Supabase JS
BemiHQ/bemi-supabase-jsBemi plugs into Supabase JS and PostgreSQL to track database changes automatically. It unlocks robust context-aware audit trails and time travel querying inside your application.
This package is a recommended Supabase JS integration, enabling you to pass application-specific context when performing database changes. This can include context such as the 'where' (API endpoint, worker, etc.), 'who' (user, cron job, etc.), and 'how' behind a change, thereby enriching the information captured by Bemi.
See this example repo as an Todo app example with Supabase JS that automatically tracks and contextualizes all changes.
Prerequisites
- Supabase JS
Installation
- Install the NPM package
npm install @bemi-db/supabase-js
- Generate a Supabase JS migration file to add a Database Function for passing application context with all data changes into PostgreSQL replication log
npx bemi migration new
- Run the Supabase JS migration
npx supabase migration up
Usage
Now you can easily specify custom application context that will be automatically passed with all data changes by calling setContext
in your Supabase Edge Function:
import { setContext } from 'https://esm.sh/@bemi-db/[email protected]'
import { createClient } from 'https://esm.sh/@supabase/[email protected]'
Deno.serve(async (req) => {
const supabase = createClient(...)
const { method, url } = req
const endpoint = `/${url.split('/')[3]}`
const payload = method === 'POST' ? await req.json() : {}
// Customizable context
await setContext(supabase, { method, endpoint, payload })
// Your code that performs data changes
})
Application context:
- Is bound to the current database session within an HTTP request.
- Is used only with
INSERT
,UPDATE
,DELETE
SQL queries performed via Supabase JS. - Is passed directly into PG Write-Ahead Log with data changes without affecting the structure of the database and SQL queries.
Data change tracking
Local database
To test data change tracking and the Supabase JS integration with a locally connected PostgreSQL, you need to set up your local PostgreSQL.
First, make sure your database has SHOW wal_level;
returning logical
. Otherwise, you need to run the following SQL command:
-- Don't forget to restart your PostgreSQL server after running this command
ALTER SYSTEM SET wal_level = logical;
To track both the "before" and "after" states on data changes, please run the following SQL command:
ALTER TABLE [YOUR_TABLE_NAME] REPLICA IDENTITY FULL;
Then, run a Docker container that connects to your local PostgreSQL database and starts tracking all data changes:
docker run \
-e DB_HOST=host.docker.internal \
-e DB_PORT=5432 \
-e DB_NAME=[YOUR_DATABASE] \
-e DB_USER=postgres \
-e DB_PASSWORD=postgres \
public.ecr.aws/bemi/dev:latest
Replace DB_NAME
with your local database name. Note that DB_HOST
pointing to host.docker.internal
allows accessing 127.0.0.1
on your host machine if you run PostgreSQL outside Docker. Customize DB_USER
and DB_PASSWORD
with your PostgreSQL credentials if needed.
Now try making some database changes. This will add a new record in the changes
table within the same local database after a few seconds:
psql postgres://postgres:[email protected]:5432/[YOUR_DATABASE] -c \
'SELECT "primary_key", "table", "operation", "before", "after", "context", "committed_at" FROM changes;'
primary_key | table | operation | before | after | context | committed_at
-------------+-------+-----------+----------------------------------------------------+-----------------------------------------------------+-------------------------------------------------------------------------------------------+------------------------
26 | todo | CREATE | {} | {"id": 26, "task": "Sleep", "is_completed": false} | {"user_id": 187234, "endpoint": "/todo", "method": "POST", "SQL": "INSERT INTO ..."} | 2023-12-11 17:09:09+00
27 | todo | CREATE | {} | {"id": 27, "task": "Eat", "is_completed": false} | {"user_id": 187234, "endpoint": "/todo", "method": "POST", "SQL": "INSERT INTO ..."} | 2023-12-11 17:09:11+00
28 | todo | CREATE | {} | {"id": 28, "task": "Repeat", "is_completed": false} | {"user_id": 187234, "endpoint": "/todo", "method": "POST", "SQL": "INSERT INTO ..."} | 2023-12-11 17:09:13+00
26 | todo | UPDATE | {"id": 26, "task": "Sleep", "is_completed": false} | {"id": 26, "task": "Sleep", "is_completed": true} | {"user_id": 187234, "endpoint": "/todo/complete", "method": "PUT", "SQL": "UPDATE ..."} | 2023-12-11 17:09:15+00
27 | todo | DELETE | {"id": 27, "task": "Eat", "is_completed": false} | {} | {"user_id": 187234, "endpoint": "/todo/27", "method": "DELETE", "SQL": "DELETE FROM ..."} | 2023-12-11 17:09:18+00
Remote database
Go to Bemi.io Dashboard UI and follow the instructions to connect your hosted PostgreSQL database in a few seconds.
Once the project infrastructure is provisioned, it'll automatically ingest and store all data changes stitched with an application context in a separate serverless PostgreSQL database. You can test the connection by running the following command:
psql postgres://[USERNAME]@[HOSTNAME]:5432/[DATABASE] -c \
'SELECT "primary_key", "table", "operation", "before", "after", "context", "committed_at" FROM changes;'
primary_key | table | operation | before | after | context | committed_at
-------------+-------+-----------+----------------------------------------------------+-----------------------------------------------------+-------------------------------------------------------------------------------------------+------------------------
26 | todo | CREATE | {} | {"id": 26, "task": "Sleep", "is_completed": false} | {"user_id": 187234, "endpoint": "/todo", "method": "POST", "SQL": "INSERT INTO ..."} | 2023-12-11 17:09:09+00
27 | todo | CREATE | {} | {"id": 27, "task": "Eat", "is_completed": false} | {"user_id": 187234, "endpoint": "/todo", "method": "POST", "SQL": "INSERT INTO ..."} | 2023-12-11 17:09:11+00
28 | todo | CREATE | {} | {"id": 28, "task": "Repeat", "is_completed": false} | {"user_id": 187234, "endpoint": "/todo", "method": "POST", "SQL": "INSERT INTO ..."} | 2023-12-11 17:09:13+00
26 | todo | UPDATE | {"id": 26, "task": "Sleep", "is_completed": false} | {"id": 26, "task": "Sleep", "is_completed": true} | {"user_id": 187234, "endpoint": "/todo/complete", "method": "PUT", "SQL": "UPDATE ..."} | 2023-12-11 17:09:15+00
27 | todo | DELETE | {"id": 27, "task": "Eat", "is_completed": false} | {} | {"user_id": 187234, "endpoint": "/todo/27", "method": "DELETE", "SQL": "DELETE FROM ..."} | 2023-12-11 17:09:18+00
See Destination Database for more details.
See Destination Database for more details.
License
Distributed under the terms of the LGPL-3.0. If you need to modify and distribute the code, please release it to contribute back to the open-source community.