|
| 1 | +from django.db.models import Model |
| 2 | +from django.core.exceptions import ImproperlyConfigured |
| 3 | + |
| 4 | +from rest_framework import serializers |
| 5 | +from rest_framework.exceptions import ValidationError |
| 6 | +from rest_framework.fields import empty |
| 7 | + |
| 8 | + |
| 9 | +class FieldPolymorphicSerializer(serializers.Serializer): |
| 10 | + field_value_serializer_mapping = None |
| 11 | + resource_type_field_name = "type" |
| 12 | + model = None |
| 13 | + |
| 14 | + def __new__(cls, *args, **kwargs): |
| 15 | + if cls.field_value_serializer_mapping is None: |
| 16 | + raise ImproperlyConfigured( |
| 17 | + "`{cls}` is missing a " |
| 18 | + "`{cls}.field_value_serializer_mapping` attribute".format( |
| 19 | + cls=cls.__name__ |
| 20 | + ) |
| 21 | + ) |
| 22 | + if not isinstance(cls.resource_type_field_name, str): |
| 23 | + raise ImproperlyConfigured( |
| 24 | + "`{cls}.resource_type_field_name` must be a string".format( |
| 25 | + cls=cls.__name__ |
| 26 | + ) |
| 27 | + ) |
| 28 | + if not issubclass(cls.model, Model): |
| 29 | + raise ImproperlyConfigured( |
| 30 | + "`{cls}.model` must be a django Model".format(cls=cls.__name__) |
| 31 | + ) |
| 32 | + return super().__new__(cls, *args, **kwargs) |
| 33 | + |
| 34 | + def __init__(self, *args, **kwargs): |
| 35 | + super().__init__(*args, **kwargs) |
| 36 | + field_value_serializer_mapping = self.field_value_serializer_mapping |
| 37 | + self.field_value_serializer_mapping = {} |
| 38 | + for field_value, serializer in field_value_serializer_mapping.items(): |
| 39 | + if callable(serializer): |
| 40 | + serializer = serializer(*args, **kwargs) |
| 41 | + serializer.parent = self |
| 42 | + |
| 43 | + self.field_value_serializer_mapping[field_value] = serializer |
| 44 | + |
| 45 | + def to_representation(self, instance): |
| 46 | + serializer = self._get_serializer_for_instance(instance=instance) |
| 47 | + return serializer.to_representation(instance) |
| 48 | + |
| 49 | + def to_internal_value(self, data): |
| 50 | + if self.instance: |
| 51 | + serializer = self._get_serializer_for_instance(instance=self.instance) |
| 52 | + else: |
| 53 | + serializer = self._get_serializer_for_data(data=data) |
| 54 | + return serializer.to_internal_value(data=data) |
| 55 | + |
| 56 | + def create(self, validated_data): |
| 57 | + serializer = self._get_serializer_for_data(data=validated_data) |
| 58 | + return serializer.create(validated_data) |
| 59 | + |
| 60 | + def update(self, instance, validated_data): |
| 61 | + serializer = self._get_serializer_for_data(data=validated_data) |
| 62 | + return serializer.update(instance, validated_data) |
| 63 | + |
| 64 | + def is_valid(self, raise_exception=False): |
| 65 | + valid = super().is_valid(raise_exception) |
| 66 | + |
| 67 | + try: |
| 68 | + if self.instance: |
| 69 | + serializer = self._get_serializer_for_instance(instance=self.instance) |
| 70 | + else: |
| 71 | + serializer = self._get_serializer_for_data(data=self.initial_data) |
| 72 | + except ValidationError: |
| 73 | + child_valid = False |
| 74 | + else: |
| 75 | + child_valid = serializer.is_valid(raise_exception) |
| 76 | + self._errors.update(serializer.errors) |
| 77 | + |
| 78 | + return valid and child_valid |
| 79 | + |
| 80 | + def run_validation(self, data=empty): |
| 81 | + if self.instance: |
| 82 | + serializer = self._get_serializer_for_instance(instance=self.instance) |
| 83 | + else: |
| 84 | + serializer = self._get_serializer_for_data(data=data) |
| 85 | + return serializer.run_validation(data) |
| 86 | + |
| 87 | + def _get_serializer_for_type(self, type_value): |
| 88 | + try: |
| 89 | + return self.field_value_serializer_mapping[type_value] |
| 90 | + except KeyError: |
| 91 | + raise ValidationError( |
| 92 | + f"Value {type_value} has not serializer assigned for field '{self.resource_type_field_name}'" |
| 93 | + ) |
| 94 | + |
| 95 | + def _get_serializer_for_instance(self, instance): |
| 96 | + return self._get_serializer_for_type( |
| 97 | + type_value=getattr(instance, self.resource_type_field_name) |
| 98 | + ) |
| 99 | + |
| 100 | + def _get_serializer_for_data(self, data): |
| 101 | + try: |
| 102 | + return self._get_serializer_for_type( |
| 103 | + type_value=data[self.resource_type_field_name] |
| 104 | + ) |
| 105 | + except KeyError: |
| 106 | + raise ValidationError( |
| 107 | + f"{self.resource_type_field_name} is a required field." |
| 108 | + ) |
0 commit comments