GeoFlask - Backend API

Description

A Flask app that uses PostgreSQL with PostGIS for geospatial data, providing endpoints for querying and uploading polygon GeoJSON data.

Route	Function
GET /ping	returns "pong"
POST /upload	insert new geojson
GET /geojson	returns geojson

Dependencies

Python 3.10.12 and requirements.txt

Getting Started

Lores ipsum

Flask-Migrate

To Flask-Migrate's Alembic properly work with geoalchemy2 and sqlachemy, declare any geometry column with spatial_index=False and add the spatial_index explicitly.

Or make sure to ignore in the migrations/env.py objects that are "idx_%_geom" but this imply having all your geometry columns named the same.

Tests

Run tests with pytest --cov=app tests/ -v

Run flask

flask --app app run --debug

Database

Database - install DB in WSL

# Start from scratch without any conflict
sudo apt-get --purge remove postgresql postgresql-common postgresql-client postgresql-contrib postgis
sudo apt-get autoremove

# Install
sudo apt update
sudo apt-get install postgresql postgresql-contrib postgis 

# Check status
sudo service postgresql status

# Enter
sudo -u postgres psql -f comando.sql

Create the database

-- Create DATABASE with postgis and SUPERUSER
CREATE DATABASE <FLASK_DB_NAME>;
CREATE ROLE <FLASK_DB_USERNAME> WITH LOGIN PASSWORD <FLASK_DB_PASSWORD> SUPERUSER;
GRANT ALL PRIVILEGES ON DATABASE <FLASK_DB_NAME> TO <FLASK_DB_USERNAME>;

\c <FLASK_DB_NAME>
CREATE EXTENSION postgis;

Flask-Migrate

On the first migration, run

# Init fladk db from scratch
rm -r migrations/*
flask db init

Edit migrations/script.py.mako by adding import geoalchemy2 to tell Alembic you have geoalchemy2 geometry columns

# ...
from alembic import op
import sqlalchemy as sa
import geoalchemy2
${imports if imports else ""}
# ...

Edit migrations/env.py to ignore postgis tables

def get_metadata():
# ...

def include_object(object, name, type_, reflected, compare_to):    
    if type_ == "table" and name == 'spatial_ref_sys':
        return False
    else:
        return True


def run_migrations_offline():
    # ...
    context.configure(
        # ...
        include_object=include_object       # <--- HERE
        )
    # ...

def run_migrations_online():
    # ...
    with connectable.connect() as connection:
        context.configure(
            # ...
            include_object=include_object
        )

# Choose your .env names wise.
# flask overwrites "DATABASE_HOSTNAME"
flask db migrate -m "Initial migration."
flask db upgrade

About Alembic and custom types

Why and what are the effect of?
scope=session (conftest)