如何在Django REST Framework中根据关联模型数据过滤主模型并返回匹配结果

Hey there! Let's work through how to filter your MainModel records based on the related ModelAdditionalData_1 and ModelAdditionalData_2 fields using those query parameters. Here's a step-by-step solution:

First, Fix a Tiny Model Typo #

I spotted a small mistake in your related models: the OneToOneField references Model, but your main model is named MainModel. Plus, there's a duplicate models. prefix on the DecimalField definitions. Correct those first to avoid errors:

class ModelAdditionalData_1(TimeStampedModel):
    model_id = models.OneToOneField(
        MainModel,  # Changed from "Model" to "MainModel"
        verbose_name=_('related model'), 
        on_delete=models.CASCADE,
        related_name='model_water_flow_data1', 
        related_query_name='model_water_flow_data1'
    )
    model_param_1 = models.DecimalField(_("model_param_1"), max_digits=8)  # Fixed duplicate "models."

class ModelAdditionalData_2(TimeStampedModel):
    model_id = models.OneToOneField(
        MainModel,  # Changed from "Model" to "MainModel"
        verbose_name=_('related model'), 
        on_delete=models.CASCADE,
        related_name='model_water_flow_data2', 
        related_query_name='model_water_flow_data2'
    )
    model_param_2 = models.DecimalField(_("model_param_2"), max_digits=8)  # Fixed duplicate "models."

Update Your View to Handle Filtering #

Instead of handling filtering directly in the list method, override the get_queryset method (this follows DRF best practices). We'll use Django's double-underscore lookup to filter across the one-to-one relationships:

from decimal import Decimal, InvalidOperation

DETAIL_FILTER_PARAMETERS = [
    openapi.Parameter(
        'model_param_1', openapi.IN_QUERY, type=openapi.TYPE_STRING, format=openapi.FORMAT_DECIMAL
    ),
    openapi.Parameter(
        'model_param_2', openapi.IN_QUERY, type=openapi.TYPE_STRING, format=openapi.FORMAT_DECIMAL
    )
]

@method_decorator(name='list', decorator=swagger_auto_schema(
    manual_parameters=DETAIL_FILTER_PARAMETERS))
class ModelsViewSet(ReadOnlyModelViewSet):
    serializer_class = ModelsSerializer
    queryset = MainModel.objects.all()

    def get_queryset(self):
        # Start with the base queryset
        queryset = super().get_queryset()
        
        # Extract query parameters from the request
        param1 = self.request.query_params.get('model_param_1')
        param2 = self.request.query_params.get('model_param_2')

        # Build dynamic filter dictionary
        filters = {}
        
        # Handle model_param_1: validate and add to filters
        if param1 is not None:
            try:
                # Convert string to Decimal to match the field type
                param1_decimal = Decimal(param1)
                filters['model_water_flow_data1__model_param_1'] = param1_decimal
            except InvalidOperation:
                # Optional: Return empty set or raise a 400 error for invalid input
                return MainModel.objects.none()
        
        # Handle model_param_2 similarly
        if param2 is not None:
            try:
                param2_decimal = Decimal(param2)
                filters['model_water_flow_data2__model_param_2'] = param2_decimal
            except InvalidOperation:
                return MainModel.objects.none()
        
        # Apply filters if any are set
        if filters:
            queryset = queryset.filter(**filters)
        
        return queryset

How This Works #

• The related_name values (model_water_flow_data1 and model_water_flow_data2) let us traverse from MainModel to its related data using the double-underscore syntax (model_water_flow_data1__model_param_1).
• We validate incoming string parameters to convert them to Decimal (matching your model field type) to avoid type mismatches.
• Filters are applied dynamically: if only one parameter is provided, it filters on just that field; if both are provided, it returns records that match both conditions.

Optional: Update Serializer to Include Related Data #

If you want the response to include the related ModelAdditionalData fields, update your serializer to nest them:

from rest_framework import serializers

class ModelAdditionalData1Serializer(serializers.ModelSerializer):
    class Meta:
        model = ModelAdditionalData_1
        fields = ['model_param_1']

class ModelAdditionalData2Serializer(serializers.ModelSerializer):
    class Meta:
        model = ModelAdditionalData_2
        fields = ['model_param_2']

class ModelsSerializer(serializers.ModelSerializer):
    model_water_flow_data1 = ModelAdditionalData1Serializer()
    model_water_flow_data2 = ModelAdditionalData2Serializer()

    class Meta:
        model = MainModel
        fields = ['id', 'model_name', 'model_price', 'model_water_flow_data1', 'model_water_flow_data2']

Test Your Filter #

Run your server and use the curl command you provided:

curl -X GET "http://localhost:8000/api/v1/models/?model_param_1=1&model_param_2=2" -H "accept: application/json"

This will return only MainModel records where the related ModelAdditionalData_1.model_param_1 equals 1 and ModelAdditionalData_2.model_param_2 equals 2.

内容的提问来源于stack exchange，提问作者MrOldSir