refract

Generate Prisma from TypeScript

Installation

npm i -D @cwqt/refract
yarn add -D @cwqt/refract

Usage

See here for a full demo.

• Models
• Scalars
  • @db attributes
• Relationships
  • Examples
    • OneToOne
    • Implicit ManyToMany
    • Ambiguous relations
    • Referentials Actions
• Enums
• Blocks
• Mixins
• Handling circular relationships

Use the Refract default export of this package to generate a Prisma file.

// schema.ts

// Import the entry-point
import Refract from '@cwqt/refract';
// Import your custom Models
import { Roles, User, Posts } from './models';

Refract({
  // Supply models/enums for generation
  schema: [Roles, User, Posts],
  // https://www.prisma.io/docs/reference/api-reference/prisma-schema-reference#datasource
  datasource: {
    provider: 'postgresql',
    url: 'env("DATABASE_URL")',
    shadowDatabaseUrl: 'env("DATABASE_SHADOW_URL")',
    referentialIntegrity: 'prisma',
  },
  // https://www.prisma.io/docs/reference/api-reference/prisma-schema-reference#generator
  generators: [
    {
      provider: 'prisma-client-js',
      previewFeatures: ['referentialIntegrity'],
      engineType: 'library',
      binaryTargets: ['native'],
    },
  ],
  // Define output path for generated Prisma file
  output: path.join(process.cwd(), 'schema.prisma'),
});

A command like npx ts-node schema.ts will run this TypeScript code & generate the resulting Prisma file at the output path.

Models

const User = Model('User', 'This is an optional comment');

User.Field('id', Int(Id, Default('autoincrement()')), 'The primary key');

// // This is an optional comment
// model User {
//    // The primary key
//    id  Int @id @default(autoincrement())
// }

Model uses a fluid interface, so you can chain the following methods:

• .Field(name, scalar): Add a scalar column to a Model
• .Relation(name, relation): Add a relationship to a Model
• .Block(compound): Add a block field, e.g. @@id, @@unique, @@map
• .Mixin(mixin): Inherit columns from a Mixin for compositional Models
• .Raw(value): Escape hatch into writing raw Prisma

Scalars

Scalars are the types of data that the column contains, Int, String etc. You can define & re-use Scalars wherever in your models

const PrimaryKey = Int(Id, Default('autoincrement()'));

// id Int   @id @default("autoincrement()")
m.Field('id', PrimaryKey);

Modifiers

Modifiers are functions/objects that append attributes to a column e.g.

// String? @default("Hello World")
String(Default('Hello World'), Nullable);

// Int @id @unique @default(autoincrement())
Int(Id, Unique, Default('autoincrement()'));

// DateTime @default(now()) @updatedAt
DateTime(Default('now()'), UpdatedAt);

Certain modifiers are constrained to certain scalars, the mapping is:

• String: Unique, Id, Default(string | 'auto()'), Limit(number)
• Int: Unique, Id, Default('cuid' | 'autoincrement()' | 'uuid()' | number)
• Float: Unique, Default(number)
• BigInt: Unique, Default(BigInt)
• Bytes: Unique
• Decimal: Unique
• Boolean: Unique
• DateTime: Default('now()'), UpdatedAt
• Unsupported

Additionally all scalars can use: Nullable, Map, Ignore, Raw & Array modifiers.

The Raw() modifier can be used as an escape hatch:

// String  @db.ObjectId
String(Raw('@db.ObjectId'));

@db attributes

Currently there's support for mysql, postgresql, cockroachdb & mongodb @db attributes, and can be used like all the other modifiers.

import { MySql as db } from '@cwqt/refract';

// email String @db.VarChar(255)
m.Field('email', String(db.VarChar(255)));

Check src/public/db/mysql.ts (mongo.ts/postgresql.ts/cockroach.ts) for list of mappings between scalar types & attributes.

