解决Django Rest Framework TypeError：无法用字典设置GeoPoint SpatialProxy

环境版本 #

• Django==3.2.16
• djangorestframework==3.12.0
• djangorestframework-gis==1.0

代码实现 #

Model定义 #

from django.contrib.gis.db import models
from django.utils.translation import gettext_lazy as _
class GeoPoint(models.Model):

    POINT_TYPE_CHOICES = (
       ("limite_cusaf","Límite CUSAF"),
       ("limite_cusaf_di","Límite CUSAF y DI"),
       ("limite_2_di","Límite 2 DI"),
       ("limite_3_di_mas","Límite 3 DI o más"),
       ("otros","Otros"),
    )

    geom = models.PointField(verbose_name=_("Localización"), srid=4326)
    id_cusaf = models.CharField(_("ID CUSAF"), max_length=50)
    code = models.CharField(_("Código Punto"), max_length=50)
    point_type = models.CharField(_("Tipo de Punto"), max_length=50, choices=POINT_TYPE_CHOICES)
    observations = models.TextField(_("Observaciones"), null=True, blank=True)
    
    def __str__(self):
        return self.cod_punto  # 注意：字段名应为code，此处存在笔误

    class Meta:
        db_table = 'aggregate_geopunto'
        managed = True
        verbose_name = 'Punto'
        verbose_name_plural = 'Puntos'

Serializer定义 #

from rest_framework_gis.serializers import GeoFeatureModelSerializer

class GeoPointSerializer(GeoFeatureModelSerializer):

    class Meta:
        model = GeoPoint
        geo_field = "geom"
        fields = ('id','geom','id_cusaf','code',
        'point_type','observations',)
        read_only_fields = ['id',]

View定义 #

class GeoPointAPICreate(generics.CreateAPIView):
    authentication_classes = []
    permission_classes = ()
    queryset = GeoPoint.objects.all()
    serializer_class = GeoPointSerializer

Postman请求内容 #

{
    "type": "Feature",
    "geometry": {
        "type": "Point",
        "coordinates": [
            -69.929352,
            18.547504
        ]
    },
    "properties": {
        "id_cusaf": "x001",
        "code": "1",
        "point_type": "limite_cusaf",
        "observations": "observationssdsd"
    }
}

错误栈 #

Traceback (most recent call last):
  File "/home/ernesto/Programming/django/virtualenvs/fichacusaf/lib/python3.10/site-packages/rest_framework/serializers.py", line 939, in create
    instance = ModelClass._default_manager.create(**validated_data)
  File "/home/ernesto/Programming/django/virtualenvs/fichacusaf/lib/python3.10/site-packages/django/db/models/manager.py", line 85, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/home/ernesto/Programming/django/virtualenvs/fichacusaf/lib/python3.10/site-packages/django/db/models/query.py", line 451, in create
    obj = self.model(**kwargs)
  File "/home/ernesto/Programming/django/virtualenvs/fichacusaf/lib/python3.10/site-packages/django/db/models/base.py", line 488, in __init__
    _setattr(self, field.attname, val)
  File "/home/ernesto/Programming/django/virtualenvs/fichacusaf/lib/python3.10/site-packages/django/contrib/gis/db/models/proxy.py", line 74, in __set__
    raise TypeError('Cannot set %s SpatialProxy (%s) with value of type: %s' % (
TypeError: Cannot set GeoPoint SpatialProxy (POINT) with value of type: <class 'dict'>

原因分析 #

错误核心是：序列化后的validated_data中，geom字段仍为字典格式，而Django的PointField需要接收GEOSGeometry对象，无法直接解析字典，因此抛出类型错误。结合使用的版本，djangorestframework-gis==1.0在处理GeoFeatureModelSerializer的POST请求时，可能未正确将GeoJSON格式的geometry转换为GEOSGeometry对象。

修复步骤 #

1. 配置正确的请求头 #

在Postman中，将请求的Content-Type设置为application/geo+json，这是GeoJSON数据的标准MIME类型，确保Serializer能正确识别并解析请求体。

2. 重写Serializer的create方法，手动转换geometry字段 #

如果步骤1无法解决问题，在Serializer中手动将GeoJSON字典转换为GEOSGeometry对象：

from django.contrib.gis.geos import GEOSGeometry
from rest_framework_gis.serializers import GeoFeatureModelSerializer

class GeoPointSerializer(GeoFeatureModelSerializer):
    class Meta:
        model = GeoPoint
        geo_field = "geom"
        fields = ('id','geom','id_cusaf','code','point_type','observations',)
        read_only_fields = ['id',]

    def create(self, validated_data):
        # 取出geom的字典数据
        geom_dict = validated_data.pop('geom')
        # 将GeoJSON字典转换为GEOSGeometry对象
        geom = GEOSGeometry(f"{geom_dict['type']}({geom_dict['coordinates'][0]} {geom_dict['coordinates'][1]})")
        validated_data['geom'] = geom
        # 调用父类方法创建实例
        return super().create(validated_data)

3. 修复Model中的笔误 #

Model的__str__方法中引用了不存在的cod_punto字段，应改为实际存在的code字段，避免后续出现其他错误：

def __str__(self):
    return self.code

内容的提问来源于stack exchange，提问作者Ernesto Ruiz