I have the following code, which gives me ts(1337) error:
type Options = 'option1' | 'option2' | 'option3'
type ComplexValue = { [key: Options]: string } // ts error 1337
what I want to achieve here is that keys of ComplexValue objects can be only one of Options.
if I try to fix and define it differently by one of the below options:
type ComplexValue = { [K in Options]: string }
// or simply
type ComplexValue = Record<ServerFilterOperator, string>
and then trying to write something like this
const something: ComplexValue = { option1: 'ziv' }
then I get the below error
Type '{ [x: string]: string; }' is missing the following properties from type 'ComplexValue': option2, option3.ts(2740)
A workaround I can apply is adding ? to the definition type ComplexValue = { [key in Options]?: string } - this will apply that all keys are optional. But I actually wants to validate only single key:value are passed.
What is the proper way validate that keys of ComplexValue objects can be only one of Options and only one key:value pair is on the object?
It's a little tricky but you can get it done. Inspired by a few other answer I came up with this:
type RequireSingle<K extends PropertyKey> = {
[P in K]: {[V in P]: string} & Partial<
Record<Exclude<K, P>, never>
> extends infer T
? {[X in keyof T]: T[X]}
: never;
}[K];
type ComplexValue = RequireSingle<Options>;
const complex: ComplexValue = {};
// . ~~~~~~~~ Type '{}' is not assignable to type 'ComplexValue'.
const complex1: ComplexValue = {
option1: ""
};
const complex2: ComplexValue = {
// ~~~~~~~~ Type '{ option1: string; option2: string; }' is not assignable
// to type 'ComplexValue'.
option1: "",
option2: ""
};