How to create typebox type that is the same as typescript typeof MyEnum?

[meightythree]

I have the following enum:

enum MyEnum {
   first = 'first',
   second = 'second',
}

How to create a typebox type which represents the enum content?
In typescript it is done by typeof MyEnum

[sinclairzx81]

@meightythree Hi,

You can pass a enum into Type.Enum which will create a union (anyOf) schema. You can then use Static<typeof T> which will return the original enum type (as it would be understood by TypeScript)

enum MyEnum {
   first = 'first',
   second = 'second',
}

const T = Type.Enum(MyEnum)    // const T = {
                               //   anyOf: [{
                               //       type: 'string',
                               //       const: 'first',
                               //   }, {
                               //       type: 'string',
                               //       const: 'second',
                               //     }
                               //   ],
                               // }

type T = Static<typeof T>      // type T = MyEnum 

function test(value: T) {}   

test(MyEnum.first)           // ok - matches anyOf variant
test(MyEnum.second)          // ok - matches anyOf variant
test(MyEnum)                 // fail - not a anyOf variant

In the above, take note of the third test case. Note that because TypeBox encodes enum as union (in which it only encodes the enum variants), information about the original MyEnum keys are lost (as these may be different). Because of this, there is no way to reproduce the original typeof MyEnum in full, so this is generally unsupported.

Hope this helps
S

[meightythree]

Thank you for the detailed answer!