How to define a geometry field with Peewee Models - postgresql

Question

I have looked at examples online on how to create a geometry field with peewee and this is what I came up with so far:
class GeometryField(Field):
db_field = 'geometry'
def db_value(self, value):
return fn.ST_GeomFromGeoJSON(value)
def python_value(self, value):
return fn.ST_AsGeoJSON(value)
I have added this definition to a table like so:
class GeoJSON(BaseModel):
geojson_id = UUIDField(primary_key=True, default=uuid.uuid4)
geometry = GeometryField()
Now, this thing wouldn't run and I don't understand what I missed to make it happen.
My aim is to manage insertions of geometric entities into the DB so that later I can make use of PostGIS to query based on locations.
The error I'm getting in the init phase:
peewee.ProgrammingError: syntax error at or near "NOT" LINE 1:
...geojson_id" UUID NOT NULL PRIMARY KEY, "geometry" NOT NULL)
I init the table like so:
GeoJSON.create_table("geojsons")
What did I miss here? Did I need to do anything else before this geometryfield can be used?
Is there a secret geom field that Peewee supports out of the box that I don't know about?

Answer 1

The problem was that the DB failed to install PostGIS and therefore didn't recognize the geometry field from the DB.
Once I fixed that and had the extension installed, the solution above worked perfectly.

Answer 2

If you are coming back to this question later. The Peewee Syntax has changed since version 3.0. db_field has changed to field_type.
So to get it working:
Make sure you install the PostGIS extension on your postgres database.
CREATE EXTENSION postgis;
Create a custom field.
class GeometryField(Field):
field_type = 'geometry'
def db_value(self, value):
return fn.ST_GeomFromGeoJSON(value)
def python_value(self, value):
return fn.ST_AsGeoJSON(value)
Use the custom field in your model
class GeoJSON(BaseModel):
geojson_id = UUIDField(primary_key=True, default=uuid.uuid4)
geometry = GeometryField()
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