@elhanmah/prisma-to-zod NPM

Reasoning for the Fork

There are other libraries out there made to generate Zod schemas from Prisma models, but the reason I like this more than some alternatives is because of its simplicity and ease of use. I plan to keep this library that way and will be skeptical of adding any features that might significantly increase the complexity of the library.

The original zod-prisma library is no longer maintained. When I tried to use it, I ran into a bug that made the library unusable. More on that here.

I tried contacting the original author, but he was unresponsive, so there was no way for me to get the bug fixed. I decided to fork the project, fix the bug, publish it as a new library, and maintain it myself. I also plan to add some new features that I think would be useful.

First of all, I added better ESLint, Prettier, and TypeScript configurations/checks to the project. I also plan to bump up all of the dependencies to their latest versions so that the library is up to date, and consider switching some of the dependencies to more modern alternatives.

I also plan on keeping this library compatible with the latest versions of Prisma (currently v5.19.1) and Zod (currently v3.23.8).

About The Project

I got tired of having to manually create Zod schemas for my Prisma models and of updating them everytime I made schema changes. This provides a way to automatically generate them from your Prisma schema.

Built With

Getting Started

To get a local copy up and running follow these simple steps.

Prerequisites

This project utilizes yarn and if you plan on contributing, you should use it as well.

npm install -g yarn

Installation

Ensure your tsconfig.json enables the compiler's strict mode. Zod requires it and so do we, you will experience TS errors without strict mode enabled
Add @elhanmah/prisma-to-zod as a dev dependency
```
yarn add -D @elhanmah/prisma-to-zod
```

Add the prisma-to-zod generator to your schema.prisma

generator zod {
  provider                 = "prisma-to-zod"
  output                   = "./zod" // (default) the directory where generated zod schemas will be saved

  relationModel            = true // (default) Create and export both plain and related models.
  // relationModel         = "default" // Do not export model without relations.
  // relationModel         = false // Do not generate related model

  modelCase                = "PascalCase" // (default) Output models using pascal case (ex. UserModel, PostModel)
  // modelCase             = "camelCase" // Output models using camel case (ex. userModel, postModel)

  modelSuffix              = "Model" // (default) Suffix to apply to your prisma models when naming Zod schemas

  imports                  = null // (default) will import the referenced file in generated schemas to be used via imports.someExportedVariable

  // https://www.prisma.io/docs/concepts/components/prisma-client/working-with-fields/working-with-json-fields#filtering-by-null-values
  prismaJsonNullability    = true // (default) uses prisma's scheme for JSON field nullability
  // prismaJsonNullability = false // allows null assignment to optional JSON fields

  prisma                   = "@prisma/client" // Path to prisma client, defaults to '@prisma/client'

  optionalRelations        = true // (default) all relations generated on the relation schema will be optional
}

Run npx prisma generate or yarn prisma generate to generate your zod schemas
Import the generated schemas from your selected output location

Usage

JSDoc Generation

Rich-comments in the Prisma schema will be transformed into JSDoc for the associated fields:

Note: make sure to use a triple-slash. Double-slash comments won't be processed.

model Post {
  /// The unique identifier for the post
  /// @default {Generated by database}
  id String @id @default(uuid())

  /// A brief title that describes the contents of the post
  title String

  /// The actual contents of the post.
  contents String
}

Generated code:

export const PostModel = z.object({
  /**
   * The unique identifier for the post
   * @default {Generated by database}
   */
  id: z.string().uuid(),
  /**
   * A brief title that describes the contents of the post
   */
  title: z.string(),
  /**
   * The actual contents of the post.
   */
  contents: z.string(),
})

Extending Zod Fields

You can also use the @zod keyword in rich-comments in the Prisma schema to extend your Zod schema fields:

model Post {
  id String @id @default(uuid()) /// @zod.uuid()

  /// @zod.max(255, { message: "The title must be shorter than 256 characters" })
  title String

  contents String /// @zod.max(10240)
}

Generated code:

export const PostModel = z.object({
  id: z.string().uuid(),
  title: z.string().max(255, { message: 'The title must be shorter than 256 characters' }),
  contents: z.string().max(10240),
})

Importing Helpers

Sometimes it is useful to define a custom Zod preprocessor or transformer for your data. @elhanmah/prisma-to-zod enables you to reuse these by importing them via a config options. For example:

generator zod {
  provider      = "prisma-to-zod"
  output        = "./zod"
  imports 		  = "../src/zod-schemas"
}

model User {
  username	String /// @zod.refine(imports.isValidUsername)
}

The referenced file can then be used by simply referring to exported members via imports.whateverExport. The generated zod schema files will now include a namespaced import like the following.

import * as imports from '../../src/zod-schemas'

Custom Zod Schema

In conjunction with this import option, you may want to utilize an entirely custom zod schema for a field. This can be accomplished by using the special comment directive @zod.custom(). By specifying the custom schema within the parentheses you can replace the autogenerated type that would normally be assigned to the field.

For instance if you wanted to use z.preprocess

JSON Fields

JSON fields in Prisma disallow null values. This is to disambiguate between setting a field's value to NULL in the database and having a value of null stored in the JSON. In accordance with this @elhanmah/prisma-to-zod will default to disallowing null values, even if your JSON field is optional.

If you would like to revert this behavior and allow null assignment to JSON fields, you can set prismaJsonNullability to false in the generator options.

Examples

For examples, please refer to the Examples Directory or the Functional Tests

Roadmap

See the open issues for a list of proposed features (and known issues).

Contributing

Contributions are what make the open source community such an amazing place to be learn, inspire, and create. Any contributions you make are greatly appreciated.