Relationships

• OneToMany (model, name?, ...modifiers)
  • Nullable
• OneToOne (model, name?, fields, references, ...modifiers)
• OneToOne (model, name?, ...modifiers)
  • Nullable, OnUpdate(Action), OnDelete(Action)
• ManyToOne (model, name?, fields, references, ...modifiers)
  • Nullable, OnUpdate(Action), OnDelete(Action)

Where Action is one of: Cascade, Restrict, NoAction, SetNull, SetDefault

Examples

OneToOne

const User = Model('User');
const Something = Model('Something');

Something
  .Field('id', PrimaryKey)
  // Holds foreign key
  .Field('userId', Int())
  .Relation('user', OneToOne(User, Fields('userId'), References('id')));
  // Alternatively you can do Fields('userId', Int()) to avoid the extra
  // .Field() call, this'll add the column to the model for you

User
  .Field('id', PrimaryKey)
  .Relation('thingy', OneToOne(Something));

Implicit ManyToMany

https://www.prisma.io/docs/concepts/components/prisma-schema/relations/many-to-many-relations#implicit-many-to-many-relations

const Post = Model('Post');
const Category = Model('Category');

Post
  .Field('id',            Int(Id, Default('autoincrement()')))
  .Relation('categories', OneToMany(Category));

Category
  .Field('id',            Int(Id, Default('autoincrement()')))
  .Relation('posts',      OneToMany(Post));

Ambiguous relations

The 2nd parameter of the Relation can be a string & explicitly denote the name of the relation.

// pinnedBy   User?   @relation(name: "PinnedPost", fields: [pinnedById], references: [id])
m.Relation(
  'pinnedBy',
  OneToOne(
    User,
    'PinnedPost',
    Fields('pinnedById'),
    References('id'),
    Nullable,
  ),
);

Referentials Actions

OnUpdate & OnDelete modifiers can be used as follows:

// tag    Tag?  @relation(fields: [tagId], references: [id], onUpdate: Cascade, onDelete: Cascade)
m.Relation(
  'tag',
  ManyToOne(
    Fields('tagId'),
    References('id'),
    OnUpdate('Cascade'),
    OnDelete('Cascade'),
    Nullable,
  ),
);

Enums

Composed of two parts:

• Enum(name, comment?, ...Key)
• Key(value, ...modifiers, comment?)
  • Map

const Animal = Enum(
  'Animal',
  Key('Seacow'),
  Key('Capybara'),
  Key('Otter', Map('otter')),
);

// fave  Animal @default(Seacow)
// null  Animal?
model
  .Field('fave', Animal('Seacow'))
  .Field('null', Animal());

const WithComment = Enum(
  "Foo", "This is with a comment",
  Key("Bar", "Another comment")
);
// // This is with a comment
// enum Foo {
//  // Another comment
//  Bar
// }

Blocks

Used for adding fields like @@map, @@id, @@fulltext etc.

import { Compound, Mongo as db } from '@cwqt/refract';

// Creating a compound index
model
  .Field('id', Int(Id, Default('autoincrement()')))
  .Field('authorId', Int())
  .Relation('author', ManyToOne(User, Fields('authorId'), References('id')))
  .Block(Compound.Id('id', 'authorId'));

// e.g. in MongoDB schemas
Model('User')
  .Field('id', String(Id, db.ObjectId, Map('_id')))
  .Block(Compound.Map('users'));

Mixins

Allows you to re-use groups of fields, compositional models.

const Timestamps = Mixin()
  .Field('createdAt', DateTime(Default('now()')))
  .Field('updatedAt', DateTime(Nullable, UpdatedAt));

const User = Model('User').Field('id', PrimaryKey).Mixin(Timestamps);

// User will now have `createdAt` & `updatedAt` columns

Programmatic usage

const prisma = Refract.generate({
  datasource: {...},
  generators: [...],
  schema
})

console.log(prisma); // schema.prisma contents

Handling circular relationships

At some point you'll want to split the schema across files, which introduces issues with circular relationships when you're importing for .Relation()s in Node

One way to get around this is to have a file with all the models/enums defined, and have files import those & apply the fields, e.g.

// models.ts ------------------------------
const User = Model("User");
const Post = Model("Posts");
// ... and all the other Models

// users.ts ------------------------------
import { User, Post } from './models'

User
  .Field("id",        Int(Id, Default("autoincrement()")))
  .Relation("posts",  OneToMany(Post))

// posts.ts  ------------------------------
import { User, Post } from './models'

Post
  .Field("id",        Int(Id, Default("autoincrement()")))
  .Field("authorId",  Int())
  .Relation("author", ManyToOne(User, Fields("authorId"), References("id")))

// refract.ts ------------------------------
import * as schema from './models'

// IMPORTANT: import the model files which performs the `.Field()`, `.Relation()`
// etc. calls, thereby adding the columns to the models
import "./posts";
import "./users";

Refract({
  datasource: {...},
  generators: [...],
  schema
})