我正在尝试使用geojson序列化程序绘制地图中的纬度点。对于此功能，我有两个模型，名为Activity和ClusterA.
活动是存储项目中定义的某些活动的数据的模型。此活动包含一个名为location的PointField字段。 这是我Activity模型：
class Activity(models.Model):
name = models.CharField(max_length=200)
description = models.CharField(max_length=500)
target_number = models.IntegerField(null=True, blank=True)
target_unit = models.CharField(max_length=200, null=True, blank=True)
beneficiary_level = models.BooleanField(default=True)
weight = models.FloatField(default=0)
location = PointField(geography=True, srid=4326, blank=True, null=True)
def __str__(self):
return self.name
@property
def latitude(self):
if self.location:
return self.location.y
@property
def longitude(self):
if self.location:
return self.location.x
同样，活动可以属于群集。此数据存储在模型ClusterA(群集活动)中。群集 A是指特定于群集的活动。
集群模型
class Cluster(models.Model):
name = models.CharField(max_length=200)
ward = models.CharField(max_length=200)
def __str__(self):
return self.name
聚类 A 模型
class ClusterA(models.Model):
activity = models.ForeignKey('Activity', related_name='clustera')
target_number = models.IntegerField(null=True, blank=True, default=0)
target_unit = models.CharField(max_length=200, null=True, blank=True, default='')
time_interval = models.ForeignKey(ProjectTimeInterval, related_name='cainterval', null=True, blank=True)
target_completed = models.IntegerField(null=True, blank=True, default=0)
interval_updated = models.BooleanField(default=False)
target_updated = models.BooleanField(default=False)
location = PointField(geography=True, srid=4326, blank=True, null=True)
def __str__(self):
return self.name
@property
def latitude(self):
if self.location:
return self.location.y
@property
def longitude(self):
if self.location:
return self.location.x
def save(self, force_insert=False, force_update=False, using=None, update_fields=None):
if not self.id:
if not self.activity.beneficiary_level:
self.target_unit = self.activity.target_unit
self.time_interval = self.activity.time_interval
return super(ClusterA, self).save()
现在，我正在使用一个函数，该函数将群集活动的 geojson 数据返回为：
def get_map_data(request):
ca = ClusterA.objects.all()
data = serialize(
'geojson',
ca,
geometry_field='location',
fields = ('activity', 'location', )
)
print(data)
return HttpResponse(data)
我得到的输出是：
{"type": "FeatureCollection", "crs": {"type": "name", "properties": {"name": "EPSG:4326"}}, "features": [{"geometry": {"type": "Point", "coordinates": [85.336775, 27.542718]}, "type": "Feature", "properties": {"activity": 27}}, {"geometry": null, "type": "Feature", "properties": {"activity": 19}}, {"geometry": {"type": "Point", "coordinates": [85.336776, 27.735227]}, "type": "Feature", "properties": {"activity": 26}}]}
活动字段提供活动的ID。但是我需要活动名称，以便我可以在地图中绘制的标记弹出窗口中显示活动名称。
这就是我尝试在标记弹出窗口中显示活动名称的方式：
onEachFeature: function (feature, layer) {
layer.bindPopup(feature.properties.name);
}
如果我将本地模型的字段传递给它，弹出窗口会显示其他数据。
我试过使用：
fields = ('activity__name', 'location', )
在get_map_data函数中，但它不会将打印输出中的字段显示为：
{
"type": "FeatureCollection",
"crs": {
"type": "name",
"properties": {
"name": "EPSG:4326"
}
},
"features": [
{
"geometry": {
"type": "Point",
"coordinates": [
85.336775,
27.542718
]
},
"type": "Feature",
"properties": {
}
},
{
"geometry": null,
"type": "Feature",
"properties": {
}
},
{
"geometry": {
"type": "Point",
"coordinates": [
85.336776,
27.735227
]
},
"type": "Feature",
"properties": {
}
}
]
}
如您所见，上述输出的properties中没有指定字段。
我需要的帮助是能够获取活动模型的名称字段而不是 id。
我正在使用Django 1.8.
