SQL Code Generation

paradox generate --sqlite [--path PATH]
paradox generate --postgresql [--path PATH]

Paradox generates DDL (Data Definition Language) for SQLite and PostgreSQL.

Product Types → Tables

Input:

type User
  name: Text
  email: Text
  age: Integer

SQLite output:

CREATE TABLE "User" (
  "id" INTEGER PRIMARY KEY AUTOINCREMENT,
  "name" TEXT NOT NULL,
  "email" TEXT NOT NULL,
  "age" INTEGER NOT NULL
);

Every table gets an auto-incrementing id primary key.

Foreign Keys

Product fields that reference other product types become foreign keys:

type Post
  author: User
  title: Text
  content: Text
  published: Boolean
CREATE TABLE "Post" (
  "id" INTEGER PRIMARY KEY AUTOINCREMENT,
  "author" INTEGER NOT NULL,
  "title" TEXT NOT NULL,
  "content" TEXT NOT NULL,
  "published" INTEGER NOT NULL,
  FOREIGN KEY("author") REFERENCES "User"("id")
);

Typed Foreign Keys

Key wrap types generate explicit foreign key references:

wrap Key a: Integer

type Comment
  postId: Key Post
  userId: Key User
  body: Text
CREATE TABLE "Comment" (
  "id" INTEGER PRIMARY KEY AUTOINCREMENT,
  "postId" INTEGER NOT NULL,
  "userId" INTEGER NOT NULL,
  "body" TEXT NOT NULL,
  FOREIGN KEY("postId") REFERENCES "Post"("id"),
  FOREIGN KEY("userId") REFERENCES "User"("id")
);

Validation → CHECK Constraints

Wrap type validations become inline CHECK constraints:

wrap Age: Integer

valid Age
  unwrap >= 0
  unwrap <= 150

type Profile
  user: User
  age: Age
  bio: Text?
CREATE TABLE "Profile" (
  "id" INTEGER PRIMARY KEY AUTOINCREMENT,
  "user" INTEGER NOT NULL,
  "age" INTEGER NOT NULL,
  "bio" TEXT,
  FOREIGN KEY("user") REFERENCES "User"("id"),
  CONSTRAINT "Profile_age_check" CHECK (age >= 0 AND age <= 150)
);

Union Types

Unions become tables with a _tag discriminator column:

CREATE TABLE "PaymentStatus" (
  "id" INTEGER PRIMARY KEY AUTOINCREMENT,
  "_tag" TEXT NOT NULL,
  "pending" INTEGER,
  "completed" INTEGER,
  "failed" TEXT
);

Optional Fields

Optional fields (T?) become nullable columns (no NOT NULL constraint).

Type Mapping

Paradox SQLite PostgreSQL

Integer

INTEGER

BIGINT

Text

TEXT

TEXT

Boolean

INTEGER

BOOLEAN

Double

REAL

DOUBLE PRECISION

See Also