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ts-to-zod

Generate Zod schemas (v3) from Typescript types/interfaces.

Version Github CI codecov License oclif

Usage

$ yarn add --dev ts-to-zod
$ yarn ts-to-zod src/iDontTrustThisApi.ts src/nowIcanValidateEverything.ts

That's it, go to src/nowIcanValidateEverything.ts file, you should have all the exported interface and type as Zod schemas with the following name pattern: ${originalType}Schema.

Embedded validation

To make sure the generated zod schemas are 100% compatible with your original types, this tool is internally comparing z.infer<generatedSchema> and your original type. If you are running on those validation, please open an issue 😀

Notes:

  • Only exported types/interface are tested (so you can have some private types/interface and just exports the composed type)
  • Even if this is not recommended, you can skip this validation step with --skipValidation. (At your own risk!)

JSDoc Tag Validators

This tool supports some JSDoc tags (inspired by OpenAPI) to generate additional Zod schema validators.

List of supported keywords:

JSDoc keyword JSDoc Example Generated Zod validator
@minimum {number} [err_msg] @minimum 42 z.number().min(42)
@maximum {number} [err_msg] @maximum 42 Must be < 42 z.number().max(42, "Must be < 42")
@minLength {number} [err_msg] @minLength 42 z.string().min(42)
@maxLength {number} [err_msg] @maxLength 42 z.string().max(42)
@format {FormatType} [err_msg] @format email z.string().email()
@pattern {regex}

Note: Due to parsing ambiguities, @pattern does not support generating error messages.		 @pattern ^hello z.string().regex(/^hello/)

By default, FormatType is defined as the following type (corresponding Zod validator in comment):

type FormatType =
  | "date-time" // z.string().datetime()
  | "date" // z.string().date()
  | "time" // z.string().time()
  | "duration" // z.string().duration()
  | "email" // z.string().email()
  | "ip" // z.string().ip()
  | "ipv4" // z.string().ip()
  | "ipv6" // z.string().ip()
  | "url" // z.string().url()
  | "uuid"; // z.string().uuid()

However, see the section on Custom JSDoc Format Types to learn more about defining other types of formats for string validation.

Those validators can be combined:

// source.ts
export interface HeroContact {
  /**
   * The email of the hero.
   *
   * @format email
   */
  email: string;

  /**
   * The name of the hero.
   *
   * @minLength 2
   * @maxLength 50
   */
  name: string;

  /**
   * The phone number of the hero.
   *
   * @pattern ^([+]?d{1,2}[-s]?|)d{3}[-s]?d{3}[-s]?d{4}$
   */
  phoneNumber: string;

  /**
   * Does the hero has super power?
   *
   * @default true
   */
  hasSuperPower?: boolean;

  /**
   * The age of the hero
   *
   * @minimum 0
   * @maximum 500
   */
  age: number;
}

// output.ts
export const heroContactSchema = z.object({
  /**
   * The email of the hero.
   *
   * @format email
   */
  email: z.string().email(),

  /**
   * The name of the hero.
   *
   * @minLength 2
   * @maxLength 50
   */
  name: z.string().min(2).max(50),

  /**
   * The phone number of the hero.
   *
   * @pattern ^([+]?d{1,2}[-s]?|)d{3}[-s]?d{3}[-s]?d{4}$
   */
  phoneNumber: z.string().regex(/^([+]?d{1,2}[-s]?|)d{3}[-s]?d{3}[-s]?d{4}$/),

  /**
   * Does the hero has super power?
   *
   * @default true
   */
  hasSuperPower: z.boolean().default(true),

  /**
   * The age of the hero
   *
   * @minimum 0
   * @maximum 500
   */
  age: z.number().min(0).max(500),
});

Other JSDoc tags

Other JSDoc tags are available:

JSDoc keyword JSDoc Example Description Generated Zod
@description {value} @description Full name Sets the description of the property z.string().describe("Full name")
@default {value} @default 42 Sets a default value for the property z.number().default(42)
@strict @strict Adds the strict() modifier to an object z.object().strict()
@schema @schema .catch('foo') If value starts with a ., appends the specified value to the generated schema. Otherwise this value will override the generated schema. z.string().catch('foo')

JSDoc tag for union types

JSDoc keyword JSDoc Example Description Generated Zod
@discriminator {propName} @discriminator id Generates a z.discriminatedUnion() instead of union z.discriminatedUnion("id", ...)

