'getCategoriesResponse': [{
                'categoryArray': [{'categoryBriefName': 'Collectibles',
                                   'categoryId': 1,
                                   'categoryLevel': 1,
                                   'categoryName': 'Collectibles',
                                   'leafCategory': 'false',
                                   'traitCount': 1},
                                  {
                                      'categoryBriefName':
                                          'Everything Else',
                                      'categoryId': 99,
                                      'categoryLevel': 1,
                                      'categoryName': 'Everything Else',
                                      'leafCategory': 'false',
                                      'traitCount': 5}]}],
            'timestamp': '2017-10-12T12:00:40.000Z',
            'version': '1.0'}

serializer = serializers.responseSerializer(data=response)
serializer.is_valid(raise_exception=True)
response_log = serializer.save()

Note: make sure that you use drf-writable-nested 0.3.1

[beautifulDrifter]

@ruscoder unfortunately I cannot reformat the json, so I am making my models fit to it for now. I imagine that will be a typical use case as this will enable people to deserialize responses from external web services. Now I am getting the error but on the second (inner) serializer.

AssertionError: The .create() method does not support writable nested fields by default.
Write an explicit .create() method for serializer modex_connect.serializers.getCategoriesResponse, or set read_only=True on nested serializer fields.

I have tried both setting a OneToOne on response_log_detail and a ForeignKey on response_log and neither have worked. Eventually I will flatten these two models once I get the deserialization working. I also removed the categoryArray from the getCategoriesResponse to validate that the responseSerializer worked properly and everything worked correctly. The fix you added only seems to be taking effect on the top level serializer OR it has something to do with the many to many. Let me know and thanks for all of your help!

Models:

class category(models.Model):
    name = models.CharField(max_length=255, help_text="", blank=True)
    short_name = models.CharField(max_length=255, help_text="", blank=True)
    external_id = models.CharField(max_length=255, help_text="", blank=True)
    def __str__(self):
        return self.name

class response_log_detail(models.Model):
    category_id = models.ManyToManyField(category)
    #response_log = models.OneToOneField(response_log, null = True, blank = True)
     
class response_log(models.Model):
    timestamp = models.DateTimeField()
    status = models.CharField(max_length = 25, null=True, blank=True)
    category_id = models.ManyToManyField(category)
    response_log_detail = models.ForeignKey(response_log_detail, null=True, blank=True)

Serializers:

class categoryArray(s.ModelSerializer):
   
    # Fields #
    categoryId = s.IntegerField(source='external_id')
    categoryName = s.CharField(source='name')
    categoryBriefName = s.CharField(source='short_name')

    class Meta:
        model = category
        fields = (
                'categoryId',
                'categoryName',
                'categoryBriefName',
                )

class getCategoriesResponse(WritableNestedModelSerializer):
    # Fields #
    categoryArray = categoryArray(many=True,source='category')
    # errorMessage = bonanzaErrorMessage()
    # warnings = bonanzaWarnings()
    class Meta:
        model = response_log_detail
        fields = (
                'pk',
                'categoryArray',
                # 'errorMessage',
                # 'warnings',
                )

class responseSerializer(WritableNestedModelSerializer):
    # Fields #
    getCategoriesResponse = getCategoriesResponse(source='response_log_detail')
    ack = s.CharField(source='status')
    timestamp = s.DateTimeField()
    #getCategoriesResponse = getCategoriesResponse()
    
    
    class Meta:
        model = response_log
        fields = (
        'pk',
        'getCategoriesResponse',
        'ack',
        'timestamp',
        #'categoryArray',
        )

[ruscoder]

@beautifulDrifter
You have a mistake:

class getCategoriesResponse(WritableNestedModelSerializer):
    # Fields #
    categoryArray = categoryArray(many=True,source='category')
    # errorMessage = bonanzaErrorMessage()
    # warnings = bonanzaWarnings()
    class Meta:
        model = response_log_detail
        fields = (
                'pk',
                'categoryArray',
                # 'errorMessage',
                # 'warnings',
                )

in the line categoryArray = categoryArray(many=True,source='category').
It should be: categoryArray = categoryArray(many=True,source='category_id') because you've renamed category to category_id.

[beautifulDrifter]

Yes. I just realized that about an hour ago. Also there was an issue with shell and auto reload not working correctly. Known bug I apperently didn't know about. Thanks for your help. This is an awesome tool. Im almost done with a mixin that will populate pk based on an identifier other than the pk for updating records. Will kick it over on the other thread when I'm finished. Will be very raw but could be a good starting point for you on adding this feature.

…

On Tue, Oct 17, 2017 at 2:04 AM Vadim Laletin ***@***.***> wrote: @beautifulDrifter <https://github.com/beautifuldrifter> You have a mistake: class getCategoriesResponse(WritableNestedModelSerializer): # Fields # categoryArray = categoryArray(many=True,source='category') # errorMessage = bonanzaErrorMessage() # warnings = bonanzaWarnings() class Meta: model = response_log_detail fields = ( 'pk', 'categoryArray', # 'errorMessage', # 'warnings', ) in line categoryArray = categoryArray(many=True,source='category'). It should be: categoryArray = categoryArray(many=True,source='category_id') because you've renamed category to category_id. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#22 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AfOm5z5ukDxQwI57IUSTa-qCAHgLZ_T3ks5stENjgaJpZM4P3en6> .