Set up database with Prisma ORM (#13)

Co-authored-by: Gabriel Majeri <gabriel.majeri6@gmail.com>

.env.development

@@ -3,3 +3,6 @@ NEXTAUTH_URL=http://localhost:3000
 
 # Configure a secret key for encrypting session tokens
 NEXTAUTH_SECRET=dev
+
+# Connection string for Prisma
+DATABASE_URL="postgresql://taxes_app:dev_pwd@localhost:5432/taxes?schema=public"

.gitignore

@@ -25,6 +25,9 @@ npm-debug.log*
 yarn-debug.log*
 yarn-error.log*
 
+# root env file
+.env
+
 # local env files
 .env*.local
 

README.md

@@ -13,17 +13,49 @@ This app enables the online payment of admission/accomodation/study taxes at the
 
 ## Development instructions
 
+### Dependencies
+
 You need to have the latest stable versions of [Node.js](https://nodejs.org/en) and [npm](https://www.npmjs.com/) installed.
 
 If it is the first time you're running the app, you will have to install all of the required package dependencies by running `npm install` in the root directory.
 
+### Database setup
+
 The app requires a [PostgreSQL](https://www.postgresql.org/) database to be available. The easiest way to spin up one locally is by installing [Docker](https://www.docker.com/) and then running:
 
 ```bash
 docker compose up
 ```
 
-in this directory.
+[Prisma](https://www.prisma.io/) is our chosen [ORM](https://en.wikipedia.org/wiki/Object%E2%80%93relational_mapping). Some useful commands:
+
+- To use the Prisma CLI with the development database:
+
+  ```bash
+  npm run prisma
+  ```
+
+- To initialize the database, or to push changes without creating a migration:
+
+  ```bash
+  npm run prisma:push
+  ```
+
+- To synchronize the database and create a migration:
+
+  ```bash
+  npm run prisma:migrate --name "migration name"
+  ```
+
+- To generate or update the Prisma client:
+
+  ```bash
+  npm run prisma:generate
+  ```
+
+  This step is required after every schema change, because the Prisma client is dynamically generated and stored in a subdirectory of the `node_modules` folder, which is not commited into version control.
+
+### Authentification config
 
 The app uses [NextAuth.js](https://next-auth.js.org/) to provide support for authentication using [Microsoft Entra ID (formerly Azure AD)](https://www.microsoft.com/en-us/security/business/identity-access/microsoft-entra-id). In development, you have to create a `.env.local` file in the root directory and define the following environment variables:
 
@@ -33,6 +65,8 @@ AZURE_AD_CLIENT_ID=<client ID of app registration>
 AZURE_AD_CLIENT_SECRET<client secret created for app>
 ```
 
+### Useful development commands
+
 To start a local development server, use:
 
 ```bash