database-generic

Database-agnostic interface to generically persisted data.

Introduction

Explanation of the above:

• Database-agnostic: the typeclass is called MonadDb, and you must specify how an instance can communicate with your database. We provide an example for connecting to Postgres in the runnable tutorial.
• Generically persisted data: you can derive the necessary instances in one line via Generics, to enable MonadDb to read/write instances of your data types to/from your database.

A key intended feature of this library is that the typeclass MonadDb can be used either server-side or client-side. Allowing your client application (e.g. web app) to use the same functions to access your data as your server-side does.

Another important intended feature is an optional servant server. Merely provide an instance of MonadDb so the server knows how to communicate with your database, then the server can act as a proxy to allow clients to read/write to your database without having to write the usual server boilerplate.

Quick Start

The runnable tutorial is the recommended way of becoming familiar with database-generic.

To run the tutorial on your machine:

1. Clone this repo.
2. Start a PostgreSQL instance with username and password demo, e.g.: docker run -it --rm --env POSTGRES_PASSWORD=demo --env POSTGRES_USER=demo --publish 5432:5432 postgres
3. Then cabal run tutorial via provided nix-shell.

Features

Examples of the following features can be found in the tutorial.

Feature	In Tutorial	Tested
Create table	✅	✅
Insert one	✅
Insert many	✅
Insert returning	✅
Insert returning fields	✅	✅
Select by PK	✅	✅
Select all	✅	✅
Select returning fields	✅	✅
Where column equals
Where column is null
Where column is not null
Limit clause	✅	✅
Offset clause	✅	✅
Order by clause	✅	✅
Delete by PK	✅	✅
Delete all	✅	✅
Delete returning	✅	✅
Server: endpoint to execute statement	✅
Joins
Stream statements over Conduit
Stream updates over Conduit
Server: stream statements over WebSocket
Server: stream updates over WebSocket
Server: permission checks
Reflex (client-side) MonadDb instance