Do TypeBox support String Boolean type or Boolean Type Coercion?

[deanrih]

So I'm currently playing around with Zod and TypeBox for loading and parsing an env into a variable that can be used later (e.g. env.ENV_NAME), and I kinda like TypeBox more but there's some thing I'm still figuring out which is getting Boolean from a String or a type coercion, so in Zod, I can do something like

const schema = z.object({
  DEBUG: z.boolean({ coerce: true }),
});

and when given an env file of

DEBUG="true"

the resulting of env.DEBUG is boolean and not a string

meanwhile doing it in TypeBox

const schema = Type.Object({
  DEBUG: Type.Boolean({ ... }),
});

there's no option to allow such behaviour, and using Type.String doesn't seem solve the problem since I need it to be boolean, furthermore I have additional behaviour to parsing logic for TypeBox, which roughly

• Get the env to a variable (something like const currentEnv = process.env;)
• Clean the env to remove any excess (Value.Clean())
• Set the default env for those who have default option set (Value.Default())
• Then check the env against the schema (Value.Check())
• Before finally returned the decoded result (Value.Decode())

Which is working fine when I have all env in string, but now I add Type.Boolean it fails the Value.Check() since the DEBUG="true" recognized as a string instead of boolean or not being coerced into boolean

Is it possible to do it in TypeBox or is it the limitation/out of the scope of this project?

[sinclairzx81]

@deanrih Hi,

The Value.Convert() function will coerce a string "true" into a boolean true. TypeBox treats this as an explicit call you need to make rather than via configuration on the type. The following loosely achieves this.

const Environment = Type.Object({
  DEBUG: Type.Boolean()
})

const R = Value.Convert(Environment, process.env) // will convert "true" to true if possible.

However it's recommended you use Value.Parse for environment loading. TypeBox exposes quite a few low level Value operations for flexibility, but the Parse function internally implements all these operations in a standard way to process a value how you would expect.

const Environment = Type.Object({
  DEBUG: Type.Boolean({ default: false }) // default values supported with Parse
})

const R = Value.Parse(Environment, process.env) // will convert "true" to true if possible.

I would have a go using Parse first. If you need custom environment variable processing, take a look at the TypeBox Parse implementation. This library encourages users to mix and match various components of the library to construct various pipelines for validation, the Parse function is a good place to start if you need that level of functionality.

https://github.com/sinclairzx81/typebox#values-parse

https://github.com/sinclairzx81/typebox/blob/master/src/value/parse/parse.ts#L44-L68

Hope this helps
S

[deanrih]

Ah, thank you, yeah I was expecting something with options and not explicit function call, but I tried and adding the Value.Convert just after Value.Default but before the Value.Check and it work

Thank you