how to do Django query that is ordered by latlng string-CodePudding

Current Situation

I Am fetching data that contains Strings that represent the Latlng of some locations .. like 30.78829892811801,31.2769004988329 30.78848118485095,31.27649189363398 30.78869531217787,31.27615745128788 etc.

What I have tried

now I am doing Django query like ModelName.objects.all().order_by('latlng') but it is not ordering it as the field is simply a Charfield .. also converting it to double is not working as it contains 2 different double separated by the comma.

What I need to do

Is there a way to convert this string to LatLng that is orderable by location or something like this?

CodePudding user response：

Are you using Postgres? If so, you can use the ArrayField to split out your string into an array that might make it more easily-sortable in the ORM.

from django.db.models import F, Value, DecimalField
from django.db.models.expressions import Func
from django.contrib.postgres.fields import ArrayField

latlng_arr_func = Func(
    F('latlng'),
    Value(","),
    function='regexp_split_to_array', output=ArrayField(DecimalField())
)

ModelName.objects.annotate(latlng_arr=latlng_arr_func).order_by('-latlng_arr')

Then calling object.latlng_arr should yield a list of your values [30.78829892811801,31.2769004988329].

If this doesn't get you the result you want then I would suggest either splitting the data into two decimal fields on your model (you could still keep the string version) or order the data using Python.