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Schema Types

Schemas are useful but not required, envitron loads all envs from a file and those envs can still be used, only they won't be type safe Envitron supports the following schema types for environment variables:

String​

schema.string();
schema.string({ optional: true });

Number​

schema.number();
schema.number({ optional: true });

Boolean​

schema.boolean();
schema.boolean({ optional: true });

Enum​

schema.enum(['development', 'production', 'test'] as const);

Array​

schema.array();
schema.array({ optional: true });

Custom​

schema.custom((value) => {
  // Your custom validation logic here
  return transformedValue;
});

schema.custom(
  (value) => {
    // Your custom validation logic here
    return transformedValue;
  },
  { optional: true }
);

The custom validator allows you to define your own validation and transformation logic for environment variables. The validator function receives the raw environment value and should return the transformed value. The type of the env will be inferred from the return type of the function.

Example​

const env = createEnvSchema((schema) => ({
  // Divide the environment value by 2
  CUSTOM_NUMBER: schema.custom((value) => Number(value) / 2),

  // Transform a string to uppercase
  CUSTOM_STRING: schema.custom((value) => String(value).toUpperCase()),

  // Optional custom validator
  OPTIONAL_CUSTOM: schema.custom((value) => Number(value) * 2, { optional: true }),
}));

Options​

  • optional: true — makes the variable optional (value may be undefined)

Example​

const env = createEnvSchema((schema) => ({
  HOST: schema.string(),
  PORT: schema.number(),
  DEBUG: schema.boolean({ optional: true }),
  NODE_ENV: schema.enum(['development', 'production', 'test'] as const),
  ALLOWED_HOSTS: schema.array({ optional: true }),
  CUSTOM_VALUE: schema.custom((value) => Number(value) / 2),
}));

See API Reference for usage details.