Example:

// source.ts
/**
 * @discriminator type
 **/
export type Person =
  | { type: "Adult"; name: string }
  | { type: "Child"; age: number };

// output.ts
// Generated by ts-to-zod
import { z } from "zod";

export const personSchema = z.discriminatedUnion("type", [
  z.object({
    type: z.literal("Adult"),
    name: z.string(),
  }),
  z.object({
    type: z.literal("Child"),
    age: z.number(),
  }),
]);

JSDoc tags for elements of string and number arrays

Elements of string and number arrays can be validated using the following JSDoc tags (for details see above).

JSDoc keyword
@elementDescription {value}
@elementMinimum {number} [err_msg]
@elementMaximum {number} [err_msg]
@elementMinLength {number} [err_msg]
@elementMaxLength {number} [err_msg]
@elementFormat {FormatType} [err_msg]
@elementPattern {regex}

Example:

// source.ts
export interface EnemyContact {
  /**
   * The names of the enemy.
   *
   * @elementMinLength 5
   * @elementMaxLength 10
   * @minLength 2
   * @maxLength 50
   */
  names: string[];

  /**
   * The phone numbers of the enemy.
   *
   * @description Include home and work numbers
   * @elementPattern ^([+]?d{1,2}[-s]?|)d{3}[-s]?d{3}[-s]?d{4}$
   */
  phoneNumbers: string[];
}

// output.ts
export const enemyContactSchema = z.object({
  /**
   * The names of the enemy.
   *
   * @elementMinLength 5
   * @elementMaxLength 10
   * @minLength 2
   * @maxLength 50
   */
  name: z.array(z.string().min(5).max(10)).min(2).max(50),

  /**
   * The phone numbers of the enemy.
   *
   * @elementPattern ^([+]?d{1,2}[-s]?|)d{3}[-s]?d{3}[-s]?d{4}$
   */
  phoneNumbers: z
    .array(z.string().regex(/^([+]?d{1,2}[-s]?|)d{3}[-s]?d{3}[-s]?d{4}$/))
    .describe("Include home and work numbers"),
});

Advanced configuration

If you want to customize the schema name or restrict the exported schemas, you can do this by adding a ts-to-zod.config.js at the root of your project.

Just run yarn ts-to-zod --init and you will have a ready to use configuration file (with a bit of type safety).

You have two ways to restrict the scope of ts-to-zod:

  • nameFilter will filter by interface/type name
  • jsDocTagFilter will filter on jsDocTag

Example:

// ts-to-zod.config.js
/**
 * ts-to-zod configuration.
 *
 * @type {import("./src/config").TsToZodConfig}
 */
module.exports = [
  {
    name: "example",
    input: "example/heros.ts",
    output: "example/heros.zod.ts",
    jsDocTagFilter: (tags) => tags.map((tag) => tag.name).includes("toExtract"), // <= rule here
  },
];

// example/heros.ts
/**
 * Will not be part of `example/heros.zod.ts`
 */
export interface Enemy {
  name: string;
  powers: string[];
  inPrison: boolean;
}

/**
 * Will be part of `example/heros.zod.ts`
 * @toExtract
 */
export interface Superman {
  name: "superman" | "clark kent" | "kal-l";
  enemies: Record<string, Enemy>;
  age: number;
  underKryptonite?: boolean;
}

Please note: if your exported interface/type have a reference to a non-exported interface/type, ts-to-zod will not be able to generate anything (missing dependencies will be reported).