编辑：添加select_related后打印(ca.dict)的输出
{'activity_id': 44,
'target_unit': u'Check',
'_state': <django.db.models.base.ModelState object at 0x7f57e19c8150>,
'target_completed': 0,
'cag_id': 35,
'target_updated': False,
'_activity_cache': <Activity: Test>,
'location': <Point object at 0x7f57e19391c0>,
'time_interval_id': 84,
'target_number': 12,
'interval_updated': False,
'id': 72}
自定义序列化程序的错误回溯
ERROR 2019-06-12 14:40:15,638 base 27641 140154705491712 Internal Server Error: /core/get-map-data/
Traceback (most recent call last):
File "/home/sanip/.virtualenvs/mes/lib/python2.7/site-packages/django/core/handlers/base.py", line 132, in get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/home/sanip/naxa/mes-core/onadata/apps/core/views.py", line 366, in get_map_data
data = serializers.serialize(ca, geometry_field='location', fields=('activity__name', 'location',))
File "/home/sanip/.virtualenvs/mes/lib/python2.7/site-packages/django/core/serializers/base.py", line 69, in serialize
self.end_object(obj)
File "/home/sanip/naxa/mes-core/onadata/apps/core/serializers.py", line 170, in end_object
super(CustomSerializer, self).end_object(obj)
File "/home/sanip/.virtualenvs/mes/lib/python2.7/site-packages/django/core/serializers/json.py", line 61, in end_object
cls=DjangoJSONEncoder, **self.json_kwargs)
File "/usr/lib/python2.7/json/__init__.py", line 189, in dump
for chunk in iterable:
File "/usr/lib/python2.7/json/encoder.py", line 434, in _iterencode
for chunk in _iterencode_dict(o, _current_indent_level):
File "/usr/lib/python2.7/json/encoder.py", line 408, in _iterencode_dict
for chunk in chunks:
File "/usr/lib/python2.7/json/encoder.py", line 408, in _iterencode_dict
for chunk in chunks:
File "/usr/lib/python2.7/json/encoder.py", line 442, in _iterencode
o = _default(o)
File "/home/sanip/.virtualenvs/mes/lib/python2.7/site-packages/django/core/serializers/json.py", line 115, in default
return super(DjangoJSONEncoder, self).default(o)
File "/usr/lib/python2.7/json/encoder.py", line 184, in default
raise TypeError(repr(o) + " is not JSON serializable")
TypeError: <Point object at 0x7f783f0c92e0> is not JSON serializable
Internal Server Error: /core/get-map-data/
Traceback (most recent call last):
File "/home/sanip/.virtualenvs/mes/lib/python2.7/site-packages/django/core/handlers/base.py", line 132, in get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/home/sanip/naxa/mes-core/onadata/apps/core/views.py", line 366, in get_map_data
data = serializers.serialize(ca, geometry_field='location', fields=('activity__name', 'location',))
File "/home/sanip/.virtualenvs/mes/lib/python2.7/site-packages/django/core/serializers/base.py", line 69, in serialize
self.end_object(obj)
File "/home/sanip/naxa/mes-core/onadata/apps/core/serializers.py", line 170, in end_object
super(CustomSerializer, self).end_object(obj)
File "/home/sanip/.virtualenvs/mes/lib/python2.7/site-packages/django/core/serializers/json.py", line 61, in end_object
cls=DjangoJSONEncoder, **self.json_kwargs)
File "/usr/lib/python2.7/json/__init__.py", line 189, in dump
for chunk in iterable:
File "/usr/lib/python2.7/json/encoder.py", line 434, in _iterencode
for chunk in _iterencode_dict(o, _current_indent_level):
File "/usr/lib/python2.7/json/encoder.py", line 408, in _iterencode_dict
for chunk in chunks:
File "/usr/lib/python2.7/json/encoder.py", line 408, in _iterencode_dict
for chunk in chunks:
File "/usr/lib/python2.7/json/encoder.py", line 442, in _iterencode
o = _default(o)
File "/home/sanip/.virtualenvs/mes/lib/python2.7/site-packages/django/core/serializers/json.py", line 115, in default
return super(DjangoJSONEncoder, self).default(o)
File "/usr/lib/python2.7/json/encoder.py", line 184, in default
raise TypeError(repr(o) + " is not JSON serializable")
TypeError: <Point object at 0x7f783f0c92e0> is not JSON serializable
默认情况下，django 序列化程序不提供 ForeignKey 值。因此，您可以覆盖 geojson 序列化程序字段。例如：
from django.contrib.gis.serializers.geojson import Serializer
class CustomSerializer(Serializer):
def end_object(self, obj):
for field in self.selected_fields:
if field == 'pk':
continue
elif field in self._current.keys():
continue
else:
try:
if '__' in field:
fields = field.split('__')
value = obj
for f in fields:
value = getattr(value, f)
if value != obj:
self._current[field] = value
except AttributeError:
pass
super(CustomSerializer, self).end_object(obj)
用法：
serializers = CustomSerializer()
ca = ClusterA.objects.all()
data = serializers.serialize(ca, geometry_field='location', fields=('activity__name', 'location', ))
我相信您需要做的就是使用.select_related()属性JOIN活动表：
def get_map_data(request):
ca = ClusterA.objects.all().select_related()
data = serialize(
'geojson',
ca,
geometry_field='location',
fields = ('activity', 'location', )
)
让我知道当你尝试这个时会发生什么。
如果这不起作用，请尝试：
def get_map_data(request):
ca = ClusterA.objects.all().select_related('activity__name')
data = serialize(
'geojson',
ca,
geometry_field='location',
fields = ('activity', 'location', )
)