Created
March 31, 2020 08:36
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rest frame work 动态返回字段
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| import typing | |
| from collections import OrderedDict | |
| from django.db import models | |
| from django.db.models.fields import related_descriptors | |
| from rest_framework import serializers | |
| from rest_framework.fields import SkipField | |
| from rest_framework.relations import PKOnlyObject | |
| class DynamicFieldModelSerializer(serializers.ModelSerializer): | |
| include_parameters = 'include' | |
| def get_fields_for_serializer(self, parameter_name: typing.List[str] = None) -> typing.Union[typing.Set, None]: | |
| include_name = parameter_name or self.include_parameters | |
| if include_name in self.context: | |
| fields = set(self.context[include_name]) | |
| elif "request" in self.context and include_name in self.context["request"].query_params: | |
| fields = set(self.context['request'].query_params[include_name].split(',')) | |
| else: | |
| fields = None | |
| return fields | |
| def to_representation(self, instance): | |
| ret = OrderedDict() | |
| fields = self._readable_fields | |
| include_fields = self.get_fields_for_serializer() | |
| for field in fields: | |
| if include_fields and field.field_name not in include_fields: | |
| continue | |
| try: | |
| attribute = field.get_attribute(instance) | |
| except SkipField: | |
| continue | |
| check_for_none = attribute.pk if isinstance(attribute, PKOnlyObject) else attribute | |
| if check_for_none is None: | |
| ret[field.field_name] = None | |
| else: | |
| # pass child serializer fields | |
| ret[field.field_name] = field.to_representation(attribute) | |
| return ret | |
| class AutoOptimizationMixin: | |
| def get_queryset(self): | |
| serializer = self.get_serializer_class()(context=self.get_serializer_context()) | |
| include_fields = set() | |
| if isinstance(serializer, DynamicFieldModelSerializer): | |
| include_fields = serializer.get_fields_for_serializer() | |
| selected_related, prefetch_related = auto_optimization('', serializer, include_fields) | |
| queryset = super().get_queryset() | |
| if selected_related: | |
| queryset = queryset.select_related(*list(selected_related)) | |
| if prefetch_related: | |
| queryset = queryset.prefetch_related(*list(prefetch_related)) | |
| return queryset | |
| def auto_optimization(prefix: str, serializer: 'DynamicFieldModelSerializer', include_fields: typing.Iterable[str]) -> ( | |
| typing.Set, typing.Set): | |
| if not hasattr(serializer, 'Meta') or not hasattr(serializer.Meta, 'model'): | |
| return | |
| model_class = serializer.Meta.model | |
| select_related = set() | |
| prefetch_related = set() | |
| for field_name, field in serializer.fields.items(): | |
| if field_name not in include_fields: | |
| continue | |
| if isinstance(field, serializers.Serializer): | |
| if '.' not in field.source and hasattr(model_class, field.source): | |
| if isinstance(getattr(model_class, field.source), related_descriptors.ManyToManyDescriptor): | |
| prefetch_related.add(prefix + field.source) | |
| else: | |
| select_related.add(prefix + field.source) | |
| elif '.' in field.source: | |
| field_name = field.source.split('.', 1)[0] | |
| # 检查是否可以外键查询 | |
| if isinstance(getattr(model_class, field_name, None), models.ForeignKey): | |
| select_related.add(prefix + field_name) | |
| return select_related, prefetch_related |
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