CAPE Environment Database Repo

TBD blah blah repo for the main cape environment database

Setup

Local postgresql

Installation

We are using version 18.x. Installation instructions are provided by the community for various platforms

perms to allow database operations

Just so it's said, these are dev only operations. Don't do this in anything but your test system.

# connect to postgres as default user
sudo -iu postgres psql

# replace <username> with your username in all of the below. you can do this
# however you want if you know what you're doing, username stuff just makes
# things quick for development.

# create a group for granting some types of access
postgres=# create role <username>_group nologin;

# grant the group total select on the public schema
postgres=# grant select on all tables in schema public to <username>_group;

# and all future tables in the group
postgres=# alter default privileges in schema public grant select on tables to <username>_group;

# and usage on the public schema in general
postgres=# grant usage on schema public to <username>_group;

# now your user
postgres=# create role <username> with login;

# let your user create databases
postgres=# alter user <username> createdb;

# create the cape db so we can grant some perms there
postgres=# create database cape_env_db;

# allow create of this database - not strictly necessary since this user has
# been granted createdb
postgres=# grant create on database cape_env_db to <username>;

# allow connect to this database
postgres=# grant connect on database cape_env_db to <username>;

# make your user owner of the db
postgres=# alter database cape_env_db owner to <username>;

postgres=# exit

# at this point you should be able to connect to the cape_env_db as yourself with no password.
14:43 $ psql cape_env_db

repo

Users of mise en place or asdf can use the .tool-versions and mise.toml provided. For those managing software in other manners, the software requirements are as follows:

• python 3.10+
• poetry 2.3+
• items in pyproject.toml (installed via poetry install)

Setup DB

This package provides the capedb script to handle DB upgrades, downgrades and checking of current version. All other alembic commands (including upgrades, downgrades and checking of current version) can be accomplished via normal alembic means.

NOTE: At this point we expect an empty database to exist before we apply migrations or create tables. This could change in the future, but for now it's a requirement. If you followed the postgres setup above you have already done this.

Alembic Config

Usage of the capedb script requires an alembic config file be available. This can be accomplished in a number of ways:

• have it available in the current working directory when executing the capedb script (it will be found automatically)
• specification on the command line when calling capedb: capedb [-c | --config <CONFIG_PATH>]
• specifying the location in the ALEMBIC_CONFIG environment variable

NOTE: However the alembic.ini is specified, the value of script_location needs to point to the migrations directory of this package. This is most likely <python_site_package_dir>/cape_cod_db/migrations if you are using an installed version of this package. The <python_site_package_dir>/cape_cod_db directory also contains an alembic.ini that can be used if defaults are fine, though you will want to specify the database url as detailed below if you use the builtin config file.

Database URL

Though the database url is often defined in the alembic config, if you also need to specify it separately you also have a few options:

• specification on the command line when calling capedb: capedb [-x db_url=<DB_URL>]
• specifying the location in the DB_URL environment variable

capedb Script Usage

Run the alembic migrations on the empty (or previously upgraded) db to get up to date capedb upgrade head. NOTE: head can be replaced with another revision identifier to go to a specific version.

Downgrades can be performed via capedb downgrade <revision>.

The current version can be determined with capedb current [--verbose].

capedb-app script

This is probably not anything you want to use. Probably.

This is the more traditional app.py like mechanism to create database tables. This is not compatible with our provided migrations either. If you wish to create an empty database using only the most schema in this version of this package without any migration information, this is your boo. But you would have to maintain your own migrations at that point. If you are maintaining migrations ever.

This script requires the DB_URL environment variable be set and does not work with alembic at all, so the alembic config is not needed.

Play With The DB

From repo root in the python repl of your fancy (that has all the dependencies installed).

import cape_cod_db
from sqlmodel import select, Session
from cape_cod_db import database as db
from cape_cod_db import models

# add a user
with Session(db.engine) as session:
    usr = models.User(
        first_name="First", last_name="Last", email="fl@fakeemail.test"
    )
    session.add(usr)
    session.commit()

# list the users in the db
with Session(db.engine) as session:
    stmnt = select(models.User)
    res = session.exec(stmnt)

    for u in res.all():
        print(u)

# update the user
with Session(db.engine) as session:
    usr_stmnt = select(models.User).where(
        models.User.first_name == "First", models.User.last_name == "Last"
    )
    usr = session.exec(usr_stmnt).first()
    usr.first_name = "Furst"
    session.add(usr)
    session.commit()

# list them again to show the first name and modified time have changed.
with Session(db.engine) as session:
    stmnt = select(models.User)
    res = session.exec(stmnt)

    for u in res.all():
        print(u)

If you prefer psql (NOTE: this assumes you have all the perms on the db):

12:12 $ psql cape_env_db


psql (18.3)
Type "help" for help.

cape_env_db=> \d+
                                          List of relations
 Schema |      Name       |   Type   | Owner | Persistence | Access method |    Size    | Description
--------+-----------------+----------+-------+-------------+---------------+------------+-------------
 public | alembic_version | table    | xxxx  | permanent   | heap          | 8192 bytes |
 public | user            | table    | xxxx  | permanent   | heap          | 16 kB      |
 public | user_id_seq     | sequence | xxxx  | permanent   |               | 8192 bytes |

cape_env_db=> \d user
                                         Table "public.user"
   Column    |            Type             | Collation | Nullable |             Default
-------------+-----------------------------+-----------+----------+----------------------------------
 created_at  | timestamp without time zone |           | not null |
 last_edited | timestamp without time zone |           | not null |
 id          | integer                     |           | not null | nextval('user_id_seq'::regclass)
 first_name  | character varying           |           | not null |
 last_name   | character varying           |           | not null |
 email       | character varying           |           | not null |

cape_env_db=> select * from alembic_version;
 version_num
--------------
 6001985fea71
(1 row)

# NOTE that if you manipulate records via sql, the created_at and last_edited
# **ARE NOT HANDLED FOR YOU**

cape_env_db=> insert into public.user (created_at, last_edited, first_name, last_name, email) values (now(), now(), 'First', 'Last', 'fl@fakeemail.test');
INSERT 0 1
cape_env_db=> select * from public.user;
         created_at         |        last_edited         | id | first_name | last_name |       email
----------------------------+----------------------------+----+------------+-----------+-------------------
 2026-03-05 13:55:21.688756 | 2026-03-05 13:55:21.688756 |  2 | First      | Last      | fl@fakeemail.test
(1 row)