env-to-t3

This is a CLI to generate TypeScript code to safely use environment variables with T3 env.

Why?

Direct access to environment variables (e.g. process.env.API_KEY) in your TypeScript code is not safe. If you forget to add the environment variable, your code may break. That's why a tool like T3 Env can be very helpful. You can use your environment variables in a safe and fully typed way thanks to Zod.

But writing the code is a bit tedious. For example, you have 3 environment variables that you want to use in your code. During development, you need to write the .env file like this

DATABASE_URL=postgres://localhost:5432/my-app
OPEN_AI_API_KEY=1234567890
NEXT_PUBLIC_PUBLISHABLE_KEY=1234567890

Then write the code like this:

import { createEnv } from '@t3-oss/env-nextjs'
import { z } from 'zod'

export const env = createEnv({
  server: {
    DATABASE_URL: z.string().url(),
    OPEN_AI_API_KEY: z.string().min(1),
  },
  client: {
    NEXT_PUBLIC_PUBLISHABLE_KEY: z.string().min(1),
  },
  experimental__runtimeEnv: {
    NEXT_PUBLIC_PUBLISHABLE_KEY: process.env.NEXT_PUBLIC_PUBLISHABLE_KEY,
  },
})

Note that you have to write NEXT_PUBLIC_PUBLISHABLE_KEY four times in total.

By using this script, you don't have to write the code by hand anymore. Just run the script and it will generate the code for you.

Features

• By default, all environment variables are considered to be strings.
• If the environment variable ends with _URL, it will be converted to a z.string().url() type.
• If the environment variable has a NEXT_PUBLIC_ prefix, it is considered a client-side environment variable. You can override this prefix by using the --client-prefix flag.
• If the environment variable has a # required comment, it has a .min(1) constraint.
• If the environment variable has a # number comment, it will have a .number() constraint.
• If the environment variable has the # default comment, it will have a .default()constraint. The value of the default will be the value of the environment variable if it exists, or 0 if it is a number, or an empty string if it is a string.

For example, you have the following .env file:

DATABASE_URL=abcd
OPEN_AI_API_KEY=1 # number required
NEXT_PUBLIC_PUBLISHABLE_KEY=abcd
MINIMUM_DAYS=1 # number
MINIMUM_MEMBERS=10 # number default required

Running the env-to-t3 script will produce the following env.ts file:

  server: {
    DATABASE_URL: z.string().optional(),
    OPEN_AI_API_KEY: z.number().min(1),
    MINIMUM_DAYS: z.number().default(1).optional(),
    MINIMUM_MEMBERS: z.number().min(1).default(10),
  },
  client: {
    NEXT_PUBLIC_PUBLISHABLE_KEY: z.string().optional(),
  },
  experimental__runtimeEnv: {
    NEXT_PUBLIC_PUBLISHABLE_KEY: process.env.NEXT_PUBLIC_PUBLISHABLE_KEY,
  }
});

Install

npm i -g env-to-t3

Or you can run the command directly:

npx env-to-t3 -i .env

CLI

  Usage
    $ env-to-t3 [input]

  Options
    --input, -i <type> The path to the environment file.  [Default: .env]
    --output, -o The path to write the output. [Default: env.ts]
    --client-prefix, -cp The prefix for client-side environment variables. [Default: NEXT_PUBLIC_]

  Examples
    $ env-to-t3 --input .env

Notes

• The generated code is compatible with Next.js >= 13.4.4 as mentioned in the T3 env documentation.

Development

Run

npx tsx source/cli.tsx -i "./__tests__/.env"

License

MIT

Contact

Nico Prananta