In my project I am using PostgreSQL/PostGIS as the database and Django with django.contrib.gis configured. The existing table pois contains geospatial point data. Here is a excerpt from the SQL create statement:
CREATE TABLE pois
(
ogc_fid serial NOT NULL,
the_geom geometry(Point,900914),
name character varying(254),
-- ...
I generated the Django model with the following command:
$ python manage.py inspectdb
The generated model looks like this:
from django.contrib.gis.db import models
class POIs(models.Model):
ogc_fid = models.AutoField(primary_key=True)
the_geom = models.TextField(blank=True, null=True) # This field type is a guess.
name = models.CharField(max_length=254, blank=True, null=True)
class Meta:
managed = False
db_table = 'pois'
I add the following field to overwrite the default manage with a GeoDjango specific instance:
objects = models.GeoManager()
Now, I want to replace the_geom = models.TextField() with the correct data type which should be either models.PointField() or models.GeometryField(). I tried both. Then I test the model at the Python shell:
$ python manage.py shell
Python 3.4.3 (default, Jul 28 2015, 18:20:59)
In [1]: from berlin import models
In [2]: models.POIs.objects.first()
This fails and the following stacktrace is output:
/home/user/.virtualenvs/myproject/lib/python3.4/site-packages/django/contrib/ \
gis/db/models/fields.py in select_format(self, compiler, sql, params)
57 else:
58 sel_fmt = '%s'
---> 59 if connection.ops.select:
60 # This allows operations to be done on fields in the SELECT,
61 # overriding their values -- used by the Oracle and MySQL
AttributeError: 'DatabaseOperations' object has no attribute 'select'
There is no error when I leave the model with models.TextField. Then the string value is output.
The database configuration in settings.py was incorrect:
DATABASES = {
'default': {
'ENGINE': 'django.db.backends.postgresql_psycopg2',
'NAME': 'geodjango',
'USER': 'geo',
'PASSWORD': 'secret',
'HOST': 'localhost',
'PORT': '5432',
}
}
Correct:
DATABASES = {
'default': {
'ENGINE': 'django.contrib.gis.db.backends.postgis', # Here
'NAME': 'geodjango',
'USER': 'geo',
'PASSWORD': 'secret',
'HOST': 'localhost',
'PORT': '5432',
}
}
I have overseen this in the documentation somehow. Thanks to apollo13 from the #django irc channel for the advice into the right direction.
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