如何根据经度和纬度过滤geodjango [英] How to filter geodjango based on longitude and latitude

问题描述

我有一个已经存储了经度和纬度的应用程序，现在我想将其与geodjango集成，该应用程序看起来像这样。

I have an application that has been storing longitude and latitude now i want to integrate it with geodjango the application looks like this.

class Location(models.Model):
    #other fields here
    lat = models.CharField(blank=True, max_length=100)
    lng = models.CharField(blank=True, max_length=100)

现在我想根据距离过滤位置，例如过滤所有1公里以外的位置使用django.contrib.gis.measure从pk = 1的位置导入D和GEOSGeometry，或者我应该重构模型以具有点而不是经度和纬度，所以我可以做这样的事情：

now I will like to filter locations based on a distance say filter all location 1km away from location with pk = 1 using django.contrib.gis.measure import D and GEOSGeometry or should i refactor the model to have point rather than longitude and latitude so i can do something like this :

Location.objects.filter(point__dwithin=(D(km=5)))

任何建议和建议都可以。

any advice and recommendations will do.

推荐答案

向南使用... 3次迁移以解决此问题。 （链接：如何安装南部]

Using south... it would take 3 migrations to address this. (Link: How to install South]

1）添加名为 point 的 PointField ：

from django.contrib.gis.db import models  <-- NEW

# ...

class Location(models.Model):
    #other fields here
    lat = models.CharField(blank=True, max_length=100)
    lng = models.CharField(blank=True, max_length=100)

    point = models.PointField(null=True)  <-- NEW

---

2）自动执行 schemamigration

patrick@localhost:~$ python manage.py schemamigration my_app_name --auto

---

3）执行自定义的数据迁移，您将在现有的 CharField中的每个元素上创建一个点属性

patrick@localhost:~$ python manage.py datamigration my_app_name latlng_to_point

编辑由 datamigration创建的文件管理命令：

# my_app_name/migrations/0034__latlng_to_point.py

from django.contrib.gis.geos import Point

# ...

class Migration(DataMigration):

    def forwards(self, orm):
        "Write your forwards methods here."
        # Note: Remember to use orm['appname.ModelName'] rather than "from appname.models..."
        for location in orm['my_app_name.Location'].objects.all():
            location.point = Point(float(location.lng), float(location.lat), srid=4326)
            location.save()

    def backwards(self, orm):
        "Write your backwards methods here."
        for location in orm['data.Location'].objects.all():
            location.point = None
            location.save()

---

4）从您的计算机中删除 CharField 建模并删除 null = True ，如果您愿意：

---

4) Delete the CharField from your model and remove null=True if you wish:

class Location(models.Model):
    # other fields here
    # DELETED lat = models.CharField(blank=True, max_length=100)
    # DELETED lng = models.CharField(blank=True, max_length=100)

    point = models.PointField(null=False)  <-- NEW: null=False

---

5）自动创建另一个模式迁移

---

5) Create another schemamigration automatically

patrick@localhost:~$ python manage.py schemamigration my_app_name --auto

---

6）成功运行迁移！这是将更改写入您的数据库等的时间。

---

6) Run the migrations successfully! This is when changes are written to your DB, etc.

patrick@localhost:~$ python manage.py migrate my_app_name

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