Custom JSDoc Format Types

ts-to-zod already supports converting several @format types such as email and ip to built-in Zod string validation functions. However, the types supported out of the box are only a subset of those recognized by the OpenAPI specification, which doesn't fit every use case. Thus, you can use the config file to define additional format types using the customJSDocFormatTypes property like so:

{
  "customJSDocFormatTypes": {
    [formatTypeNoSpaces]:
      | string
      | {regex: string, errorMessage: string}
  }
}

Here is an example configuration:

{
  "customJSDocFormatTypes": {
    "phone-number": "^\\d{3}-\\d{3}-\\d{4}$",
    "date": {
      "regex": "^\\d{4}-\\d{2}-\\d{2}$",
      "errorMessage": "Must be in YYYY-MM-DD format."
    }
  }
}

As a result, ts-to-zod will perform the following transformation:

TypeScript Zod 
interface Info {
  /**
   * @format date
   */
  birthdate: string;
  /**
   * @format phone-number Must be a valid phone number.
   */
  phoneNumber: string;
}
 
const infoSchema = z.object({
  /**
   * @format date
   */
  birthdate: z
    .string()
    .regex(/^\d{4}-\d{2}-\d{2}$/, "Must be in YYYY-MM-DD format."),
  /**
   * @format phone-number
   */
  phoneNumber: z
    .string()
    .regex(/^\d{3}-\d{3}-\d{4}$/, "Must be a valid phone number."),
});

Limitation

Since we are generating Zod schemas, we are limited by what Zod actually supports:

  • No type generics
  • No Record<number, …>
  • …

To resume, you can use all the primitive types and some the following typescript helpers:

  • Record<string, …>
  • Pick<>
  • Omit<>
  • Partial<>
  • Required<>
  • Array<>
  • Promise<>

Type references

This utility is designed to work with one file at a time (it will not split one file into several), and will handle references to types from the same file:

// source.ts
export type Id = string;
export interface Hero {
  id: Id;
  name: string;
}

// output.ts
export const idSchema = z.string();
export const heroSchema = z.object({
  id: idSchema,
  name: z.string(),
});

Non-Zod imports

ts-to-zod can reference imported types from other modules but will use an any validation as placeholder, as we cannot know their schema.

// source.ts
import { Person } from "@3rdparty/person";
import { Villain } from "./villain";

export interface Hero {
  name: string;
  realPerson: Person;
  nemesis: Villain;
}

// output.ts

const personSchema = z.any();

const villainSchema = z.any();

export const heroSchema = z.object({
  name: z.string(),
  realPerson: personSchema,
  nemesis: villainSchema;
});

Zod Imports

If an imported type is referenced in the ts-to-zod.config.js config (as input), this utility will automatically replace the import with the given output from the file, resolving the relative paths between both.

//ts-to-zod.config.js
/**
 * ts-to-zod configuration.
 *
 * @type {import("./src/config").TsToZodConfig}
 */
module.exports = [
  {
    name: "villain",
    input: "src/villain.ts",
    output: "src/generated/villain.zod.ts",
    getSchemaName: (id) => `z${id}`
  },
   {
    name: "hero",
    input: "src/example/heros.ts",
    output: "src/example/heros.zod.ts",
  },
];

// heros.ts (input)
import { Person } from "@3rdparty/person";
import { Villain } from "../villain";

export interface Hero {
  name: string;
  realPerson: Person;
  nemesis: Villain;
}

// heros.zod.ts (output)
import { zVillain } from "../generated/villain.zod";

const personSchema = z.any();

export const heroSchema = z.object({
  name: z.string(),
  realPerson: personSchema,
  nemesis: zVillain;
});

Programmatic API

You need more than one file? Want even more power? No problem, just use the tool as a library.

High-level function:

  • generate take a sourceText and generate two file getters

Please have a look to src/core/generate.test.ts for more examples.

Low-level functions:

  • generateZodSchema help you to generate export const ${varName} = ${zodImportValue}.object(…)
  • generateZodInferredType help you to generate export type ${aliasName} = ${zodImportValue}.infer<typeof ${zodConstName}>
  • generateIntegrationTests help you to generate a file comparing the original types & zod types

To learn more about those functions or their usages, src/core/generate.ts is a good starting point.

Local development

$ git clone
$ cd ts-to-zod
$ yarn
$ yarn build
$ ./bin/run
USAGE
  $ ts-to-zod [input] [output]
  ...

You also have plenty of unit tests to play safely:

$ yarn test --watch

And a playground inside example, buildable with the following command:

$ yarn gen:example

Last note, if you are updating src/config.ts, you need to run yarn gen:config to have generate the schemas of the config (src/config.zod.ts) (Yes, we are using the tool to build itself #inception)

Have fun!