Add the ability to customise the Generated Prisma Schema (#8241)

Co-authored-by: Daniel Cousens <413395+dcousens@users.noreply.github.com>
Co-authored-by: Daniel Cousens <dcousens@users.noreply.github.com>

.changeset/pretty-books-pretend.md

@@ -0,0 +1,6 @@
+---
+'@keystone-6/fields-document': minor
+'@keystone-6/core': minor
+---
+
+Adds an experimental `extendPrismaSchema` configuration option for lists and fields to mutate the prisma schema

examples/extend-prisma-schema/README.md

@@ -0,0 +1,28 @@
+## Example Project - Extend Prisma Schema
+
+This project implements an example of mutating the Prisma Schema to:
+
+- Set the Prisma Binary Target;
+- Add a multi-column column unique constraint to a list; and
+- Add a NOT NULL relationship field
+
+These show three separate ways of mutating the Prisma Schema see `keystone.ts` and `schema.ts`.
+
+## Instructions
+
+To run this project, clone the Keystone repository locally, run `yarn` at the root of this repository, then navigate to this directory and run:
+
+```shell
+yarn dev
+```
+
+This will start the Admin UI at [localhost:3000](http://localhost:3000).
+You can use the Admin UI to create items in your database.
+
+You can also access a GraphQL Playground at [localhost:3000/api/graphql](http://localhost:3000/api/graphql), which allows you to directly run GraphQL queries and mutations.
+
+Congratulations, you're now up and running with Keystone! 🚀
+
+## Try it out in CodeSandbox 🧪
+
+You can play with this example online in a web browser using the free [codesandbox.io](https://codesandbox.io/) service. To launch this example, open the URL <https://githubbox.com/keystonejs/keystone/tree/main/examples/extend-prisma-schema>. You can also fork this sandbox to make your own changes.

examples/extend-prisma-schema/keystone.ts

@@ -0,0 +1,14 @@
+import { config } from '@keystone-6/core';
+import { lists } from './schema';
+
+export default config({
+  db: {
+    provider: 'sqlite',
+    url: process.env.DATABASE_URL || 'file:./keystone-example.db',
+    extendPrismaSchema: schema => {
+      // as an example, we will change the Prisma binary to be linux-musl
+      return schema.replace(/(generator [^}]+)}/g, '$1binaryTargets = ["native", "linux-musl"]\n}');
+    },
+  },
+  lists,
+});

examples/extend-prisma-schema/package.json

@@ -0,0 +1,19 @@
+{
+  "name": "@keystone-6/example-extend-prisma-schema",
+  "version": "0.0.8",
+  "private": true,
+  "license": "MIT",
+  "scripts": {
+    "dev": "keystone dev",
+    "start": "keystone start",
+    "build": "keystone build"
+  },
+  "dependencies": {
+    "@keystone-6/core": "^4.0.0",
+    "@keystone-6/fields-document": "^6.0.0"
+  },
+  "devDependencies": {
+    "typescript": "~4.9.4"
+  },
+  "repository": "https://github.com/keystonejs/keystone/tree/main/examples/extend-prisma-schema"
+}

examples/extend-prisma-schema/sandbox.config.json

@@ -0,0 +1,7 @@
+{
+  "template": "node",
+  "container": {
+    "startScript": "keystone dev",
+    "node": "16"
+  }
+}