如何使用django-rest-framework-(gis)压平外键对象 [英] How can I flatten a foreignkey object with django-rest-framework-(gis)

问题描述

我一直在寻找解决方案，该解决方案是最新的并且针对我的问题，但是还没有找到解决方案或清晰的文档来证明我真正需要做的事情，以使关系扁平化以符合geojson规范

I have searched long and far for a solution that is up to date and specific to my problem but have yet not found a solution or a clear documentation on what I really need to do in order to flatten a relationship to become geojson compliant.

这个问题与我的几乎相同，但是解决方案或答案 无法解决问题，仍然会产生无效的GeoJSON.

This question is almost identical to mine, however the solutions or answers does not solve the problem and still produces invalid GeoJSON.

• django-rest-framework-gis相关字段

• 从另一个模型中将序列化器geo_field设置为PointField- Django
• Django REST Framework:在嵌套对象中定义字段?

• Set serializer geo_field as PointField from another model - Django
• Django REST Framework: define fields in nested object?

我有一个Location模型，其中装有SRID = 4326的pointfield.我也有一个TrainStation模型，该模型具有location字段作为的外键.当我通过GeoFeatureModelSerializer序列化TrainStation时，它将生成无效的GeoJSON(请参见无效的geojson"下面的示例).

I have a Location model that holds a pointfield with SRID=4326. I also have a TrainStation model that has location field as foreign key to Location. When I serialize the TrainStation via the GeoFeatureModelSerializer it produces invalid GeoJSON (see example below "invalid geojson").

(如果我将PointField存储在TrainStation模型中，当然可以获得有效的GeoJSON，但就我而言，我不能这样做，所以我需要以某种方式对其进行展平.)

(Valid GeoJSON can, of course, be obtained if I where to store the PointField in the TrainStation model, but in my case, I cannot do that so I need to flatten it somehow.)

• 如何实现类似下面的"Valid GeoJSON"示例的输出?

我是Python和Django的新手，因此我还不太擅长阅读其他人的源代码，但是我想我可以得出结论，我需要以某种方式重写to_representation()方法以获取我想要的东西，但到目前为止，我的搜索无济于事，所以被困了.

I am a newcomer to both Python and Django thus I am yet not very good at reading other people's source code, however I think I can conclude that I need to somehow override the to_representation() method in order to get what I want, but my searches are so far fruitless so I am stuck.

class Location(models.Model):

    point = models.PointField()

class TrainStation(models.Model):

    location_signature = models.CharField(primary_key=True, max_length=32)
    advertised_location_name = models.CharField(max_length=32)
    country_code = models.ForeignKey(Country)
    county_no = models.ForeignKey(County)
    location = models.ForeignKey(Location, null=True)

serializers.py

class LocationSerializer(ModelSerializer):

    class Meta:
        model = Location
        geo_field = 'point'
        fields = [
            'point',
        ]


class TrainStationSerializer(GeoFeatureModelSerializer):

    location_signature = PrimaryKeyRelatedField(read_only=True)
    location = LocationSerializer(read_only=True)
    country_code = StringRelatedField(read_only=True)
    county_no = StringRelatedField(read_only=True)

    class Meta:
        model = TrainStation
        geo_field = 'location'
        fields = [
            'location_signature',
            'advertised_location_name',
            'country_code',
            'county_no',
        ]

GeoJSON输出示例:

我已经验证了 http://geojson.io 上的输出，以确定其是否有效.

GeoJSON Output examples:

I have verified the output on http://geojson.io to determine if its valid or not.

{
    "type": "FeatureCollection",
    "features": [
        {
            "id": "Ak",
            "type": "Feature",
            "geometry": {
                "point": {           <------+------ offending lines
                    "type": "Point",        |
                    "coordinates": [        |
                        18.8303462142963,   |
                        68.3486410812835    |
                    ]                       |
                }                    <------+
            },
            "properties": {
                "advertised_location_name": "Abisko Östra",
                "country_code": "Sverige",
                "county_no": "Norrbottens län"
            }
        }
    ]
}

有效的GeoJSON

这是我正在寻找的输出.

Valid GeoJSON

This is the output I am looking for.

{
    "type": "FeatureCollection",
    "features": [
        {
            "id": "Ak",
            "type": "Feature",
            "geometry": {
                "type": "Point",
                "coordinates": [
                    18.8303462142963,
                    68.3486410812835
                ]
            },
            "properties": {
                "advertised_location_name": "Abisko Östra",
                "country_code": "Sverige",
                "county_no": "Norrbottens län"
            }
        }
    ]
}

推荐答案

我现在使用以下代码解决了这个问题:

I have now solved this issue with the following code:

class LocationSerializer(ModelSerializer):

    def to_representation(self, obj):

        representation = super().to_representation(obj)
        point_representation = representation.pop('point')
        for key in point_representation:
            representation[key] = point_representation[key]

        return representation

    class Meta:
        model = Location
        geo_field = 'point'
        fields = [
            'point',
        ]

这确实会产生有效的GeoJSON:

And this does indeed produce valid GeoJSON:

{
    "type": "FeatureCollection",
    "features": [
        {
            "id": "Ak",
            "type": "Feature",
            "geometry": {
                "type": "Point",
                "coordinates": [
                    18.8303462142963,
                    68.3486410812835
                ]
            },
            "properties": {
                "advertised_location_name": "Abisko Östra",
                "country_code": "Sverige",
                "county_no": "Norrbottens län"
            }
        }
    ]
}

如果有人对此有任何投入，请随时做出贡献并添加答案:-)

If someone has any inputs on this feel free to contribute and add an answer :-)

这篇关于如何使用django-rest-framework-(gis)压平外键对象的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！