Union of Enum values or object values

[simonepizzamiglio]

Is there any way to create a union validation of enum values or object values?

I tried the code below but it doesn't work:

import {z} from 'zod';

const Fruits = {
  Apple: "apple",
  Banana: "banana",
} as const;

const FruitEnum = z.nativeEnum(Fruits);

type Fruit = z.infer<typeof FruitEnum>; // "apple" | "banana"

const fruitValuesLiterals = Object.values(Fruits).map(value => z.literal(value)); // z.ZodLiteral<"apple" | "banana">[]

const fruitUnion = z.union(fruitValuesLiterals); // ERROR: Argument of type 'ZodLiteral<"apple" | "banana">[]' is not assignable to parameter of type 'readonly [ZodTypeAny, ZodTypeAny, ...ZodTypeAny[]]'.

TS playground code

[PabloLION]

Same issue here. I'm trying to get keys from an object and my Object.keys(DICT).map(value => z.literal(value)); throws the same error. The as const doesn't help either.

[PabloLION]

A similar issue happened in discriminatedUnion. Seems that TS engine cannot deduce the generic types from an identical array constructed with array in the types: [...]`.

Current workaround: I expanded the loop since it's not so long.

/* 
what i expected:  
const fruitUnion = z.union( Object.values(Fruits).map(value => z.literal(value) );

or even better:
const fruitValuesLiterals = Object.values(Fruits).map(value => z.literal(value)); 
const fruitUnion = z.union(fruitValuesLiterals);
*/

// the work-around: 
const fruitUnion = z.union([z.literal('apple'), z.literal('banana')]);

[devklick]

It compiles OK if you create the union and the litterals in a single line, e.g.

const fruitUnion = z.union([z.literal('apple'), z.literal('banana')]); // type: z.ZodUnion<[z.ZodLiteral<"apple">, z.ZodLiteral<"banana">]>

However as soon as you try and split the creation of the litterals and union into multiple steps, it cant compile:

const fruitValuesLiterals = [z.literal('apple'), z.literal('banana')]; // type: (z.ZodLiteral<"apple"> | z.ZodLiteral<"banana">)[]
const fruitUnion = z.union(fruitValuesLiterals); // Argument of type '(ZodLiteral<"apple"> | ZodLiteral<"banana">)[]' is not assignable to parameter of type 'readonly [ZodTypeAny, ZodTypeAny, ...ZodTypeAny[]]'. Source provides no match for required element at position 0 in target.

Based on this, I'm thinking that it's not currently possible to achieve this. However It would be good to see this in the future.

[devklick]

Just to expand on my previous comment, it does compile if you specify the type as a tuple with ZodLitteral types, e.g:

const fruitValuesLiterals: [z.ZodLiteral<'apple'>, z.ZodLiteral<'banana'>] = [z.literal('apple'), z.literal('banana')]; // type: (z.ZodLiteral<"apple"> | z.ZodLiteral<"banana">)[]
const fruitUnion = z.union(fruitValuesLiterals); // type: z.ZodUnion<[z.ZodLiteral<"apple">, z.ZodLiteral<"banana">]>

However I'm not sure of any way to build this type dynamically based on the values in the enum/const object.

[PabloLION]

@devklick I think you are missing the point here:

What I wanted was to use iteration with zod and something like Template Literal Types.

The point of this issue is to say that it only works with z.union([z.literal('apple'), z.literal('banana')]) but not with z.union(Object.values(Fruits).map(value => z.literal(value))). You are reiterating that in the first case it works and didn't mention the second case at all. (Tho AFAIK it is hard to achieve in TS.)

[devklick]

@PabloLION Thanks for clarifying. Can you elaborate on your workaround? Not sure what you mean by expanding the loop.

[PabloLION]

@devklick Sorry for the vagueness. I edited the post before. It's just like what you did.

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[PabloLION]

Hi @colinhacks , would you mind checking this issue and decide if we are going to work on it? Thanks in advance.

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.