我正在尝试在postgresql数据库上运行迁移，我正在使用python flask。出现以下错误：
类型“几何”不存在
迁移是：
"""empty message
Revision ID: a9d0c3e2ac85
Revises: 06493ef33fab
Create Date: 2016-08-28 01:00:41.022063
"""
# revision identifiers, used by Alembic.
revision = 'a9d0c3e2ac85'
down_revision = '06493ef33fab'
from alembic import op
import sqlalchemy as sa
import geoalchemy2
def upgrade():
### commands auto generated by Alembic - please adjust! ###
op.add_column('location', sa.Column('coordinates', geoalchemy2.types.Geometry(geometry_type='POINT'), nullable=True))
### end Alembic commands ###
def downgrade():
### commands auto generated by Alembic - please adjust! ###
op.drop_column('location', 'coordinates')
### end Alembic commands ###
我的架构是这样的：
import enum
from .extensions import db
from sqlalchemy import func
from sqlalchemy.ext.declarative import declared_attr
from geoalchemy2 import Geometry
class Location(db.Model, Entity):
name = db.Column(db.String(30))
coordinates = db.Column(Geometry('POINT'))