ZOD validation based on another field

Question

Imagine I have an object like

{
  field1: 'test',
  field2: 'test1'
}

How I can create the following validation:

If field1 and field2 both are empty - it is not valid

If field1 and field2 both are not empty - it is not valid

Other cases are valid.

Answer 1

You can use .refine():

const res = z.object({
    field1: z.string().optional(),
    field2: z.string().optional(),
}) 
    .refine(schema => {
        return !(
            schema.field1 === undefined && 
            schema.field2 === undefined ||
            schema.field2 !== undefined && 
            schema.field1 !== undefined
        ); 
    }, "Your message");